Internal mix plural component system

Abstract

An internal mix, air-assisted, airless atomization, plural component spraying system includes a source of resin; a source of catalyst for the resin; a spray gun to mix the resin and catalyst and direct the mixture as a spray to a substrate; and a source of compressed air to assist in atomization of the mixed resin and catalyst. The spray gun includes a mixing apparatus and an atomizer including a liquid nozzle for forming the mixed resin and catalyst into a fan-like film with expanding edges extending from a liquid orifice, and an air nozzle for forcing a flow of compressed air to converge at an elongated air orifice and expand in a fan-like flow. The mixing apparatus includes a first internal passageway for receiving a flow of resin having a portion of restricted diameter opening into an expanding passageway portion and one or more radial second passageways opening into the restricted diameter portion for delivering catalyst into the first passageway so that the resin and catalyst are thoroughly mixed by a venturi effect at substantially lower pressures than in prior systems. The compressed air flow is juxtaposed to and interacts with the fan-like film of mixed resin and catalyst to assist in atomization and provide atomized particles of uniform, small size and to further mix the mixed catalyst and resin particles.