US20220090288A1

US20220090288A1 - System for electrocoating conductive substrates

Info

Publication number: US20220090288A1
Application number: US17/424,643
Authority: US
Inventors: Brent A. Schwartz; Tammy L. Hutchinson; Tod M. Hough; Dennis J. Siefer; Judith A. Bethoski; Mark L. Follet; Irina G. Schwendeman; Amy E. Harrison
Original assignee: PPG Industries Ohio Inc
Current assignee: PPG Industries Ohio Inc
Priority date: 2019-01-23
Filing date: 2020-01-22
Publication date: 2022-03-24
Also published as: MX2021008869A; CN113348272A; KR20210114043A; BR112021014425A2; WO2020154430A1; EP3914756A1

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.

Description

FIELD OF THE INVENTION

The present invention relates to electrocoating systems for electrocoating a substrate. The present invention also relates to a system for coating substrates, methods for coating substrates, and coated substrates.

BACKGROUND INFORMATION

Electrodeposition as a coating application method involves the deposition of a film-forming composition onto a conductive substrate under the influence of an applied electrical potential. Electrodeposition has gained popularity in the coatings industry because it provides higher paint utilization, outstanding corrosion resistance, and low environmental contamination as compared with non-electrophoretic coating methods. However, some conductive substrates are more difficult to coat by electrodeposition because of a number of factors, including the shape and size of the substrate. For example, it may be difficult to coat both the internal and external surfaces of substrates having an open-pocket shape, such as a container or a pipe, using conventional electrocoat systems. Therefore, an electrocoating system that is capable of coating a wide range of substrates is desired.

SUMMARY OF THE INVENTION

Disclosed herein is 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 is a method for coating a substrate comprising electrophoretically applying an electrodepositable coating composition to at least a portion of the substrate using the electrocoating system of the present invention. This method comprises 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.
Further disclosed herein are substrates coated by the method of the present invention.
Still further disclosed herein is a system for coating a substrate comprising the electrocoating system of the present invention, and further comprising at least one of: a pretreatment system for pretreating the substrate prior to processing the substrate in the electrocoating system; a primer system for applying a primer to 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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B is a top view of an exemplary electrocoating system of the present invention with a movable electrode in a first position in FIG. 1A and the movable electrode in a second position in FIG. 1B. FIGS. 1C and 1D is a side view of an exemplary electrocoating system of the present invention with a movable electrode in a first position in FIG. 1C and the movable electrode in a second position in FIG. 1D.

FIG. 2A is an illustration of an exemplary electrocoating system of the present invention with an expandable electrode in a first state in a tank with a substrate to be coated. FIG. 2B is an illustration of the exemplary electrocoating system of FIG. 2A with the expandable electrode in an expanded state.

FIG. 3A is a perspective view of an exemplary electrocoating system of the present invention with an expandable electrode in a first state present in a tank. FIG. 3A further shows a first apparatus having an arm connected to the expandable electrode and two legs positioned along a set of rails running along both sides of the bottom of the tank, and a second apparatus also having a second arm connected to another section of the expandable electrode and two legs positioned along a second set of rails running along both sides of the bottom of the tank. FIG. 3B is a top view of the exemplary electrocoating system shown in FIG. 3A, and FIG. 3C is a sideview of the exemplary electrocoating system shown in FIG. 3A.

FIG. 4A is a perspective view of an exemplary electrocoating system of the present invention with the expandable electrode in a partially expanded state. FIG. 4B is a top view of the exemplary electrocoating system shown in FIG. 4A, and FIG. 4C is a side view of the exemplary electrocoating system shown in FIG. 4A.

FIG. 5A is a perspective view of an exemplary electrocoating system of the present invention with the expandable electrode in a fully expanded state. FIG. 5B is a top view of the exemplary electrocoating system shown in FIG. 5A, and FIG. 5C is a side view of the exemplary electrocoating system shown in FIG. 5A.

FIG. 6A is a perspective view of an exemplary electrocoating system of the present invention with an expandable electrode wrapped completely around a reel, and a substrate present in the tank. FIG. 6B is a perspective view showing the expandable electrode partially inserted through the substrate, with the dotted line indicating the expandable electrode is inside the substrate. FIG. 6C is a perspective view showing the expandable electrode fully expanded through the substrate and secured to a sidewall using an anchor, with the dotted line indicating the expandable electrode is inside the substrate.

FIG. 6D is a perspective view of an exemplary expandable electrode having a spacer. FIG. 5E is an inline view of the exemplary expandable electrode having a spacer.

FIG. 6F is a perspective view of an exemplary electrocoating system of the present invention with an expandable electrode having a spacer positioned within a substrate present in the tank.

FIG. 7A is an illustration of an exemplary electrocoating system of the present invention with an expandable electrode positioned on the floor of a tank in a first state with a substrate to be coated. FIG. 7B is an illustration of the exemplary electrocoating system of FIG. 7A with the expandable electrode in a partially expanded state. FIG. 7C is an illustration of the exemplary electrocoating system of FIG. 7A with the expandable electrode in a fully expanded state.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to an electrocoating system for electrocoating a substrate. The present specification also discloses systems for coating a substrate, methods for coating substrates, substrates coated in accordance with one or more of the methods described herein, and/or through the use of one or more of the systems described herein.

