The Eislingen-based Zeller+Gmelin GmbH & Co. KG group, which includes numerous printing ink specialities for niche markets in its range of products, has developed a new generation of inks for metal printing. The company specialize in the development and production of radiation curing ink systems and possesses wide experience with printing inks for moulded packaging and packaging printing with non-absorbent material. They have applied this know-how to the field of metal printing and have developed the Eurapid O3 series of inks for printing lacquered and unlacquered metals by both the offset and dry offset (indirect letterpress) processes.
In the future, Zeller+Gmelin intend to expand its activities in this market segment, and the company has strengthened its team in the Technical Service Centre with the addition of Michael Rakoci whohas many years experience as an application engineer for a machine manufacturer in the specific field of metal printing.
The Eurapid O3 ink series are conventional printing inks with a high levelof flexibility and intense colour strength. They feature very good fastness and resistances properties as well as very good scratch resistance. The main application areas are decorative printing of metal packaging as well as direct printing on aluminum tubes and aerosol cans.
A perfect example which demonstrates the special qualities of the new ink series is an aluminium beer bottle produced at Szenna Pack Kft. (see images). The production plant of the Hungarian company is located in County Somogy – situated around 200 km from Budapest and 60 km south of Lake Balaton. The bottle was produced on a Mall+Herlan GmbH production line which was installed in 2005.
Mall + Herlan, who are located in Pfinztal near Karlsruhe, manufacturesproduction lines for aluminium tubes, aluminium aerosol cans, cartridges, marker pens and rigid tubes for cigars. These production lines are capable of impact extruding, lacquering and printing many sorts of cylindrical aluminium products. The printing units which are integrated into the production lines are supplied by the Polytype Company, which is also the majority shareholder of Mall+Herlan.
Production of these unusual beer bottles used aluminum tubes with a corresponding length which were produced by cold forming. They were then brushed externally and put into a cleaning bath. Afterwards a protective coating was applied to the inner surface and a coating of half-matt silver lacquer was applied externally. After drying, the motif was printed on a total of seven printing units. In order to achieve best possible opacity, the white basic ink was applied in two stages. The first application of white white was printed with a 75 percent screen with the second application being a 100% solid. The printing of the red coloured areas was also shared between two printing units. With a reduced colour application in the upper part of the bottle and the optimised interplay between the flexible printing ink and the printing plates, a consistent colour impression (no frosting) was achieved even after moulding of the bottle neck.
The remaining three printing units were used for printing a black screen as a base for the darker areas as well as a grey for the froth of the stylised beer mug and the black letters.
This new generation of metal printing inks requires a drying time of seven minutes at a temperature of 170°C. After the drying the inks the process continues with the application of a varnish coating followed by further drying. Finally the machine molding of the bottle neck and rim roll takes place.
The aluminum bottles printed with Eurapid O3 intensive colors exhibit a high print quality and dot sharpness with the use of laser-engraved printing plates making a contribution to this. The plates were supplied by the HL-Repro company from Denmark. Laser engraving offers the advantage that different relief heights for surfaces and halftone dots can be achieved and this in turn provides optimised conditions for ink transfer. This in combination with Zeller+Gmelin’s Eurapid O3 series of printing inks results in a brilliant, flexible, abrasion resistant and chemical resistant printing ink film.
Moreover, the good deep drawability of the inks means that the ink film does not become brittle ensuring no chipping of the ink film after deep drawing and final sterilisation even in those areas which have been formed most.
Regarding light fastness, the inks have a minimum scale value of 6 (according to DIN 16525). They are resistant to solvent mixtures (DIN 16524) as well as heat sterilisable at 131°C for up to 30 minutes and temperature-resistant for 10 minutes up to 180°C.
These highly unusual bottles were filled at the Swabian private brewery Hilsenbeck with the “Gruibinger Brunnenbier“ brand of beer, an unfiltered, i.e. unprocessed beer with round, full-bodied taste and a fine hop note.