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US 5,178,736 AGranted
Light colored conductive electrocoat paint
AssigneeE. I. Du Pont de Nemours and Company
InventorEugene Richardson
Life of this patent
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Abstract
Disclosed herein are cathodic electrocoat compositions which contain electroconductive pigments. These pigments are light in color, and can be added at higher pigment to binder ratios for improved edge coverage. More specifically, the electroconductive pigments are a two-dimensional network of antimony-containing tin oxide crystallites which exist in a unique association with amorphous silica or with a silica-containing material.
Claims7
In an improved method of cathodic electrocoating comprising the following steps:
- a) cathodically electrocoating a first cathodic electrocoat composition having a film forming polymer binder of a crosslinkable resin and a crosslinker on a metal substrate;
- b) baking the cathodically electrocoated metal substrate to cure the film forming polymer;
- and
- c) re-electrocoating a second cathodic electrocoat composition over the substrate with the cured film;
- wherein the improvement comprises the first cathodic electrocoat composition that contains an electroconductive pigment in a pigment to binder weight ratio of about 0.1:1 to 0.5:1 in which the electroconductive pigment is a powder comprising shaped particles selected from the group consisting of amorphous silica, silica containing material or particles comprising an inert core material having an amorphous silica coating or a silica containing coating;
- said shaped particles being surface-coated with a two-dimensional conducting network of antimony-containing tin oxide crystallites in which the antimony content ranges from about 1-30% by weight of the tin oxide crystallites.
3 more elements
Dependencies are inferred from the claim text.