Electrocoating System

As shown for illustration purposes in FIGS. 1A and 1B, the present invention is directed to an electrocoating system 10 comprising a tank 100 comprising at least one sidewall 120 and configured to hold an electrodepositable coating composition 900 for receiving a substrate 1000 to be coated, and a movable electrode 200 positioned within the tank 100, wherein the movable electrode 200 does not extend through the sidewall 120. As used herein, the term “movable electrode” refers to an electrode that is configured to change its position and/or orientation in the tank. The movement may be actual movement of the movable electrode 200 or by a change in the configuration of the movable electrode 200. For example, the movable electrode 200 may comprise an expandable electrode 200, as discussed in more detail below. Alternatively, the movable electrode 200 may comprise a means for positioning 300 the movable electrode in the tank, and the means for positioning 300 may allow for the movement of the movable electrode.
According to the present invention, and as shown in the Figures, the tank 100 is configured to hold an electrodepositable coating composition 900. The tank 100 may comprise any material known in the art. For example, the tank 100 may comprise plastic, metal having an insulating liner such as metal having an internal plastic or fiberglass liner, or metal having an insulating coating. The tank 100 may comprise any geometric shape. For example, the tank 100 may be generally rectangular or generally round or spherical. The tank 100 may comprise a floor 110 and at least one sidewall 120, such as four sidewalls as in case of the depicted exemplary rectangular configuration, extending up from the floor 110 to form a cavity within which the electrodepositable coating composition 900 may be held.
The movable electrode 200 may comprise any suitable conductive material known in the art, and the movable electrode 200 may comprise both conductive and non-conductive materials. For example, the movable electrode 200 may comprise any other materials that may comprise the substrate, as described herein, as well as ruthenium oxide. The movable electrode 200 may optionally comprise or be made of a non-porous material. As used herein, the term “non-porous” generally refers to materials that are not permeable to fluids such as water or air.
The movable electrode 200 may have any cross-sectional shape. For example, the movable electrode 200 may have the shape of any polygon, such as a triangle, square, rectangle, pentagon, and the like, a flat plate, a C-shape, a fanned shape, annular shape, as well as a generally round shape, such as tubular movable electrodes having a circular or oval cross-sectional shape. The cross-sectional shape of the movable electrode 200 may be selected based upon a number of factors, such as, for example, the surface area of the substrate 1000 to be electrocoated, the relative surface area of the movable electrode 200 relative to the surface area of the substrate 1000 to be coated, the distance between the movable electrode 200 and substrate 1000 during electrocoating, and the shape of the substrate 1000.
The cross-sectional area of the movable electrode 200 is not particularly limited and may depend upon and/or be proportional to the size of the substrate 1000 to be coated. For example, substrate having large cross-sectional areas may require a movable electrode 200 having a larger cross-sectional area. In addition, the cross-sectional shape of the movable electrode 200 may be selected based upon the shape of the substrate 1000 to be coated. For example, a movable electrode 200 may have a cross-sectional shape that mirrors the cross-sectional shape of the substrate 1000 to be coated. In addition, the cross-sectional area of the movable electrode 200 may be such that the external surface of the movable electrode 200 is within four feet of the surface of the substrate 1000 to be coated. For example, an exemplary movable electrode 200 having a square cross-sectional shape and a cross-sectional area of at least 19.01 ft²(1.77 m²) may be used to coat an exemplary substrate 1000 having a square cross-sectional shape and a cross-sectional area of 100 ft²(9.29 m²).
The leading (or terminal) edge of the movable electrode 200 may optionally comprise one or more protrusions that extend from the leading edge of the movable electrode 200. The protrusions may extend into harder to reach portions of the substrate 1000 to be coated, such as complex geometries or the corners of a square or rectangular shaped substrate 1000. This may improve the charge density of the electrodepositable coating composition 900 in such corners and improve the deposition of the electrodepositable coating composition 900 in such corners.
The movable electrode 200 may be configured to be free of contact points with the substrate 1000 to be coated. As used herein, the term “contact point” with reference to the movable electrode 200 and substrate 1000 refers to physical contact between the movable electrode 200 and substrate 1000 such that there is a void present between the substrate 1000 and the movable electrode 200 that may be filled with the electrodepositable coating composition 900. The term “contact point” explicitly excludes electrical communication between the components.
The movable electrode 200 may be positioned in the tank 100 such that the entire movable electrode 200 is submerged in an electrodepositable coating composition 900 when the tank 100 is at least partially filled. The movable electrode 200 may be configured such that the movable electrode 200 does not extend through the floor 110 or a sidewall 120 of the tank 100. As used herein, the term “through” with respect to the floor 100 or sidewall 120 of the tank 100 means that the movable electrode 200 does not extend through any opening located in the floor 110 or sidewall 120 of the tank 100 such that a portion of the movable electrode 200 is positioned outside of the tank 100.
The movable electrode 200 comprises a surface and the surface may be essentially free of electrocatalyst. As used herein, the term “electrocatalyst” refers to those used in electrochemical ozone generating systems, such as, for example, lead dioxide.
