Spray nozzle for applying metal-filled solventless resin coating and method

A spray coating apparatus, comprising

• a spray gun having
• i. a spray nozzle for directing liquid resin toward a substrate intended to be coated, said nozzle having a central orifice and an atomizing orifice surrounding said central orifice,
• ii. a conduit for introducing liquid resin to said nozzle,
• iii. said spray nozzle having a cylindrically shaped body and being closed at one end, said conduit for leading the liquid resin into a central orifice formed in said one end for injecting liquid resin, said housing having passage for leading air into an orifice surrounding said central orifice for injecting a stream of atomizing air downstream of said orifice and defining with said liquid resin a convergent stream of atomized liquid resin for defining a plume having a low pressure section,
• iv. a pair of diametrically opposed passages in said housing and leading metallic powder into discharge outlets formed in said one end on opposite sides of said central orifice for directing said metallic powder into the low pressure section of said plume prior to being impinged on said substrate,
• vi. a source of liquid spray connected to said conduit and a source of metallic powder connected to each of said diametrically opposed passages, and
• vii. air pressure for transporting said metallic powder to said discharge outlets whereby the metallic powder mixes with said atomized liquid resin downstream of said central nozzle and in said plume prior to being applied to said substrate.

A system for applying a coating to a substrate including metallic powder comprising,

• a spray gun having
• i. an elongated body closed at one end, a conduit for leading liquid resin to a central orifice at said one end and a passage in said body for leading air into an annular discharge port surrounding said central orifice for atomizing said liquid resin and forming a convergent spray defining a plume with a low pressure section,
• ii. diametrically opposed passages for leading the metallic powder to diametrically opposed discharge ports for admitting metallic powder into the low pressure section of said plume,
• means for measuring the amount of liquid resin and the amount of metallic powder to define a given ratio of the two mediums,
• transporting means for conducting the liquid resin to said conduit and for conducting said metallic powder to said spray nozzle in the desired proportions,
• a process control/computer system for controlling the proper ratio of the two mediums, and
• said transporting means includes a pair of air eductors for leading metallic powder into said diametrically disposed passages whereby the metallic powder mixes with said atomized liquid resin in said plume before being applied to said substrate.