Linerless pressure-sensitive labels enable the release liner to be eliminated. Either a release coating is applied to the label facestock itself, which prevents the adhesive on the underside from sticking to the label below, or the original clear filmic liner is transferred over the printed face stock to both protect the print and reposition the silicone release coating to the outside of the printed face. The original waste liner is now part of the applied label, so eliminating waste collection and disposal at the end user.
Eliminating or using the release liner in a more sustainable format means that savings can be made in face material costs, since a degree of stiffness is no longer required to peel from a liner. In addition, the number of labels on a roll increases dramatically - which means fewer roll changes - no matrix waste needs to be disposed of as there is no peel gap between labels, and there is a significant reduction in waste.
There are obviously distinct advantages to going linerless. Linerless labels contribute to environmental sustainability, increase production capacity, reduce applicator downtime, decrease inventory space and enable the label user to cut out the stages of liner waste collection and disposal. That can be quite substantial for them.
Linerless pressure-sensitive labels are not new of course. They first came to the fore in the early 1980s, when Waddingtons in the United Kingdom developed a technology and coating system called Monoweb to produce linerless labels which found application in companies like Heinz. They were used with a specially designed applicator system that die-cut and applied the label in one pass.
Today, linerless labels are most commonly found in the form of pressure-sensitive labels for the blank label industry, as well thermal labels used in print and apply weigh-price label dispensers and applicators. They are also popular in market sectors such as food and logistics, but have been slower to make a significant impact in the wider label markets.
That situation is now beginning to change as more countries start to tax liner waste as packaging material rather than industrial process waste, and it is becoming more complicated to dispose of.
A number of companies offer proprietary linerless technology and applicator systems for both primary and secondary product decoration.
These companies include Catchpoint, Ravenwood Packaging, ETI Converting, ILTI and Ritrama CORE, which will all be discussed later.
MANUFACTURE OF LINERLESS PRESSURE-SENSITIVE LABELS
There are two conversion methods used today for linerless labels, and these are described below:
The silicone coating method. The manufacture of linerless labels starts with a converter either printing the desired images on to the face of a web of paper or film material, or by coating a direct thermal material. When printed by the converter this is undertaken in the normal way on a label press by flexography, litho or any other process, and no special printing equipment or technology is required.
A silicone face coating is then applied to the face of the pre-printed web of labels and then a pressure-sensitive adhesive is coated on the reverse of the web, with the label web re-wound on itself. The silicone face coating prevents the adhesive sticking to the facestock when it is wound up. The linerless labels resemble a large roll of printed sticky tape. This can be seen in Figure 7.1.
Figure 7.1 - Linerless labels can be regarded rather like a large roll of adhesive tape
With these types of linerless labels the shape of the label is limited because there is no liner to hold the label in place when it is dispensed and cut with a built-in cutter. In this case linerless label users are limited to square or rectangular shapes – frequently perceived as one of the drawbacks of the technology.
Depending on the proprietary linerless applicator technology being used, the label web may incorporate micro-perforations enabling the label to be separated at a tooling station in the applicator.
Linerless from a laminate. This new development is focussed on the use of filmic materials for product decoration, the most rapidly growing part of the pressure-sensitive label market. Again, an original laminate is printed conventionally, but now after printing, the clear film liner is transferred from the adhesive side to be over-laminated over the printed face. This positions the original release coating to now provide the coating in the linerless format. The major advantage is that this new combination of films allows much reduced face film callipers, particularly as linerless labels do not required the same stiffness characteristics – the peel plate or beak are replaced with cutting or alternative label separation systems.
Some linerless systems allow limited design shapes to the top or bottom of the printed labels. And by printing on an ultra-clear material it is possible to reproduce virtually any shape or size of label possible with conventional pressure-sensitive labels.
One of the distinct advantages of linerless labels is that the release coating is applied to the face of the label. This means that, in addition to preventing the adhesive from sticking to the face beneath it, the release coating also acts as a protective coating for UV, moisture, and chemical resistance, all adding to a label's longevity, as well as protecting the printed image and improving durability in demanding applications.
One of the common misconceptions among label converters is that special printing and converting equipment is needed to print linerless labels.
This is not the case: the labels are made using conventional printing and converting processes. However, it's the point when they are applied (or re-wound prior to application in some cases) where additional or adapted equipment comes into play.
LINERLESS LABEL APPLICATION
Linerless technology ticks many sustainability boxes. It has been used with linerless print and apply label applicators for some years and is now commonly viewed as a 'greener' alternative to conventional self-adhesive print and apply label applicators, eradicating waste, reducing storage space, offering more labels on the roll, and increasing productivity.
Linerless print and apply label applicators normally include a thermal transfer printer to print data onto the linerless material, a cutter to cut the material after it has been printed and an application head of some form to apply the printed label to a product. New systems using lasers may reduce total applied costs.
Moving beyond the widely-used linerless print and apply equipment, improved coating technology, new variations of linerless production and application, and continuously developing linerless applicator equipment all look set to have a big long-term impact in key prime label sectors over the next few years, particularly in food packaging and the health and personal care markets – especially as linerless labels become less and less restrained by size and shape.
Some multinational end users and retailers are starting to push the technology forward in the US and Asia, while in Europe a number of retailers are switching the presentation of some fresh produce trays, ready meals, meat and fish packs, into linerless adhesive sleeve formats, usually with variable weight and price data, where they are beginning to replace both conventional pressure-sensitive labels and carton board sleeves.
Linerless is also poised to make further inroads into the beverage sector with the labeling of glass bottles and jars, while continuing to build on existing thermal transfer print-and-apply growth in the logistics, and data labeling sectors. Combined with the expansion of used liner recycling schemes, the latest linerless prime and decorative label technologies will undoubtedly make a big contribution towards helping self-adhesive labeling become cleaner and greener in the coming years.
