Focus on Addition of Functional Properties to Films: At the K fair 2016 in Düsseldorf, “Weitmann & Konrad GmbH & Co. KG‘ showcases a variety of applications giving films special properties – true to the motto “Don’t play – work with precision!”. The focus is on adding functional properties to films through non-contact spray application of anti-blocking, anti-fog or anti-static additives. Anti-curling uses and the application of primers supplement varied the application options.
The WEKO motto “Don’t play – work with precision!” underscores the fact that the WEKO-Fluid-Application-System is no gadget but a high-precision system applying finishing chemicals exactly metered and clean onto the plastic film web. WEKO – on the market for more than 60 years – has specialised in precise and non-contact applications of minimal liquid or powder quantities on plastic film and other material webs.
Many flexible films are finished with special surface-active substances to optimise the physical properties. Many of the world’s renowned plastic film manufacturers already rely on the WEKO coating technology and achieve significant cost and quality advantages compared to the use of batch additives.
The extruded film webs are finished with a very thin liquid functional coat immediately following the extrusion process. Contrary to batch additives external coating neither affects the behaviour of the melt in the extruder nor the flow characteristics at the extrusion nozzle and not even the barrier effect, and thus the thickness of the different film coats.
The function is effective immediately after application and retains its effectiveness continuously even after very long storage periods. Another advantage is that the film retains its transparency, entirely without opaqueness.
Release agent application – the classic
WEKO application systems are most often found in the area of release agent coating of PET film. These thicker single or multilayer films are used for thermoforming trays. When manufacturing products by thermoforming, silicon emulsions make it easier to release the trays from the moulds and to destack the final products. Thanks to the minimal and very exact application of anti-blocking agents uniform and high-quality plastic trays are produced. At the same time, the thermoforming process represents cost benefits by increasing the cycle rates, reducing downtimes and minimising the release agents used.
Polyolefins – the divas
Naturally, in addition to PET films, polyolefin products can also be coated. Because of the surface energy water-based coating of polyolefins usually requires corona pre-treatment. From a surface energy of the film of 38-40 mN/m very thin, uniform coats can be produced with dry thicknesses in the nanometre range. Common applications in this area are anti-fogging, antistatic and antibacterial coats.
Another use is the reduction of curling effects of co-extruded blown and flat films. Due to different cooling characteristics of the individual film layers, tensions – and thus significant rolling tendency of the film – may occur after extrusion. Extremely uniform and controlled application of a minimal amount of moisture compensates the tension and results in considerable quality enhancement.
Primer – the young and the wild
The application of primers for extrusion coating represents the latest application area. For example, a bonding agent is required when a PE coat is co-extruded as sealing coat onto PET film. With the WEKO application system this primer can be applied exactly and uniformly onto the carrier film, even at variable speeds. Application of the primer takes place without contact and is merely pulled into a uniform film through a smoothing roller. Compared to the conventional method, using anilox rolls and chamber doctor blade systems, minimal and constant liquid application can be produced with the non-contact WEKO process. Thanks to the minimal application, the cost for the primer and also for the operation of the dryer can be significantly reduced. Lower investment costs and reduction of the process costs make the system particularly attractive for new facilities.
Rotor application systems – maximum precision
WEKO has specialized in applying finest surface films on material webs. Rotors arranged in a row within a rotor carrier and rotating at high speed ensure a non-contact application of liquids. The rotary movements of the rotors and the resulting centrifugal forces produce a uniform flow of finest micro-droplets. This special technology allows the application of even the smallest amounts of fluid precisely, reproducible and adapted to the speed. In addition to its wide dynamic range, these systems excel through outstanding service-friendliness. WEKO application systems represent both highest industrial requirements and also cost and ecology-minded production.
About WEKO – Weitmann & Konrad GmbH & Co. KG
The WEKO experts offer support worldwide with the choice and integration of WEKO non-contact minimal application systems in the production process. They help customers achieve clear benefits and cost advantages with the materials to be processed and/or in the process itself. Comprehensive services, such as test series at the WEKO technical centre and high WEKO service standards, complete the WEKO offering.
In addition to the main office near Stuttgart WEKO maintains two production locations in Germany and Brazil, own sales and service subsidiaries in Italy, the United Kingdom, the U.S., and Brazil. Furthermore, WEKO collaborates worldwide with agencies marketing the products and offering the proven WEKO service standard in addition.
Technical contact:
Markus Klempin
Product management
Tel. +49 (0) 7 11-7 98 8-205