As shown in FIGS. 1 and 2, the means for positioning 300 the movable electrode 200 within the tank 100 may comprise one or more apparatus(es) 310 positioned outside of the tank 100, and the apparatus(es) 310 may comprise an arm connected to the movable electrode 200 and configured to position the movable electrode 200 within the tank 100. The apparatus 310 may have any configuration and be positioned anywhere outside the tank 100 as long as the arm is configured to extend into the tank 100 to position the movable electrode 200. For example, as shown in FIGS. 1A and 1B, the apparatus 310 may comprise a cart 330, and the cart 330 may be positioned on at least one rail 350 such that the cart is laterally moveable on the rail 350 relative to the tank 100. The rail 350 may be positioned above, beside or under the tank 100. For example, in FIGS. 1A and 1B, two rails 350 are positioned on the top of opposite sidewalls 120 of the tank 100 with each rail (350 and 370) supporting a cart 330 that is connected to either side of the apparatus 310. The means for positioning 300 the movable electrode 200 in FIGS. 1A and 1B move the movable electrode 200 from a first position (FIG. 1A) to a second position (FIG. 1B) by moving the carts 330 along the rails 350. The means for positioning 300 may comprise any means known in the art, such as, for example, a rack and pinion, a pneumatic press, a hydraulic press, a chain and the like, or a combination thereof. The means for positioning 300 the movable electrode 200 may further comprise a means for moving the movable electrode in a vertical direction relative to the tank (not shown). The means for moving in a vertical direction may comprise any means known in the art, such as, for example, a rack and pinion, a pneumatic press, a hydraulic press, a chain and the like, or a combination thereof.
The electrocoating system 10 may comprise a means for positioning and/or rotating the substrate 1000 (not shown). The means for positioning and/or rotating the substrate 1000 allow for the substrate 1000 to be positioned into the tank 100. The means for positioning and/or rotating the substrate 1000 may further allow for the substrate 1000 to be tipped and/or rotated along its length in order to allow any air trapped in the substrate 1000 to escape such that all or substantially all of the surface of the substrate 1000 is in contact with the electrodepositable coating composition 900 contained within the tank 100. The tipping may be, for example, about 5° relative to the main axis along the length of the substrate 1000, and may be rotated, for example, about 15° around the main axis along the length of the substrate 1000. The tipping and/or rotating of the substrate 1000 may occur before operation of the electrocoating system 10 or during operation of the electrocoating system 10. In addition, the movable electrode 200 may be configured to mirror the rotation of the substrate 1000 during operation of the electrocoating system 10 to ensure that the movable electrode 200 maintains constant distance from the surface of the substrate 1000 during operation.
The means for positioning and/or rotating the substrate 1000 may comprise a Roll Over Dip (or RoDip) system wherein the substrate 1000 is positioned on a conveyer above the tank 100, and the conveyer rotates the substrate 1000 and allows it to be dipped (i.e., submerged) into the electrodepositable coating composition 900 held within the tank 100 of the electrocoating system 10. The movable electrode 200 may be moved into position while the conveyer is rotating the substrate 1000, and the electrocoating system 10 may optionally be operated with the substrate 1000 being rotated by the RoDip system, and the movable electrode 200 may also optionally be rotated.
As discussed above, the movable electrode 200 may comprise an expandable electrode 200. As shown for illustration purposes in FIGS. 2A and 2B, the present invention is directed to an electrocoating system 10 comprising a tank 100 configured to hold an electrodepositable coating composition 900 for receiving a substrate 1000 to be coated, and an expandable electrode 200 positioned within the tank 100. The expandable electrode 200 is configured to expand from a first state (FIG. 2A) to an expanded state (FIG. 2B).
According to the present invention, and as shown in FIGS. 2A and 2B, the electrocoating system 10 further comprises an expandable electrode 200 positioned within the tank 100. The expandable electrode 200 may be configured to be expanded from a first state, as shown in FIG. 2A, to an expanded state, as shown in FIG. 2B. As used herein, the term “expandable electrode” refers to an electrode having a dimension that can non-destructively be increased in at least one spatial direction. As used herein, the terms “expand”, “expanding”, “expandable” and the like refer to an increase in the dimension of a body in at least one spatial direction, and includes bodies that increase their length through a change in structure (e.g., a telescoping mechanism or an unwinding mechanism). The term “expandable electrode” does not include unitary materials that may expand due to the application of an external energy force, such as, e.g., a metal expanding due to the application of heat. The expandable electrode configuration is not limited as long as the expandable electrode is configured to expand in length. A portion or substantially all of the expandable electrode 200 may comprise a material that expands by a change in the configuration of the material, such as, for example, a telescoping section, an accordion-like section, a spring-shaped section, and the like. Alternatively, the expandable electrode 200 may comprise a flexible material capable of having its positioning expanded within the tank 100 without the length of the expandable electrode material itself changing, such as, for example, a rope or hose-like configuration that may be rolled up in a first state and unrolled in the tank 100 to expand the length of the expandable electrode 200 to an expanded state, and like structures.
The expandable electrode may also comprise combinations of the above described mechanisms, including combinations of telescoping sections, accordion-like configured sections, spring-shaped sections, and flexible materials. The expansion of the expandable electrode 200 may be along a generally linear path, such as in FIGS. 2A and 2B, but expansion along a non-linear path, as well as branching of the expandable electrode are also within the scope of the invention. For example, the expandable electrode 200 may expand in a generally linear path with multiple branches extending out from the direction of expansion of the main portion of the expandable electrode 200, such as in a generally perpendicular direction. Alternatively, the expandable electrode may branch into two or more directions, such as a fork configuration.
