Removal of fine powders from film surface. II. Effect of operating parameters on the removal efficiency.

In the previous paper, a novel fine particle removal system composed of a corona-discharge neutralizer, a pulse-jet air unit and an image processing system has been developed and applied to the removal of fine particles from film surface. We have calculated the van der Waals and electrostatic forces between particle and film and then reported that the electrostatic force influenced the adhesion characteristics significantly and thus the elimination of electrostatic charge should be necessary for the effective removal of fine particles. In this paper, we have modified the corona-discharge neutralizer for getting much better removal performance. The effect of operating parameters on the removal efficiency was investigated experimentally. The ratio of fine particle remained on the film surface after removal experiment as a function of particle size was measured. It was found that fine particles smaller than 15 microm, which were impossible to remove by other conventional techniques, could be almost completely removed. This method is anticipated to be used in the capsule filling, film packaging and tabletting processes for prevention of stain on lens of video automatic inspection machines, unpredictable movement of electronic devices, and deteriorates of product quality.