Extrusion Asia Edition 1-2019

用于染色方案的绿色荧光蓝光激发 (© Fraunhofer IAP) Green fluorescence of a dye solution excited with blue light (© Fraunhofer IAP) 漆带的荧光 (© Fraunhofer IAP) Fluorescence of a lacquer strip 即采用电子辐射改变聚合物的分子结构。可以实现弹性模量 的自适应或热阻隔等效应。过去已提供了化石基聚合物薄膜 的证据。目前正在研究生物基材料也能在多大程度上确定这 种影响。 Steffen Günther博士解释道： “这种处理在大气压 力下发生，而不是在真空状态。在夫琅和费FEP研究所的实 验生产线atmoFlex 1250用于此目的。由于其宽度1250mm， 在带材速度高达150 m/min时能实现高产量处理薄膜。这两个 方面都使得薄膜的处理非常经济高效。 与他们的研究一起，三个夫琅和费研究所希望为避免浪 费作出显著的贡献，与此同时增加食品的保质期。所开展的 开发生物基包装薄膜的方法旨在为客户、环境和生产商都带 来积极的效益。 steps such as adhesion. Amino functionalization can also be li- mited to the edge area of packaging films using gas-phase and wet-chemical process steps and used for laminating the films. Safe food through physical disinfection For a longer shelf life of food, the packaging must be free of contaminating germs. Depending on the material, microorga- nisms on packaging are usually inactivated by heat, gas, ioniz- ing or UV radiation. Low-temperature plasmas used at IGB are a material-friendly alternative to sterilization at high tempera- tures. They are not only suitable for creating layers, but can al- so inactivate microorganisms due to reactive molecules and UV radiation in the plasma process. “With plasma sterilization, even highly resistant endospores of different Bacillus species become unable to reproduce after relatively short treatment times”, says Barz. In addition, scientists at Fraunhofer IGB have further developed UV treatment in order to minimize the number of reproductive microorganisms on surfaces. With new, specially designed ex- cimer lamps or the latest UV LED technology, packaging films can be sterilized quickly and effectively. These processes can be scaled up on packaging machines and adapted to individual re- quirements. Rollcoater for high-speed finishing The market for packaging films is extremely price-sensitive. Fraunhofer FEP devotes itself to this aspect by developing highly productive finishing processes, which are characterized in particular by very high speeds. One example is the produc- tion of transparent barrier layers of aluminum oxide against ex- ternal influences such as moisture or oxygen on plastic films using plasma-activated high-rate deposition at web speeds of several meters per second. Therefore, Fraunhofer FEP operates so-called roll coaters, which can efficiently coat film material with a width of up to 700 mm and web lengths of several kilo- meters. The researchers are currently working on qualifying this established technology for use on biobased materials. A further example is the modification of polymer materials when they already exist as films. For this purpose, Fraunhofer FEP operates a roll-to-roll system that uses electron beam irra- diation to modify the structure of the polymer molecules. Ef- fects such as the adaptation of the modulus of elasticity or the thermal resistance can be achieved. The proof for fossil-based polymer films has already been provided in the past. The extent to which the effects can also be determined with biobased ma- terials is currently being investigated. Dr. Steffen Günther ex- plains: “This treatment takes place at atmospheric pressure and not under vacuum. The pilot plant at Fraunhofer FEP atmoFlex 1250 is used for this purpose. Due to its web width of 1250 mm, a high throughput in the treatment of films at web speeds of up to 150 m/min can be achieved. Both aspects allow a very cost-efficient processing of the films.” With their research, the three Fraunhofer Institutes want to make a significant contribution to waste avoidance. While at the same time increasing the shelf life of food, the approaches presented for the development of biobased packaging films are intended to generate positive benefits for customers, the en- vironment and producers. Fraunhofer-Institut für Organische Elektronik, Elektronen- strahl- und Plasmatechnik FEP Winterbergstr. 28, 01277 Dresden, Germany www.fep.fraunhofer.de 27 Extrusion Asia Edition 1/2019