As shown in FIGS. 2A and 2B, the expandable electrode 200 may comprise a telescoping electrode 210. The telescoping electrode 210 may comprise telescoping sections 220 that may be nested one within another when the expandable electrode 200 is not fully expanded. The telescoping sections 220 may comprise a portion or all of the telescoping electrode 210. The telescoping sections 220 of the telescoping electrode 210 may each have a substantially uniform length of expansion, X, and the telescoping sections 220 may expand the length of the telescoping electrode 210 by up to nX−X, wherein n is an integer >1 and equal to the total number of telescoping sections 220. As used herein, the term “length of expansion” with respect to a telescoping section 220 refers to the maximum amount an additional telescoping section 220 will be able to increase the length of the telescoping electrode 210. Although the maximum expanded length of the telescoping electrode 210 is nX, the expanded length in practice may be any length greater than X to nX, depending upon the desired application and the substrate 1000 to be coated by the electrocoating system 10. The expansion of the telescoping electrode 210 may include expansion of telescoping sections 220 one at a time such that one telescoping section 220 “un-nests” at a time, the telescoping sections 220 may move all at once such that each telescoping section 220 remains partially nested at an expanded length, or a combination of the two.
The expandable electrode 200 may be fixedly positioned entirely within the tank such that the entire expandable electrode 200 is submerged in the electrodepositable coating composition 900. As used herein, an expandable electrode 200 is fixedly positioned entirely within the tank 100 when the expandable electrode 200 is secured to a portion of the tank 100 without further structures located outside the tank 100 supporting the positioning of the expandable electrode 200. For example, as shown in FIGS. 2A and 2B, the expandable electrode 200 may be fixedly positioned on a sidewall 120 of the tank 100 and may expand in a direction away from the sidewall 120. Alternatively, as shown in FIGS. 7A, 7B and 7C, the expandable electrode 200 may be positioned on the floor 110 of the tank 100 and may expand in a direction away from the floor 110. The configuration of the expandable electrode 200 may depend upon the application and the substrate 1000 to be coated by the electrocoating system 10.
According to the present invention, the electrocoating system 10 may comprise a means for positioning 300 the expandable electrode 200 within the tank 100. The means for positioning 300 the expandable electrode 200 within the tank 100 generally refers to a supporting structure connected to the expandable electrode 200 to provide support that is located at least partially outside of the tank 100. As used herein, the term “at least partially outside of the tank” with respect to a structure refers to a structure that is not submerged in the electrodepositable coating composition 900 when the tank 100 is filled to its maximum level. The means for positioning 300 the expandable electrode 200 within the tank 100 may comprise one or more apparatus(es) 310 positioned outside of the tank 100, and the apparatus(es) 310 may comprise an arm connected to the expandable electrode 200 and configured to position the expandable electrode 200 within the tank 100. The apparatus 310 may have any configuration and be positioned anywhere outside the tank 100 as long as the arm is configured to extend into the tank 100 to position the expandable electrode 200. For example, as shown in FIGS. 3A, 3B, 3C, 4A, 4B, 4C, 5A, 5B and 5C (collectively, “FIGS. 3-5”), the apparatus 310 may comprise a cart 330, and the cart 330 may be positioned on at least one rail 350 such that the cart is laterally moveable on the rail 350 relative to the tank 100. The rail 350 may be positioned above, beside or under the tank 100. For example, in FIGS. 3-5, two rails (350 and 370) are positioned on the bottom of opposite sidewalls 120 of the tank 100 with each rail (350 and 370) supporting one of the two legs 380 of one of the carts 330 and 340. The means for positioning the expandable electrode 200 within the tank 100 may also function to at least partially or fully expand the expandable electrode 200. For example, in FIGS. 3-5, a first cart 330 and a second cart 340 are configured to position the expandable electrode 200 within the tank 100. In FIGS. 3-5, the first cart 330 and second cart 340 each comprise an arm 320, with the arm 320 of the first cart 330 attached to the end of the expandable electrode 200 and the arm 320 of the second cart 340 attached to a telescoping section 220 of the expandable electrode 200. FIGS. 3A, 3B, and 3C show perspective, top and side views, respectively, of the first cart 330 and second cart 340 as positioned in a first (starting) state. FIGS. 4A, 4B, and 4C show perspective, top and side views, respectively, of the expandable electrode 200 in a partially expanded state with the second cart 340 having moved laterally away from the first cart 330 and positioning the expandable electrode 200 further in the tank 100 relative to the first state. The expansion of the expandable electrode 200 into the tank may be at least partially or fully caused by the movement of the second cart 340 if the second cart 340 causes the length of the expandable electrode 200 to increase. FIGS. 5A, 5B, and 5C show perspective, top and side views, respectively, of the first cart 330 moved laterally towards the second cart 340 to position the expandable electrode 200 in a fully expanded state further into the tank 100. The means for positioning 300 the expandable electrode 200 may further comprise a means for moving the expandable electrode in a vertical direction relative to the tank (not shown). The means for moving in a vertical direction may comprise any means known in the art, such as, for example, a rack and pinion, a pneumatic press, a hydraulic press, a chain and the like, or a combination thereof.