We now turn to an examination of linerless technology by manufacturer.
Figure 7.2 - A two-headed label applicator applying conventional labels on the left and Catchpoint linerless labels on the right
Working closely with established material suppliers, printers and labeling machine manufacturers, Catchpoint was one of the first companies to develop a really practical linerless application system with none of the efficiency and safety risks seen with the earlier label cutting alternatives.
In operation, all Catchpoint related linerless application systems use unique micro-perforation technology.
System benefits include:
A comprehensive range of application options across the whole speed range, including ILTI proprietary rotary units, with an emphasis on the growing film label market offering thinner face materials to lower costs
A simple applicator change kit which can be merged into existing lines to minimize investment costs
A basic label application system that uses micro-perforations accurately imposed by conventional die-cutting systems
A range of shapes which meets many existing label profiles and encourages printed shapes in clear films
An easy switch for elaborately shaped labels to exploit the availability of 'LeanLiners' in the same applicator change kit. Application of 12 micron PET liners is proven
This dual function encourages change with a practical materials approval process and recognition that linerless label supply capacity will require time to develop
Eliminate web break risks still associated with conventional glassine liners
Catchpoint will shortly add an end of line 'Traded Unit' label printing and application system exploiting the efficiency and reliability of laser technology.
Investing in Catchpoint 'LinerLess or LeanLiners' is claimed to offer label users 2-3 percent line efficiency gains with a unique degree of flexibility.
ETI CONVERTING EQUIPMENT
ETI Converting Equipment, the developer of Cohesio equipment, has been working for some years to find solutions to the issue of release liner waste. Their Cohesio press can manufacture pressure-sensitive linerless labels right through from the raw material to the finished label product.
The technology offers converters the ability to siliconize, print, adhesive coat, print again and die-cut at speeds up to 500 ft/minute.
More recently, ETI introduced a linerless labeler which can be retrofitted to existing applicator systems and can be used to transform the linerless 'tape' web into the same range of shapes and sizes allowed by conventional pressure-sensitive label technology.
Figure 7.3 - ETI linerless labeling solution
Being servo-driven it can adjust itself to create each label shape and size.
Ravenwood Packaging is a company that manufactures and sells linerless labeling machinery to label printers as well as to retailers and packers.
The vast majority of Ravenwood linerless labels produced are being used in the fresh food markets. Examples can be found in the packaging for chilled meat, fish and poultry (see Figure 7.4.), as well as plastic and glass bottles and jars.
Ravenwood's technology pairs a Comac 500 coater with a variety of the company’s Nobac applicators. Both machines work together to provide a completely linerless labeling workflow.
The Comac 500 machine is used instead of a slitter rewinder, coating the labels with silicone release on the front of the labelstock and with an adhesive on the back at up to 450 feet/minute. It is specifically designed to work with the Nobac applicator.
The Nobac line of linerless label applicators is available in three different models, the 500, 400v, and 125. The Nobac 500 is an in-line machine developed for retailers and packers and is the most versatile in terms of what types of constructions it can produce.
It is capable of applying sleeves in five formats: top, top and side, top and two sides, C-wrap, and full wrap. In addition to sleeving fixed weight products, it also has the option of linking the machine to weigh scales for variable weight products.
Figure 7.5 - Nobac 500 linerless label applicator_1
Figure 7.5 - Nobac 500 linerless label applicator_2
The Nobac 400v sleever is an applicator focused entirely on C-wrap applications and is capable of labeling irregular packages such as whole birds.
It maintains close control of both ends of the label in the feed system, improving positional accuracy of the label around the package. The feed system is independent of label length and conveyor speed, allowing longer labels to be run without loss of throughput.
Thermal transfer printers can be optionally fitted. These print at the point of application, minimizing wasteful printed labels on changeovers. The machine can also be interfaced with a weighing machine to print variable data if required.
In 2013 Ritrama launched Core Linerless Solutions (CLS) with the aim of revolutionizing the use of linerless technology. The system was developed by Ritrama in collaboration with labeling equipment supplier ILTI and is targeted at high volume global end users in the home, personal care and beverage industries. Ritrama regards CLS as an evolution of pressure sensitive technology rather than a replacement.
Indeed, the supply chain for the Core system is exactly the same as conventional pressure-sensitive labels in terms of efficient wide web silicone and adhesive coating and laminating of liners and face films by Ritrama.
Label converters simply print a laminate, without die-cutting, at full press speed, and this is converted on the specially designed RG20 converting machine module (Figure 7.7), which encapsulates the print under the turned around liner, leaving the silicone coating on the face. The self-wound rolls are then micro-perforated.
The Proper-LL linerless applicator built by ILTI (Figures 7.6 and 7.8) allows easy changeover between conventional pressure-sensitive and linerless modules: a trolley-based plug and play unit can be exchanged in under a minute.
In trials to date, line speeds up to 500 bottles/minute have been achieved, although ILTI says that double this speed is possible upon request.
Multiple label types can be applied on the same container.
OTHER LINERLESS TECHNOLOGY
It is worth noting a number of other linerless technologies introduced in the recent past. Introduced by companies such as NuLabel and Polykote, these use heat-activated adhesive materials. Avery Dennison has an adhesive that remains pressure-sensitive after application.
Figure 7.6 - The ILTI Proper-LL linerless applicator
Figure 7.7 - The purpose-built RG20 converting module that transforms standard self-adhesive material into a single linerless label web
Figure 7.8 - ILTI linerless applicator on a production line