The advantages of functional labels

Tuesday, 01 April, 2008

No longer are they merely decoration. Labels today are performing more and more functions. In addition to the marketing aspect of a finely printed label for a brand, labels are also used to guard against counterfeiting and tampering. Advances in print technology make it possible to integrate new functions into labels.

Shrink sleeves are becoming increasingly popular for the decoration of containers. The sleeves, applied over the container and then treated under heat in a shrink tunnel, conform to any shape of product. This type of decoration is ideal for waisted plastic bottles of the type popular for dairy products, for example.

Shrink sleeves have high growth potential. They conform to any shape, decorate the full surface including shoulder area and can even also secure the cap. In contrast to directly printed containers, there is no need to hold stocks of preprinted products. One advantage for the food industry is that the labels are applied without glue, eliminating a cleaning operation on the machine. Shrinking takes place in a hot-air, vapour-shrink or infrared tunnel. Three main materials with different shrinkage properties are used for the labels. In Europe, PVC (polyvinyl chloride) is used in 50% of cases. Depending on type and manufacturer, PVC displays a shrinkage rate of 45 to 66%. The greatest amount of shrinkage is offered by PET at almost 75%. In Japan, the world’s biggest market for shrink sleeves, PET (polyethylene terephthalate) is the leading material ahead of OPS (oriented polystyrene), which has a high shrink rate of 70%. One disadvantage of OPS is its limited ‘shelf life’, requiring climate-controlled storage at both the label printer and the processor. OPS is mainly found in Asian markets such as Japan, Korea and China.

All materials are reverse printed on the inside to protect the colour from scratches. They are glued to form a sleeve and delivered on rolls. One challenge for printers is to allow for shrinkage of the different materials in the designs so that the print image exactly meets marketing requirements after heat treatment. A large role is also played by creasing, which must be avoided at all costs.

Flexible material

Film labels need to be both flexible and stiff. Up to now, these properties have only been attainable individually using polyethylene or polypropylene. Now a new polyolefin film has been developed specifically as a label material for printable packages such as tubes or cosmetic containers. The films conform to the often complex shaped containers, with the stiffness of the material guaranteeing reliability during application and high dispensing speeds in all-round labelling. Thanks to their good printability, even unusual design challenges can be implemented.

Space for information

Multilayer labels are the trend for promotion campaigns. For a campaign by Coca-Cola Belgium, for example, two-layer labels were produced which can be applied by conventional standard labelling machines. The upper panel with viewing window is integrated in the basic label and can be turned through 360 degrees. The information printed on the basic label becomes visible by turning the panel. The labels offer 75% more space for product information or recipes.

Information labels or bottle tags as on-pack promotion items offer space to place advertising messages attractively on products. They can range from three- to five-page leaflets to mini brochures. The info labels are applied by standard labellers. Dyes and paints are put to versatile use for special effects in label printing, including thermochromic dyes which only become visible in a certain temperature range, or dyes which shine in the dark.

Security for customers and manufacturers

Both concealed and visible features are used in the area of security labels. For consumers, it is important to be able to recognise from visible features such as holograms whether a product is genuine, without having to use aids such as scanners or UV lamps. However, as counterfeiters mainly attack the visible features, additional non-visible security features are used in sensitive areas.

A combination of anti-tamper and counterfeit protection serves firstly as an indicator of tampering and secondly as proof that a product is genuine. According to the World Health Organisation (WHO), a combination of visible and concealed features increases protection against counterfeiting for medicines, because the more security features a product has, the more likely it is that a counterfeiter will overlook a feature or fail at one point.

For packages, cap seals are available which make tampering evident by the irrevocable appearance of a logo or wording (void effect). Concealed features also include micro and nano texts, true-colour coding and concealed laser-readable security prints.

Guaranteed refrigerated

Consumer safety is also to the fore in a new development designed to document the integrity of the food refrigeration chain.

For meat and poultry, it can be dangerous to health if refrigeration is interrupted for too long. The new label, which indicates the freshness of the food in several stages, uses temperature-sensitive printing dyes.

The time-temperature indicators show at a glance whether perishable products have been properly delivered and stored. They deliver clear evidence of whether cold chain integrity has been maintained by documenting the effects of temperature fluctuations as a function of time. Each indicator is tailored to the specific requirements of a product in terms of shelf life and storage conditions.

The labels are applied to the packaging on fully automated equipment. A UV filter is activated and the tracing code is applied. The technology is based on pigments which change their colour over time and when temperature fluctuations occur. The label or print has a reference colour as well as the time-temperature indicator. After activation by a suitable light source the indicator turns dark and then becomes brighter over time and when temperature fluctuations occur. If the ambient temperature exceeds the specified temperature, the brightening process speeds up. The shelf life of the product has expired when the activated colour indicator is brighter than the reference colour. Once-only activation ensures that the colour label cannot be tampered with.

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