10.8(b)), a liquid film is formed on the applicator roller rotating through the coating liquid, metered by a metering roller, and deposited on the substrate fabric on a back-up roller. In three-roll pan feed or L-head coating ( Fig. It can be problematic when coating liquid has low viscosity.
This configuration needs only a minimal amount of coating fluid, but a drawback is possible coating fluid leakage. Film formed on the applicator roller is deposited onto the substrate surface supported by a back-up roller. After coating liquid transfers from the metering roller to the applicator roller, any coating liquid remaining on the metering roller surface is cleaned by a doctor blade, otherwise it will result in coating defects, such as streaks or film roughness. The applicator roller picks up the coating liquid from the nip and the amount of coating liquid delivered to the fabric substrate is metered by the metering roller rotating in a reverse direction to the applicator roller.
10.8(a)), the nip formed by a metering roller and an applicator roller is flooded with coating liquid and functions as a reservoir ( Greer, 1995 Grant, 1978). Common three-roll configurations are nip feed coating and L-head coating. Three-roll coating uses a metering roller, an applicator roller and a backup roller.