According to the present invention, the electrocoating system 10 may further comprise a means for expanding 400 the expandable electrode 200. The means for expanding 400 the expandable electrode 200 may comprise any suitable means known in the art. For example, as described above, the means for expanding 400 may comprise an apparatus 310 located outside of the tank 100 that moves the expandable electrode 200 into an expanded state, i.e., increases the length of the expandable electrode 200. The means for expanding 400 the expandable electrode 200 into an expanded state may alternatively comprise a driving means, and the driving means may comprise a rack and pinion, a pneumatic press, a hydraulic press, a chain and the like, or a combination thereof. Such means for expanding 400 the expandable electrode 200 may be used in combination with any appropriate configuration of the expandable electrode 200, such as a telescoping electrode, an electrode having an accordion-like configuration, and the like. The means for expanding 400 the expandable electrode 200 into an expanded state may also comprise multiple means for expanding the expandable electrode 200. For example, the means for expanding 400 the expandable electrode 200 may comprise an apparatus 310 located outside of the tank 100 that moves the expandable electrode 200 into a partially expanded state, as described above, and the electrocoating system 10 may comprise a further means for expanding 500 the expandable electrode 200 which may comprise a rack and pinion, a pneumatic press, a hydraulic press, and the like, or a combination thereof, that expands the expandable electrode 200 into a further or fully expanded state.
The means for expanding 400 the expandable electrode 200 may also comprise a means for moving a flexible material within the tank. For example, the flexible material may be connected to an extendable arm that may extend the material of the expandable electrode 200 in the tank 100. Alternatively, the flexible material may be connected to a runner that allows for the flexible material of the expandable electrode 200 to be carried into the tank 100. The flexible material of the expandable electrode 200 may be held taut in the tank 100 by any suitable means, including, for example, attachment to an anchor (not shown) present on an opposite sidewall 120 of the tank. The flexible material of the expandable electrode 200 may be especially suitable for coating long hollow substrates, such as, for example, a pipe. The flexible material of the expandable electrode 200 may be strung through the length of the pipe and secured to an anchor to hold the expandable electrode 200 in a taut generally uniform distance from the interior surface of the pipe. In such configuration, as shown in FIGS. 6A, 6B, 6C and 6F, the expandable electrode 200 may be present on a reel 210 positioned inside the tank 100, and the expandable electrode 200 may be unrolled from the reel 210 to extend through the hollow substrate 1000. An anchor 220 may be positioned on a sidewall 120 of the tank 100 to secure the expandable electrode 200 in place.
The electrocoating system 10 may further comprise a means for retracting 600 the expandable electrode 200. Any suitable means for retracting 600 the expandable electrode may be used. For example, the means for retracting 600 the expandable electrode 200 may comprise the reverse motion of the means for expanding 400 the expandable electrode 200, such as reversing the direction of force of the driving means. In another example, as shown in FIGS. 3-5, the means for retracting 600 the expanded electrode 200 may comprise a return chain 610 that applies a force to at least partially reduce expansion of the expandable electrode 200.
As mentioned above, the expandable electrode 200 may comprise a flexible material capable of having its positioning expanded within the tank 100 without the length of the expandable electrode material changing. In such configuration, as shown in FIGS. 6A, 6B, 6C and 6F, the means for retracting 600 the expandable electrode 200 may comprise a mechanism such as winding the reel 210 to retract the expandable electrode 200.
The retraction of the expandable electrode 200 may occur during electrodeposition such that the expandable electrode 200 applies a charge to and deposits the electrodepositable coating composition 900 onto a portion of the substrate 1000 as the expandable electrode 200 moves past the portion of the substrate 1000.
As shown in FIGS. 6D and 6E, the expandable electrode 200 may optionally comprise a spacer 230 positioned on the expandable electrode 200. The spacer 230 may be sized and configured in such a way that the expandable electrode 200 is maintained at a constant distance from the internal surface of the substrate 1000. For example, if the substrate 1000 is a round pipe, the spacer 230 would contact the internal surface of the substrate 1000 to maintain the expandable electrode equidistant from each portion of the cross-section of the internal surface of the substrate 1000. As shown in FIGS. 6D, 6E and 6F, the charged portion 250 of the expandable electrode 200 may be positioned at the terminus of the expandable electrode 200 after the spacer 230 such that the charge is applied to portions of the substrate 1000 as the charged portion 250 of the expandable electrode 200 passes through the substrate during electrodeposition. The charged portion 250 of the expandable electrode 200 may optionally be positioned behind the spacer 230 such that the charged portion 250 provides a charge to portions of the substrate 1000, and accordingly electrodeposits the electrodepositable coating composition 900, after the spacer 230 has moved past said section of the substrate 1000. This configuration may prevent the spacer 230 from producing defects in the applied coating while it moves through and potentially contacts the first surface 1010 of the substrate 1000.
The electrocoating system 10 may further comprise a means for counter-balancing 700 the movable electrode 200. Any suitable means for counter-balancing 700 may be used. For example, the means for counter-balancing 700 may comprise one or more air bladders or low-density materials, such as foam, attached to, or located within, the movable electrode 200 body that increase the buoyancy of the movable electrode 200 in the electrodepositable coating composition 900, as well as mechanical means for counter-balancing 700 the movable electrode 200, such as the spacer 230 described herein. The means for counter-balancing 700 the movable electrode 200 is meant to prevent sagging of the movable electrode 200 relative to the substrate 1000 that may result from the length of the movable electrode 200, including the length of the expandable electrode 200 in an expended state. The counter-balancing assists in ensuring uniform distance between the outer surface of the movable electrode 200 and the surface of the substrate 1000 that allows for the substrate 1000 to be coated substantially uniform. Accordingly, the means for counter-balancing 700 may help improve the uniformity of the charge density of the electrodepositable coating composition 900 during electrocoating as well as eliminate arcs that may result from contact of the movable electrode 200 with the substrate 1000 to be coated.
