Automated Lab Coating Platform Targets UV Coil Coating Applications
Developing new coating formulations and coating processes is traditionally a very time consuming process involving many independent chemical variables and process parameters, such as UV curing parameters. Delivering results close to those achieved in pilot lines is an important driving force for the coatings industry in developing new technologies and systems for lab coating research.
The high throughput experimentation company, hte Aktiengesellschaft in Heidelberg, Germany, is a young, but fast-growing company delivering new, automated lab solutions for formulation and materials research including software solutions and contract research services.
Due to industry demand, hte developed a novel, high-throughput coating platform integrated into an overall informatics solution that is currently being installed in the first customer’s laboratories. "The main challenge for us really has been the wealth of parameters our customers wish to vary automatically on such a platform", says Torsten Zech, project leader for the development at hte. These variables include substrate type and properties (from thick rigid substrates to very thin and soft foils), very different coating formulations (water-like and very viscous formulations), coating speeds, and, of course, the whole variety of curing parameters.
Therefore, hte had to develop a new platform concept to meet all these requirements. At the core of the coating platform, hte designed and implemented a high-speed transfer system for transferring the coating substrates between the individual processing modules. Two substrate holders (for rigid and flexible substrates) can move independently through the platform allowing very fast processing of the coatings. The coating module connects to the other processing modules via a high-speed substrate transfer system. Robots provide substrates, formulations, and the necessary coating tools to the coating module automatically. Following the coating application, the samples can then be processed in an arbitrary sequence in two UV curing units and two IR drying units. At the end, the coated substrates receive barcodes for identification in the downstream processes.
A powerful articulated-arm robot picks substrates of different types and thicknesses from stacks and delivers them to the substrate holders. After processing, each barcoded substrate is placed into the substrate hotel, a holding area, prior to characterization and performance testing. A customized 8-needle liquid handling robot delivers formulations to the substrate. Using disposable tips to transfer formulations from heatable stirring plates (up to 120 positions) to the substrate avoids the need for cleaning.
An innovative coating process using proprietary application tools allows the application of very thin and homogeneous films. The tool can generate different coating patterns (number of stripes, full-width coatings etc.) and properties such as film thickness. Furthermore, the coating speed is freely adjustable up to 1 m/s, by moving the substrate instead of the tool. As two substrate holders are available, an automated switch from rigid to flexible substrates is possible. Additionally, multilayer coatings are possible. The tool is cleaned and exchanged automatically after the coating application.
One of the main design goals of the workflow was very fast drying and in particular, UV curing of the substrates following coating application, as it is required in many coil coating or other inline applications. By using the unique and dynamic transfer system concept, the substrates transport within a few seconds to the curing units. For example, at a maximum speed of 4 m/s, the substrate reaches the drying or curing unit after not more than 0.5 seconds following the coating application. As such, industrial coating conditions, like those found in coil coating or the application of reactive coatings, can be simulated.
Two UV curing units can operate individually at different conditions. "As we wanted to achieve close-to-industrial conditions, we chose the Light Hammer® 10 units from Fusion UV for integration. It has been a pleasure for us to work with Fusion UV, as they were very responsive and helped us with all our integration questions. We have now achieved a seamless integration allowing arbitrary and reliable UV curing conditions", adds Torsten Zech. Furthermore, there is the option to cure under inert conditions by using a nitrogen flush.
For drying, two IR units can operate independently. It is possible to homogeneously heat the full substrate surface to the target temperature by adjusting the transfer speed and IR power. As such, substrate temperatures can reach up to 300 °C. Furthermore, there is an option to heat the substrates from the back side to simulate induction heating. As the transfer system is bi-directional, a variety of curing sequences are possible. For instance, the substrate could pre-heat in an IR unit, then apply a thin film, and then dry/cure in two steps, first in the IR units and then in the UV units.
However, for hte it doesn’t end with developing the machine. The main difference is achieved by the software solutions, they believe. "If you can do hundreds of coating experiments per day, you need to have the right tools at hand to extract all the knowledge", commented Mr. Zech. That’s why hte is also developing the corresponding data management solutions. The scientist can design hundreds of complex coating recipes easily in a web-based design software, and then execute them automatically on the platform in an unattended fashion. The acquired processing data is automatically written back to the database and integrated with results from coating analysis and performance testing. Therefore, the scientist achieves a huge productivity gain yielding faster product and process development and much better process understanding.
For more information, please contact Torsten Zech of hte at email@example.com or visit www.hte-company.de/.