Inkjet system for printing mechanical reinforcing patterns directly on fragile membranes floating on liquid surfaces

Ultrathin porous membranes can be employed for applications in the field of micro- and ultrafiltration and offer a low flow resistance. However, due to their thickness below 1 m they are very fragile. Therefore, we recently reported on a process to increase the mechanical stability by inkjet printing of UV curable inks to create reinforcing patterns on top of these membranes [1]. Based on this laboratory approach we realized now a specific inkjet printing system to apply the process efficiently on larger areas. The membranes are first manufactured on a water surface in a Langmuir trough [2]. Therefore, the inkjet system realized here is composed of a 3D motion system for a multi-nozzle printhead and a UVLED-lamp. In order to prevent waves leading to undefined displacements of the floating membranes the filled trough is stationary while the printhead and the UVLED-lamp are moved. The positioning stages have a high accuracy and enable a precise movement of the printing an d UV curing device relative to the membranes. Deviating from previous procedures that needed intermittent support of the porous membrane by a solid support, the reinforcing patterns now are created directly on top of the floating membranes. Deposition is done by multiple motion procedures combined with triggered printing and UV curing events. The patterns can be deposited in several minutes with resolutions of up to 800 dpi covering an area of about 130 cm2. While the porous membranes before application of reinforcement pattern are very fragile, the reinforced porous membranes are stable enough to be lifted off the water surface and handled manually without special precautions. ©2012 Society for Imaging Science and Technology