US 4,027,366 A · Multilayer coated substrate

Abstract

A process for electrostatically applying a multilayered coating on a substrate in one operation or step is disclosed, wherein a mixture of powders of at least two different coating materials is used as the coating composition, each powder, in the case of non-conducting powders, differing from the others in dielectric constant by a factor of at least 0.1, and the powders being of substantially different specific gravities, with the components having the lowest dielectric constant value having the lowest specific gravity value. At least one of the powders will be a powder of a film-forming non-conductive organic or inorganic polymer. Upon electrostatically applying a coating of this powdered composition to a conductive substrate which has a neutral charge or a charge opposite from that of the coating composition powder particles, the powders stratify into distinct layers of different compositions. The powders adhere to the substrate because of contact or static electrification for a reasonable length of time and until at least one of the powders can be cured or fused to form the final coating. Thus, for instance, in only one pass with an electrostatic spray gun, a protective coating of superimposed layers of zinc, epoxy, and polyethylene can be applied to a conductive substrate.

Claims10

Dependent claims

An article of manufacture consisting essentially of a conductive substrate and, adjacent and overlying said conductive substrate, a coating comprising a plurality of superimposed, distinct layers,

the layer next to the conductive substrate consisting essentially of a layer of conductive metal selected from the group consisting of iron, stainless steel, zinc, copper, nickel, tin, chromium, brass, titanium, zirconium, lead and alloys of these metals,
at least one of said layers consisting essentially of at least one first film-forming non-conductive organic or inorganic polymer,
the specific gravity of said conductive metal being at least three times that of said first polymer,
said coating being applied to said conductive substrate in one step by electrostatically applying an admixture of powders, said admixture including powders having average particle sizes less than 50 microns of said conductive metal and powders having average particle sizes of about 10 to 300 microns of said first polymer, whereby said powders stratify into distinct, overlying layers, and thereafter curing or fusing at least one of said powders,
whereby the superimposed layers of the coating exhibit improved adhesion as compared to similar articles wherein the coating layers are separately applied and cured or fused.

2 more elements

Dependencies are inferred from the claim text.

Multilayer coated substrate

Life of this patent

Multilayer coated substrate

Life of this patent

Abstract

Claims10