Oct 8 2009
A complete slot die coating station with all components from idler roll to backing roll is now available for renting by manufacturers in Asia, enabling them to eliminate hours of setup in switching from roll to slot die coating as they carry out product and process development with slot dies in their own plants, it was announced by Extrusion Dies Industries, LLC (EDI) at CPP Expo (Booth 5549).
Called the Modular Coating System (MCS), the coating station is built by EDI in the U.S.A. and has been available only in North America. Recently, however, EDI shipped an MCS unit to its subsidiary EDI Precision Dies (Shanghai) Co., Ltd. (EDI China), and it has already been employed by China-based manufacturers of lithium-ion batteries.
The MCS rolls into place on nearly any commercial coating line, enabling operators of coating systems to switch readily from and back to conventional processes like roll coating. Included in the system are an Ultracoat adjustable-lip slot die coating head, a fluid-delivery system, an adjustable support for positioning the die lip with respect to the web, idler rolls, and a precision backing roll. These components are unitized within a steel frame whose crossbars maintain straightness during operation and adjustment. The coating station is mounted on casters.
"With a standard slot die coating system assembled from individual components, it can take up to half a day, and even more for really large dies, to set up the system so that it is vertically plumb, the rolls are level with respect to one another, and the die is properly positioned with respect to the backing roll," said Jason Q.Yin, general manager of EDI China. "EDI's MCS eliminates much of this time, along with the risk of damaging rolls during handling."
Ultracoat dies have a flexible lip, whose adjustability is the key to controlling the lip gap
profile and thus the coat weight. This is an important advantage in applying slurries such as those
used for coating flexible battery or photovoltaic components, since slurry viscosity changes over the course of a production run and the die needs to be adjusted accordingly.
Many coating line operators run several roll coating processes, noted Mr. Yin. "In roll coating, the amount of material deposited on the substrate is controlled indirectly by means of wiping blades or pre-set gaps between rollers; any excess coating material is scraped away and returned to the coating bath; and the bath itself is open to the workplace environment. Slot dies, on the other hand, are closed systems, and the amount of coating material is pre-metered by means of a precision pump. As a result, slot die coating provides these advantages: 1) more consistent coat weight and cross-web distribution; 2) higher line speeds; and 3) minimization of volatile emissions, coating contamination, raw material waste, and workplace messiness."