Patent ID: 7217444
Filing Date: 2007-05-15
Classification: B05B,B05D

Abstract:
1. A process for electrostatic powder coating of an article, comprising the steps of: triboelectrically charging powder particles contained in a chamber, said powder particles having an average diameter of about 10 μm combining said triboelectrically charged powder particles with magnetic beads in said chamber, said charged powder particles being electrostatically attracted to said magnetic beads; providing a magnetic brush roll; advancing said combined magnetic beads and charged powder particles attracted thereto by said magnetic brush roll from said chamber to a loading nip formed between said magnetic brush roll and at least one rotatable donor roll; metering said combined magnetic beads and charged powder particles being advanced by said magnetic brush roll to provide a uniform layer thereon; rotating said at least one donor roll past said loading nip and a location for detaching said charged powder particles therefrom; extracting said charged powder particles from said magnetic beads on said magnetic brush roll at said loading nip and depositing said charged powder particles onto said at least one donor roll; detaching said charged powder particles from the at least one donor roll by a plurality of wires having an AC bias applied thereto, said wires being adjacent said at least one donor roll at said location for detaching said charged powder particles, said charged powder particles detached from said at least one donor roll by said AC biased wires forming a powder cloud in the vicinity of said AC biased wires; directing said cloud of charged powder particles toward an article to be coated by an air jet; and grounding said article, so that said charged powder particles are attracted to and coat said article.