The company, which has developed stamping foil systems especially for overprinting, demonstrated this technique at Drupa 2004.
First, the foil packaging is hot stamped before being overprinted. This process was presented at a live demonstration at the event.
On a Nilpeter narrow web-printing machine, beverage bottle labels were decorated with cold stamping foil in rotary application. This, says Kurz, gave visitors a close up view of how plastics can be upgraded with a metallised stamping foil using the flexo printing process.
Cold stamping has undergone continuous development over the past years and today the process is well established and used successfully in, among others, the label sector. Kurz believes that the cost-effectiveness of cold stamping has increased the size of its potential market to include products that typically have not been decorated in the past.
In particular, labels used in the food and beverage industries are all now candidates for decoration by the cold stamping process. Inmold and shrink labels that have, until now, largely been excluded from hot stamping due to their temperature sensitivity, can now be decorated by cold stamping.
This simple but efficient upgrading allows new design options in the broad field of flexible packaging in the food, confectionery and ice cream. Even the replacement of printing with metallic pigments or metallised papers/plastic films is now conceivable - the in-line cold stamping process delivers superior metallic brilliance and gloss.
The technical diversity of this process requires intensive project support and close cooperation between users and their suppliers. Among the many factors influencing the printing result are the base material, the stamping foil, the quality of the embossing, the printing process chosen and the colours used.
Stamping foil formulation depends upon which particular printing process is used and whether UV cured or conventionally dried inks are used. Kurtz says it can offer advice on harmonising application systems and materials to be employed and conducts tests on a customer's behalf to ensure the quality of the finished part.
The company also claims that the process opens up the possibility of safer, tamper-free packaging. The firm recently launched a comprehensive brand protection product range with many component combination possibilities, including a wide range of difficult-to-copy OVDs (optical variable devices) such as holograms and the high-tech Trustseal security option.
Kurz has also developed security features based on a complex, hard-to-imitate foil technology. Diffractive effects such as customised-design foils with continuous, ultra-fine geometric patterns, plain foils with multi-angle rainbow colour effects or single-image holograms are available from Kurz on transparent foil.
Transparent diffractive foils are difficult to imitate because specialist foil-related know-how is required to manufacture them. Secondly, they serve as an additional security feature for protecting important readable information against counterfeiting, like personal data, photos, of manufacture or use-by-dates and warranty codes. The information remains clearly readable at all times but it is protected: any tampering of the foil to falsify the stored data and information will be readily recognisable.
During the manufacturing process, single images, for example a Trustseal, can be positioned precisely in the x and y directions relative to the demetallised design. This combination of OVD and demetallisation - which Kurz refers to as 'dual security features' - is then transferred with high edge definition onto the product to be protected.
This technology can produce type with letters approx. 0.5 mm in height, which would not be possible to simulate with a stamping die. Both positive and negative designs can be implemented using demetallisation, and according to Kurz, the range of possibilities is virtually unlimited.
In contrast to fully metallised hot stamping foils, demetallised hot stamping foils are only partially covered with an aluminium layer. Geometric patterns as well as digits, letters and type with a filigree structure can also be realised.
The market for transparent foils has increased rapidly in the last few years. Partly this is due to growing awareness from manufacturers that they must do their utmost to ensure the security of their product. More and more are looking to foil as a means of achieving this aim.