PolAR

The aim of the project is to develop a new process for making films anti-reflective. A plasma-etching process, which up until now has been utilized for small and compact optical parts, will be further developed for modifying film surfaces.
A key aim is to realize this process in a continuously operating plant (roll-coater).

The project work involves:

• the testing and evaluation of plasma and ion sources that can guarantee effective etching on defined films;
• the determination of parameters for generating anti-reflective structures on PET film, TAC film, and three further film materials by optimizing initial layers (layer material and thickness) and etching parameters;
• the construction and testing of a roll-coater with a plasma source or ion source, with the aim of generating the structures in a continuous process;
• the manufacture and testing of prototypes.

Plastic films are nowadays produced in enormous quantities. The biggest user is the food packaging industry. In addition there is a very wide range of applications in high-tech products. These products and applications include packaging, protective encapsulation of medicines and electronic goods, decorative elements, and also the realization of complex functions in displays and solar cells. The increasing use of all types of mobile electronic devices has in particular seen the last-mentioned applications grow in importance.

In most cases the optical properties of the films must be customized for particular applications. Films that are anti-reflective are in demand. Due to the different refractive indices of plastics and air, light is partly reflected on the front and rear sides and this is even so for transparent films. For widely-used PET the reflection is about 12 percent, and this value is higher than for glass.  

Polymer films with anti-reflective properties can be used in all situations where large areas need to be made anti-reflective at favorable cost. Typical fields of application include glazing for display cabinets and shop windows, large optical elements for projection equipment, and car parts. Anti-reflective and anti-fog surfaces are also of interest for, for example, sports glasses, windscreens, and displays.

Decisive for commercial use, particularly for medium-sized companies, is the availability of reasonably priced anti-reflective films. The project is tackling this issue in two ways. Firstly, the plasma-etching process has the potential for producing good quality products at low production cost. Secondly, the work is focusing on realizing a roll-to-roll coating plant. This type of machinery is ideal from a logistics standpoint and can be universally used for different roll products. At the same time, the continuous operation and simultaneous running of all necessary processes also offer the potential for favorable-cost production.

The idea for the project originated from the Fraunhofer Institute for Applied Optics and Precision Engineering IOF. The base processes for successfully generating anti-reflective structures on compact plastic materials had already been developed at the Fraunhofer IOF in preceding years. Direct contact with film manufacturers (Southwall Europe and Island Polymer) made it clear that there was a need for anti-reflective films that were not currently being manufactured by European companies.

The consortium that has been brought together to successfully and efficiently realize the project work comprises partners with complementary experience. All stages of the project involve leading companies with the necessary industrial and technological expertise. The evaluation of various plasma sources at the start of the project is being undertaken with the support and technology of Roth&Rau AG. Simultaneously the research organizations are studying the mechanisms that lead to changes in film topography on exposure to plasma. Another main area of work involves the construction and testing of a roll-coater technology for structure generation. This work mainly involves the Fraunhofer FEP, Roth&Rau AG, and Southwall Europe GmbH.

A parallel development concerns studies to mold anti-reflective structures from a film master. The transfer of structures in this way is of particular interest for optical lenses and spectacle lenses and is the focus of work being undertaken by the Fraunhofer IOF in collaboration with Leica Microsystems GmbH and Rodenstock GmbH. As users of modified films, Johnson Controls GmbH, NOWOFOL Kunststoffprodukte GmbH & Co. KG, and SeeReal Technologies GmbH will prepare specifications for anti-reflective /anti-fog and anti-reflective / hydrophobic combinations and then test and evaluate the film samples.

The project consortium covers a value creation chain which includes the evaluation of the starting films, the construction of suitable plant technology for process development, and the testing of performance on prototypes. The industrial partners can be divided into film manufacturers, plant / ion source constructors, coaters, and users.

Optical components and films made of plastic are typically used in Germany for products made by small and medium-sized companies (SMEs). In a competitive marketplace the SMEs require maximum functionality and usage value for their products. The research results form the basis for innovative and efficient optical components which are required, for example, for product developments such as optical sensors for IT, communication technology, and medical technology. From the standpoint of the participating companies, it is strategically important for European industry to undertake its own development activities in the area of display technology and precision optics and to maintain a certain independence from market leaders from, for example, the Far East.

The consortium partners will make use of the project results for the following:

• manufacture and marketing of anti-reflective films as a favorably-priced mass product;
• use of specially modified films and nanostructuring on plastic in combination with layers on high-quality optical products;
• development and marketing of optimized plasma and coating technology for users who wish to modify their products via nanostructuring.

The PolAR project is in principle still open for further partners, providing the interests of the companies who have already supported the project financially and with R&D assistance and the interests of the participating institutes are maintained.