International. The Fraunhofer Institute for Organic Electronics, Electron Beam and FEP Plasma Technology has succeeded in developing a new technology for the production of ultra-smooth polymer films as part of the "OptiPerm" project.
This project received funding from the European Union and the Ministry of Economy, Labour and Transport of the State of Saxony (Grand Bargain No 3000651169). The technology, which was previously demonstrated in samples in A4 format, has now been successfully transferred to a roll-to-roll process with even higher surface quality. These results were first presented at the AIMCAL conference in Munich, Germany in June 2018 by Dr. Steffen Günther.
Smooth surfaces with low defect densities are of great importance for many application areas, whether they are decoratively coated vehicle bodies, high-gloss and dirt-resistant furniture, or ultra-soft metal and plastic films that serve as substrates for high-tech industries. Particularly in the latter case, the subsequent finishing stages can only exhibit their full potential if the quality of the substrate surface is also at a very high level.
For example, films for encapsulation of electronic components need thin permeability barrier layers manufactured by a vacuum coating process that prevents against the penetration of oxygen and moisture. Defects on the surface of the substrate would compromise these thin coatings.
The deposition of active electronic layers, for example for OLEDs or touch screens, requires ultra-smooth surfaces to ensure reliable capabilities, such as light emission and conductivity over large areas.
Fraunhofer FEP scientists have developed a new method for creating ultra-smooth surfaces, called the smoothing film approach. "This innovative process does not require any special processing environment and can therefore also be used under standard factory conditions," explains Dr. Steffen Günther, Project Manager at Fraunhofer FEP. "Expensive cleanrooms are not necessary for this process."
With this new approach, a wet coating is first applied to a flexible substrate. Immediately afterwards, the coating is covered when it is still wet with a second film, the smoothing film. Subsequently, the wet coating is cross-linked through the smoothing film by an energetic drying process. Therefore, an electron beam is used in Fraunhofer FEP due to its high performance with respect to the cross-linking ratio. The smoothing film can be lifted directly after cross-linking or remain on top of the coating as protection until the following subsequent processes take place. To reduce the costs of smoothing films, their reuse was examined. The scientists were able to show that even after reusing the smoothing film ten times, no increase in the density of the defect or a decrease in surface quality was observed.
Data Source Provider: Fraunhofer Institute.
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