The tank 100 is also configured to contain, at least partially, a substrate 1000 for electrocoating by the electrocoating system 10. The substrate 1000 may be a grounded electrical conductor and may generally be substantially configured of a conductive substance, such as, for example, a metallic substance. The substrate 1000 serves as a counter-electrode in electrical communication with the stationary electrode(s) 800 (if present) and movable electrode(s) 200. The substrate 1000 may comprise any cross-sectional shape, or multiple cross-sectional shapes if the substrate 1000 does not have a uniform cross-sectional shape. The substrate may comprise any dimensions. The substrate 1000 may comprise an open-polygon cross-sectional shape, such as an open-pocket cross-sectional shape. The cross-sectional shape may comprise a generally rectangular or a generally round cross-sectional shape. The substrate may comprise a first surface 1010 and a second surface 1020. The first surface 1010 may comprise an internal surface of the substrate 1000, and the second surface 1020 may comprise an external surface of the substrate 1000. For example, as shown in FIGS. 2A and 2B, when the substrate 1000 has a generally rectangular cross-sectional shape, the first surface 1010 may comprise the internal surface of the substrate 1000, and the second surface 1020 may comprise the external surface of the substrate 1000. The substrate 1000 may comprise a container, such as, for example, an intermodal container. For example, the substrate 1000 may have an external length of about 8 feet (2.44 m) to about 53 feet (16.15 m), such as 8 feet (2.44 m), 10 feet (3.05 m), 20 feet (6.10 m), 40 feet (12.19 m), 45 feet (13.72 m) or 53 feet (16.15 m); an external width of about 7 feet (2.13 m) to about 8 feet (2.44 m), such as 7 feet (2.13 m) or 8 feet (2.44 m); and an external height of about 7.5 feet (2.29 m) to about 9.5 feet (2.90 m), such as 7.5 feet (2.29 m), 8.5 feet (2.59 m) or 9.5 feet (2.90 m). The substrate 1000 may have a length of at least 8 feet (2.44 m), such as at least 10 feet (3.05 m), such as at least 20 feet (6.10 m), such as at least 40 feet (12.19 m), such as at least 45 feet (13.72 m) or such as at least 53 feet (16.15 m).
The first surface 1010 of the substrate 1000 may have a surface area that varies based on the length of the substrate 1000. The first surface 1010 of the substrate 1000 may have a surface area of at least 285 ft²(26.48 m²), such as at least 340 ft²(31.59 m²), such as at least 600 ft²(55.74 m²), such as at least 1,145 ft²(106.37 m²), such as at least 1,275 ft²(118.45 m²), such as at least 1,490 ft²(138.43 m²). The first surface 1010 of the substrate 1000 may have a surface area of 285 ft²(26.48 m²) to 1,890 ft²(175.59 m²) or larger. With respect to a container, the surface area may vary depending upon the length of the substrate 1000. For example, the first surface 1010 of an 8-foot substrate 1000 may have a surface area of 285 ft²(26.48 m²) to 400 ft²(37.16 m²), the first surface 1010 of a 10-foot substrate 1000 may have a surface area of 340 ft²(31.59 m²) to 460 ft²(42.74 m²), the first surface 1010 of a 20-foot substrate 1000 may have a surface area of 600 ft²(55.74 m²) to 795 ft²(73.86 m²), the first surface 1010 of a 40-foot substrate 1000 may have a surface area of 1,145 ft²(106.37 m²) to 1,460 ft²(135.64 m²), the first surface 1010 of a 45-foot substrate 1000 may have a surface area of 1,275 ft²(118.45 m²) to 1,620 ft²(150.50 m²), and the first surface 1010 of a 53-foot substrate 1000 may have a surface area of 1,490 ft²(138.43 m²) to 1,890 ft²(175.59 m²).
The second surface 1020 of the substrate 1000 may have a surface area that varies based on the length of the substrate 1000. The second surface 1020 of the substrate 1000 may have a surface area of at least such as at least 330 ft²(30.66 m²), 380 ft²(35.30 m²), such as at least 675 ft²(62.71 m²), such as at least 1,250 ft²(116.13 m²), such as at least 1,390 ft²(129.14 m²), such as at least 1,630 ft²(151.43 m²). The second surface 1020 of the substrate 1000 may have a surface area of 330 ft²(30.66 m²) to 1,750 ft²(162.58 m²) or larger. With respect to a container, the surface area may vary depending upon the length of the substrate 1000. For example, the second surface 1020 of an 8-foot substrate 1000 may have a surface area of 330 ft²(30.66 m²) to 440 ft²(40.88 m²), the second surface 1020 of a 10-foot substrate 1000 may have a surface area of 380 ft²(35.30 m²) to 520 ft²(48.31 m²), the second surface 1020 of a 20-foot substrate 1000 may have a surface area of 675 ft²(62.71 m²) to 865 ft²(80.36 m²), the second surface 1020 of a 40-foot substrate 1000 may have a surface area of 1250 ft²(116.13 m²) to 1,575 ft²(146.32 m²), the second surface 1020 of a 45-foot substrate 1000 may have a surface area of 1,390 ft²(129.14 m²) to 1,750 ft²(162.58 m²), and the second surface 1020 of a 53-foot substrate 1000 may have a surface area of 1,630 ft²(151.43 m²) to 2,030 ft²(188.59 m²).
The substrate 1000 may have a cross-sectional area of at least 40 ft²(3.72 m²), such as at least 45 ft²(4.18 m²), such as at least 50 ft²(4.65 m²), and may be no more than 100 ft²(9.30 m²), such as no more than 85 ft²(7.90 m²), such as no more than 81 ft²(7.53 m²). The substrate 1000 may have a cross-sectional area of 40 ft²(3.72 m²) to 100 ft²(9.30 m²), such as 45 ft²(4.18 m²) to 85 ft²(7.90 m²), such as 50 ft²(4.65 m²) to 81 ft²(7.53 m²). As used herein, the term “cross-sectional area” with respect to the substrate 1000 refers to the largest cross-sectional area of the substrate as measured perpendicular to the longest axis of the substrate 1000. With respect to a container-shaped substrate 1000, the cross-sectional area will be the width multiplied by the height.
