System for spray coating substrates

A system for spray coating of containers with a liquid coating material comprising containing particles of a film-forming material in a liquid vehicle, said system comprising, in combination,

• an enclosed coater including a coating chamber for continuously receiving a series of containers to be coated, said containers moving vertically downward into said coating chamber to be coated and vertically upwardly out of the coating chamber after spray coating,
• spray nozzle means in a vertical wall of said chamber for dispensing a stream of said liquid coating material,
• means for locating said containers to be coated in proximity to said spray nozzle means such that on actuation of said spray nozzle means said stream of liquid coating material impacts on the surface of the containers to be coated,
• oven means spaced from said continuous coater for receiving said containers having the liquid coating material thereon, said oven means including heating means for heating the coating material on the substrate to remove said liquid vehicle to form a substantially tack-free film of said material on said substrate,
• conveyor means for continuously transporting said containers into said coater, into proximity to said spray nozzle means for impact spray coating of said containers, vertically upwardly out of said continuous coater, to said oven means, and into and out of said oven means, the length of travel of said coated containers through said oven means being such in relation to the speed of said conveyor means that said liquid coating on said containers is dried to a substantially tack-free condition without distortion of the containers,
• means for rotating said containers as they pass into proximity of said spray nozzle means, as they travel from said continuous coater to said oven means, and while in said oven means,
• overspray control means for containing and conveying the airborne overspray from said coating chamber, said overspray control means comprising a particle collector for collecting the particles of film-forming material in the airborne overspray, means for drawing the airborne overspray from said chamber to said collector and duct means connecting said particle collector to said coating chamber for containing said overspray as it moves from said chamber to said collector, said particle collector being mounted above the top of the coater, said duct means including a mask having inlet and outlet openings in the shape of the silhouette of the containers being coated permitting the containers to pass therethrough and into said duct means and then to enter and exit the top of the coating chamber, said means for drawing the airborne overspray from said chamber to said particle collector being operative to draw ambient air through said openings in said mask to cause drying of said overspray in said duct means between said coating chamber and said particle collector, said particle collector being removed from said coating chamber a sufficient distance such that said particles of film-forming material are substantially dry on reaching said collector,
• a second mask over the top of the coating chamber having inlet and outlet openings in the shape of the silhouette of the containers to be coated permitting their entrance to and exit from the coating chamber while limiting escape of the airborne overspray through the top of the chamber, and
• liquid spray material supply means comprising valves and conduits defining two alternate flow paths from a source of liquid coating material to said spray nozzle means, said valves and conduits being operative to alternate flow of liquid coating material through either flow path while permitting reverse flushing of the other flow path.