Maschinenfabrik Max Kroenert

Fit for the future – the Technology Center

Kroenert Technicum Machine
The Kroenert, BMB and Drytec Technology Centre made headlines as early as 2005 with the presentation to the public of the widest, fastest R&D machine for coating and laminating in the world. With a working width of up to 1300 mm and a maximum speed of up to 1610 m/min, this machine was unique. The tests performed here resulted in the nowadays standard production speed of 1000 m/min or more for PSA label materials.

Since March 2010 the line has made available extended functionalities, setting new benchmarks in the converting industry. . Machine layout, coating process and drying were reworked.

Machine Layout
The newly constructed drive permits not only exceptionally fast, but also exceptionally slow operation. The previous speed range of 4 to 1610 m/min has been extended; it is now possible to drop machine operating speeds down to 0,5 m/min to allow thick coating and drying at lowest speeds. Working width varies between 250 and 1300 mm.

Coating Process
Since the conversion of the station, the various coating heads permit more than 70 coating processes.

For example, new equipment includes a nip coating head with coating table just before the dryer for the application of low-viscosity and thick coatings. Porous substrates such as non-woven materials, the thinnest thermoplastic films or membrane foils can also be coated in this way. The short web length between the new coating head and the dryer avoids web tensioning problems.

This coating head is suited for coating in direct processes as well as leveling coatings and also for reverse roll indirect applications for contour coatings and intermittent coatings.

Further coating techniques are also available for curtain coating. The Multi Wet Curtain allows up to three layers of Wet-on-Wet coating. A Single Wet Curtain allows the setting of the distance between the nozzle and the web to between 0.1 and 250 mm. Thanks to Curtain and Bead Coating the applications available with contact-free coating techniques have been substantially extended.
Curtain and Bead Coating

Characteristic Curtain Coating Bead Coating
Pre-dosed: Yes Yes
Contact-free: Yes Yes
Distance nozzle - substrata:70/150/250 mm 0,1-0,3 mm
Speed: 100 – 2.500 m/min 0,1 – 300 m/min
Viscosity (measured from 103 to 104s-1):
300 - 50 mPas 800 – 10 mPas
Surface tension: <40...30 mN/m <30...50 mN/m

Radiation drying
Much has also been accomplished in the area of drying. In addition to the previously available curing of 100 % UV-curable materials such as silicon, acrylate, lacquer etc, hybrid systems can also be processed. The new convection dryer configuration enables the thermal evaporation of water and solvents in the drying channel. In addition, the hybrid system is integrated inline by means of UV rays.

A drying channel of 18 meters and a UV dryer with five UV radiators, are available for thermal drying in atmospheric conditions or with inert gas (nitrogen). The integrated, patented air-cooling permits the processing of heat-sensitive PVC, PP and PE films.

A further innovation lies in the optimized positioning of the IR radiator, as a supplement to convection drying. By adding IR radiators of the long to medium wave spectrum, the drying of aqueous materials is supported in section 1, and in the last drying section, further IR radiators reduce the residual liquid remaining from solvent and aqueous coatings. These measures have led to a significant increase in performance and quality levels.

Do you still have some questions about the new R&D line ? Please contact
Michael Schmalz (+49 40 853 93 160, michael.schmalz@kroenert.de) or
Dr. Wolfgang Neumann (+49 40 853 93 180, w.neumann@kroenert.de).