The substrate 1000 may comprise any conductive material. For example, the substrate 1000 may comprise a metal, metal alloy, and/or materials that have been metallized, such as nickel-plated plastic. Additionally, substrate 1000 may comprise non-metal conductive materials including composite materials such as, for example, materials comprising carbon fibers or conductive carbon. The metal or metal alloy may comprise, for example, cold rolled steel, hot rolled steel, steel coated with zinc metal, zinc compounds or zinc alloys, such as electrogalvanized steel, hot-dipped galvanized steel, galvanealed steel, nickel-plated steel, and steel plated with zinc alloy. The substrate 1000 may comprise an aluminum alloy. Non-limiting examples of aluminum alloys include the 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX or 8XXX series as well as clad aluminum alloys and cast aluminum alloys. The substrate 1000 may comprise a magnesium alloy. The substrate 1000 used in the present invention may also comprise other suitable non-ferrous metals such as titanium or copper, as well as alloys of these materials.
When the substrate 1000 is positioned at least partially inside the tank 100, the electrocoating system 10 may be configured such that the movable electrode 200 may be moved into a position generally closer to the substrate 1000. For example, as discussed above, the distance between the external surface of the movable electrode 200 may be at a distance of four feet or less from the surface of the substrate 1000 to be coated. For example, if the substrate 1000 comprises a cavity, such as a container or a pipe, the movable electrode 200 may positioned (or expanded) into the cavity of the substrate 1000 to be coated.
The electrocoating system 10 may further comprise at least one power source (not shown) to provide an electrical current to the electrocoating system 10. The power source may optionally include a rectifier. The power source is electrically coupled to the movable electrode 200, the substrate 1000, and, if present, the stationary electrodes 800, with one pole of the power source coupled to the substrate, and the other pole of the power source coupled to the movable electrode 200 and, if present, the stationary electrode(s) 800, such that the substrate 1000 serves as a counter-electrode to the movable electrode 200 and, if present, the stationary electrode(s) 800. For example, if the electrodepositable coating composition 900 is a cationic electrodepositable coating composition, the substrate 1000 serves as the cathode and the movable electrode 200 and, if present, stationary electrode 800 serve as anodes, with the polarities reversed for an anionic electrodepositable coating composition. The power source provides an electric current to the electrocoating system 10 such that the movable electrode 200 and, if present, stationary electrode 800, provide an electric charge to the electrodepositable coating composition 900 sufficient for electrocoating purposes. Specifically, when the power source provides an electrical current to the electrocoating system 10, the electrodepositable coating composition 900 is charged by the movable electrode 200 and, if present, the stationary electrode 800, and is attracted to, and deposits on, the oppositely-charged substrate 1000. Equal, or substantially equal, charge distribution throughout the electrically charged electrodepositable coating composition 900 around the substrate 1000 provided by the electrocoating system 10 of the present invention enhances the electrocoating process by generally providing a substantially uniform coating thickness of the electrodepositable coating composition 900 deposited onto the entire surface of the substrate 1000. For example, but not by way of limitation, the electric current provided to the power source may be, but is not limited to, about 25 volts to about 600 volts or higher. The electrocoating system 10 may also comprise any additional or other electrical circuitry desired or needed to perform the purposes stated herein.
As mentioned above, the electrocoating system 10 optionally may further comprise at least one stationary electrode 800 positioned inside the tank 100 to provide additional electric charge to the electrodepositable coating composition 900. The stationary electrode 800 may comprise any suitable conductive material known in the art. For example, the stationary electrode 800 may comprise a conductive pipe section electrically coupled with the power source. The stationary electrode(s) 800 may be membrane-free, or substantially membrane-free, or substantially covered by a membrane. The electrocoating system 10 may comprise a plurality of stationary electrodes 800, and the stationary electrodes 800 may be positioned along a length of the tank 100 such that the electrodepositable coating composition 900 is deposited substantially uniform along the length of the substrate 1000 to be electrocoated. For example, the stationary electrodes 800 may be positioned equidistant along a length of the tank 100. The electrocoating system 10 may be configured such that the ratio of a total combined surface area of the stationary electrode(s) 800 to the surface area of the second surface 1020 of the substrate 1000 may be from 1:7 to 1:1, such as 1:6 to 1:2, such as 1:5 to 1:3, such as 1:4.
Without intending to be bound by any theory, it is believed that the use of a stationary electrode 800 alone in an electrocoating system will not provide a sufficient charge to the electrodepositable coating composition 900 to enable a uniform deposition of the electrodepositable coating composition 900 over the entire surface of the substrate 1000 without the movable electrode 200 also being present. For example, the stationary electrode 800 may provide a sufficient charge to the electrodepositable coating composition 900 to deposit a coating on a surface of the substrate 1000 located near the stationary electrode 800, such as, for example, the second surface 1020 of the substrate 1000, but may not provide a sufficient charge to enable deposition of a continuous coating on other portions of the substrate, such as, for example, the first surface 1010 of the substrate 1000. The electrocoating system 10 of the present invention may allow for substantial or complete coverage of the first surface 1010 of the substrate 1000, for example, the electrocoating system may result in at least 70% of the total surface area of the first surface 1010 of the substrate 1000 to be coated with a coating deposited from the electrodepositable coating composition 900, such as at least 75%, such as at least 80%, such as at least 85%, such as at least 90%, such as at least 95%, such as at least 97%, such as at least 99%, such as 100%.
