Textile finishing in classic dip tanks requires large amounts of drying energy in light of the immense water volumes used in the dipping process, which often lead to high water loads in the dryer. In contrast to this, spray application offers precise and minimal dosage, whilst simultaneously saving energy, water and chemicals and enabling the one-sided or even double-sided bi-functional finishing of textiles and tiles. In many cases, an upstream corona pretreatment offers particular advantages, since it leads to the quicker and more even absorption of spray chemicals on certain substrates. Until now, however, such systems have not been available from one single source. This led Ahlbrandt System GmbH to develop a complete solution from a single source that combines the components of corona pretreatment, spray application and drying - the Web Process Line. 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 a dip tank, and it is setting a trend in Germany. The company will be presenting the system at the Techtextil trade fair.
'In comparison with the dip tank, the Web Process Line finishing procedure enables savings of up to half of the application volume', explains Dr. Alexander Rau, Product Manager at Ahlbrandt System GmbH. 'The system has been designed to save resources, ensuring the economical use of both substrate and energy.' The system also unites three machines and thus several work processes in one. This guarantees safe functioning since all components are precisely adjusted to each other. 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.
Application spectrum from 1.0 to 150 g/m2
In order to ensure that the spray application adheres better and guarantees even absorption, non-hydrophilic substrates initially undergo corona treatment. This means that electrical pulses are fired at the surfaces. Dispersive and polar interactive components result in higher surface tension, thus leading to improved and more even substance diffusion into the fabric and better adhesion 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 or fleece. This special arrangement produces overlapping spraying fields that guarantee an even and highly effective application. The tolerances with finishing volumes of 0.1 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 1.0 and 150 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.
Subsequently, the spray application is dried with hot air. 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 dryer can also be equipped with additional infrared radiators, which enables quicker material heating with thicker fabrics, thus reducing the time required in the dryer.
The system is always individually configured in close collaboration with the customer. 'If, for instance, one side of a textile is to have different functional properties to the other, requiring a double-sided finishing process with different chemicals, this is possible, even if they interfere with each other. In such cases, the two spray systems are simply arranged separately, with the integration of two dryers', explains Rau. This enables the production of bi-functional textiles, which would not otherwise be possible. The speed of the system can also be adjusted depending on the specific substrate. Fleece, for instance, requires quicker web speeds of up to 100m/min, whilst textiles with 30 to 40m/min pass through the machine at a considerably slower pace.
