System for electrocoating conductive substrates

Abstract

The present invention is directed towards an electrocoating system comprising a tank comprising at least one sidewall and configured to hold an electrodepositable coating composition for receiving a substrate to be coated, and a movable electrode positioned within the tank, wherein the movable electrode does not extend through the sidewall. Also disclosed herein are methods of coating substrates, systems for coating a substrate, and coated substrates.

What is claimed is: 
     
         1 . An electrocoating system comprising:
 a tank comprising at least one sidewall and configured to hold an electrodepositable coating composition for receiving a substrate to be coated, and   a movable electrode positioned within the tank, wherein the movable electrode does not extend through the sidewall.   
     
     
         2 . The electrocoating system of  claim 1 , further comprising at least one means for positioning the movable electrode within the tank. 
     
     
         3 . The electrocoating system of  claim 1 , wherein the movable electrode comprises an expandable electrode. 
     
     
         4 . The electrocoating system of  claim 3 , wherein the expandable electrode is positioned on the sidewall and is configured to expand away from the sidewall. 
     
     
         5 . The electrocoating system of  claim 3 , wherein the tank further comprises a floor and the expandable electrode is positioned on the floor, wherein the expandable electrode is configured to expand away from the floor and does not extend through the floor of the tank. 
     
     
         6 . The electrocoating system of  claim 3 , further comprising at least one means for expanding and/or means for retracting the expandable electrode within the tank. 
     
     
         7 . The electrocoating system of  claim 6 , wherein the means for expanding and/or means for retracting the expandable electrode within the tank comprise an apparatus positioned above the tank, the apparatus having an arm configured to position the expandable electrode within the tank. 
     
     
         8 . The electrocoating system of  claim 7 , wherein the apparatus comprises a cart, wherein the cart is positioned on at least one rail and is laterally moveable on the rail relative to the tank. 
     
     
         9 . The electrocoating system of  claim 8 , wherein the electrocoating system further comprises a second cart comprising an arm connected to the expandable electrode, wherein the first and second carts are configured to at least partially expand the expandable electrode. 
     
     
         10 . The electrocoating system of  claim 9 , wherein the system further comprises a means for further expanding the expandable electrode. 
     
     
         11 . The electrocoating system of  claim 6 , wherein the means for expanding and/or means for retracting the expandable electrode comprises a driving means, wherein the driving means comprises a rack and pinion, a pneumatic press, a hydraulic press, or a combination thereof. 
     
     
         12 . The electrocoating system of  claim 3 , wherein the expandable electrode comprises a telescoping electrode. 
     
     
         13 . The electrocoating system of  claim 12 , wherein at least a portion of the telescoping electrode is formed of telescoping sections that may be nested one within another, wherein the telescoping electrode comprises n telescoping sections each having a length of X, the telescoping sections allow expanding the length of the telescoping electrode by a length of up to nX−X, wherein n is an integer >1. 
     
     
         14 . The electrocoating system of  claim 3 , wherein the expandable electrode comprises a flexible material comprising a rope or hose-like configuration. 
     
     
         15 . The electrocoating system of  claim 1 , further comprising a means for counter-balancing the movable electrode. 
     
     
         16 . The electrocoating system of  claim 1 , further comprising at least one stationary electrode. 
     
     
         17 . The electrocoating system of  claim 3 , wherein the expandable electrode further comprises a spacer. 
     
     
         18 . The electrocoating system of  claim 1 , wherein the movable electrode is located entirely within the tank. 
     
     
         19 . The electrocoating system of  claim 1 , wherein the movable electrode is completely submerged in the electrodepositable coating composition. 
     
     
         20 . The electrocoating system of  claim 1 , wherein the movable electrode has a cross-sectional shape of a triangle, a square, a rectangle, a pentagon, a hexagon, a heptagon, an octagon, a flat plate, a C-shape, a fanned shape, or an annular shape. 
     
     
         21 . The electrocoating system of  claim 1 , wherein the movable electrode is connected to a terminal of a power supply and the substrate to be coated is connected to a terminal of opposite polarity of the power supply. 
     
     
         22 . A method for coating a substrate using the electrocoating system of  claim 1 , the method comprising:
 positioning the substrate within the tank wherein a surface of the substrate to be coated is submerged in the electrodepositable coating composition held in the tank;   positioning the movable electrode;   electrically coupling the movable electrode and the substrate to opposite poles of a power source; and then   applying an electrical current from the power source to electrodeposit the electrodepositable coating composition onto the surface of the substrate.   
     
     
         23 . The method of  claim 22 , wherein the substrate comprises a container having a cavity, and the movable electrode is positioned in the cavity. 
     
     
         24 . The method of  claim 22 , wherein the movable electrode has an external surface, and the external surface is at a distance of less than or equal to four feet from the surface of the substrate to be coated after the positioning of the movable electrode. 
     
     
         25 . The method of  claim 22 , further comprising at least one of:
 pretreating the substrate prior to processing the substrate in the electrocoating system;   priming the substrate prior to processing the substrate in the electrocoating system; and/or   applying a topcoat coating to the substrate after processing the substrate in the electrocoating system.   
     
     
         26 . A substrate coated by the method of  claim 22 . 
     
     
         27 . A system for coating a substrate comprising the electrocoating system of  claim 1  and further comprising at least one of:
 a pretreatment system for pretreating the substrate prior to processing the substrate in the electrocoating system; 
 a priming system for priming the substrate prior to processing the substrate in the electrocoating system; and/or 
 a topcoat system for applying a topcoat coating to the substrate after processing the substrate in the electrocoating system.