METHOD FOR UNIFORMLY DISTRIBUTING DISCRETE PARTICLES ON A MOVING POROUS WEB

摘要

METHOD FOR UNIFORMLY DISTRIBUTING DISCRETE PARTICLES ON A MOVING POROUS WEB The present invention comprises method and apparatus for substantially uniformly distributing a layer of discrete particles along a predetermined portion of the uppermost surface of a moving porous web so that the particles occupy less than 100% of the predetermined portion of the uppermost surface of said moving web. The method preferably comprises the steps of (a) entraining the particles into a moving gaseous stream; (b) passing the gaseous stream through a conduit having a discharge end with a nozzle exit positioned adjacent the uppermost surface and oriented so as to discharge the gaseous stream containing said entrained particles in a direction substantially parallel to the direction of travel of the moving porous web; (c) mixing the particles entrained in the gaseous stream inside the conduit to provide a substantially uniform distribution of the particles, as measured across the width of the nozzle exit of said conduit In a direction perpendicular to the direction of travel of said moving porous web; (d) discharging the gaseous stream containing the uniformly distributed entrained particles from the conduit adjacent the predetermined portion of the uppermost surface of the moving porous web; and (e) maintaining the fluid pressure adjacent the lowermost surface of the moving porous web at a level lower than that adjacent the uppermost surface of the web in an area coinciding in width to the predetermined portion of the web, said area being located near the nozzle exit of the conduit, whereby the bulk of the uniformly distributed particles entrained in the discharged gaseous stream are substantially uniformly deposited onto the predetermined portion of the uppermost surface of the moving porous web as the bulk of the gas in the gaseous stream is drawn from the uppermost to the lowermost surface of said porous web.