Finishing & Screen Printing

Interface problems are now a thing of the past: A new complete system combines pretreatment, coating and drying

Wednesday 23. January 2013 - Trade fair preview on ICE Europe from 19th to 21st March in Munich

The coating of foils, textiles or metal requires complex process technology that encompasses three different processes: Corona pretreatment, a spray application (of anti-fog for example), release agents or hydrophobization, and drying of the functional coating. Previously, the different procedures were either carried out separately, or the individual machines were cobbled together into an improvised production line. However, this resulted in unpredictable interface problems. In addition, the functionality of the coating was not guaranteed, responsibility in the event of a fault was not clarified, and the production costs could not be calculated. This led Ahlbrandt System GmbH to develop, in the shape of the “Web Process Line”, a complete solution from a single source that combines all three components. It works with the proven corona technology, allows an extremely thin, water-based spray application and dries streak-free. This makes the Web Process Line more energy-efficient, more resource-saving and financially more economical than processing the substrate in individual machines, and it is setting a trend in Germany. The company will be presenting the system at the ICE Europe trade fair.
“The advantage of solutions from a single source is that they work reliably because all the components are tailored one hundred per cent to each other”, explains Dipl.-Ing. Michael Hoppe, Product Manager at Ahlbrandt System GmbH. Since all the components of the Web Process Line come from a single source, the customer can rely on delivery on time, at a fixed price and on comprehensive technical support. In addition, the system’s ROI can be calculated in advance because all data such as the volume of chemicals, raw materials and energy that are to be used is known.
An application spectrum from 0.5 to 25 g/m2 for many different substrates
So that the spray application adheres better, the substrate initially undergoes corona treatment. This means that electrical pulses are fired at the often water-repellant, non-polar and electrically isolated surfaces. Dispersive and polar interactive components result in higher surface tension, the result of which is that dyes, paints, solvents or emulsions remain permanently adhered to the substrate.
For the sake of the environment, Ahlbrandt has designed the Web Process Line so that only water-based chemicals are processed. These are atomized via several rotors arranged in parallel and are applied evenly onto textiles, fleece, paper, metal foils or synthetic foils. This special arrangement produces overlapping spraying fields that guarantee an even and highly effective application. The tolerances with coating weights of 0.5 to 5 ml/m2 are extremely low, and this is reflected positively in terms of material consumption. At the same time, it allows a very broad application spectrum that can be between 0.5 and 25 g/m². The spraying volume is automatically dosed and is adapted to the web speed, resulting in a minimum amount of chemicals and drying energy being required.
On absorbent substrates such as paper or textiles, the coating can be left in droplet form. On foils or metal strips, the droplets are transformed into a homogeneous film with the aid of a roller. The spray application is then dried with hot air or – if appropriate for the method of drying – also with the aid of infrared. This is done streak-free for up to six meters of substrate width, which makes the drying process extremely energy-efficient and resource-saving.
The system is always individually configured in close collaboration with the customer. “If for example the customer wants a double coating with different chemicals that interfere with each other, the two spraying systems are simply arranged separately and two dryers are installed”, explains Hoppe.