According to the present invention, the electrocoating system 10 may be free of an ion exchange membrane, such as an ion exchange membrane having an electrocatalyst applied onto a surface thereof.
The electrodepositable coating composition 900 may comprise any electrodepositable coating composition known in the art. As used herein, the term “electrodepositable coating composition” refers to a composition that is capable of being deposited onto an electrically conductive substrate under the influence of an applied electrical potential. For example, as mentioned above, the electrodepositable coating composition 900 may comprise a cationic or anionic electrodepositable coating composition.
The electrodepositable coating composition typically comprises a film-forming binder. The film-forming binder may comprise an ionic salt group-containing film-forming polymer and, optionally, a curing agent.
According to the present invention, the ionic salt group-containing film-forming polymer may comprise a cationic salt group-containing film-forming polymer. The cationic salt group-containing film-forming polymer may be used in a cationic electrodepositable coating composition. As used herein, the term “cationic salt group-containing film-forming polymer” refers to polymers that include at least partially neutralized cationic groups, such as sulfonium groups and/or ammonium groups, that impart a positive charge to the polymer. As used herein, the term “polymer” encompasses, but is not limited to, oligomers and both homopolymers and copolymers. The cationic salt group-containing film-forming polymer may comprise active hydrogen functional groups. As used herein, the term “active hydrogen functional groups” refers to those groups that are reactive with isocyanates as determined by the Zerewitinoff test described in the JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol. 49, page 3181 (1927), and include, for example, hydroxyl groups, primary or secondary amino groups, and thiol groups. Cationic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, cationic salt group-containing film-forming polymers.
Examples of polymers that are suitable for use as the cationic salt group-containing film-forming polymer in the present invention include, but are not limited to, alkyd polymers, acrylic polymers, polyepoxide polymers, polyamide polymers, polyurethane polymers, polyurea polymers, polyether polymers, and polyester polymers, among others.
The cationic salt groups may be incorporated into the cationic salt group-containing film-forming polymer as follows: The film-forming polymer may be reacted with a cationic salt group former. By “cationic salt group former” is meant a material which is reactive with epoxy groups present and which may be acidified before, during, or after reaction with the epoxy groups on the film-forming polymer to form cationic salt groups. Examples of suitable materials include amines such as primary or secondary amines which can be acidified after reaction with the epoxy groups to form amine salt groups, or tertiary amines which can be acidified prior to reaction with the epoxy groups and which after reaction with the epoxy groups form quaternary ammonium salt groups. Examples of other cationic salt group formers are sulfides which can be mixed with acid prior to reaction with the epoxy groups and form ternary sulfonium salt groups upon subsequent reaction with the epoxy groups.
More specific examples of suitable active hydrogen-containing, cationic salt group containing film-forming polymers include polyepoxide-amine adducts, such as the adduct of a polyglycidyl ether of a polyphenol, such as Bisphenol A, and primary and/or secondary amines, such as are described in U.S. Pat. No. 4,031,050 at col. 3, line 27 to col. 5, line 50, U.S. Pat. No. 4,452,963 at col. 5, line 58 to col. 6, line 66, and U.S. Pat. No. 6,017,432 at col. 2, line 66 to col. 6, line 26, these portions of which being incorporated herein by reference. A portion of the amine that is reacted with the polyepoxide may be a ketimine of a polyamine, as is described in U.S. Pat. No. 4,104,147 at col. 6, line 23 to col. 7, line 23, the cited portion of which being incorporated herein by reference. Also suitable are ungelled polyepoxide-polyoxyalkylenepolyamine resins, such as are described in U.S. Pat. No. 4,432,850 at col. 2, line 60 to col. 5, line 58, the cited portion of which being incorporated herein by reference. In addition, cationic acrylic resins, such as those described in U.S. Pat. No. 3,455,806 at col. 2, line 18 to col. 3, line 61 and U.S. Pat. No. 3,928,157 at col. 2, line 29 to col. 3, line 21, these portions of both of which are incorporated herein by reference, may be used.
Besides amine salt group-containing resins, the cationic salt group-containing film-forming polymer may comprise a quaternary ammonium salt group-containing resin. As used herein, a “quaternary ammonium salt group” refers to a group comprising a quaternary ammonium cation of the formula NR₄ ⁺, wherein each R group is independently an alkyl or aryl group, and a counter anion. Examples of these resins are those which are formed from reacting an organic polyepoxide with a tertiary amine acid salt. Such resins are described in U.S. Pat. No. 3,962,165 at col. 2, line 3 to col. 11, line 7; 3,975,346 at col. 1, line 62 to col. 17, line 25 and U.S. Pat. No. 4,001,156 at col. 1, line 37 to col. 16, line 7, these portions of which being incorporated herein by reference.
Examples of other suitable cationic resins include ternary sulfonium salt group-containing resins, such as those described in U.S. Pat. No. 3,793,278 at col. 1, line 32 to col. 5, line 20, this portion of which being incorporated herein by reference. Also, cationic resins which cure via a transesterification mechanism, such as described in European Patent Application No. 12463B1 at pg. 2, line 1 to pg. 6, line 25, this portion of which being incorporated herein by reference, may also be employed.
Other suitable cationic salt group-containing film-forming polymers include those that may form photodegradation resistant electrodepositable coating compositions. Such polymers include the polymers comprising cationic amine salt groups which are derived from pendant and/or terminal amino groups that are disclosed in U.S. Pat. Application Publication No. 2003/0054193 A1 at paragraphs [0064] to [0088], this portion of which being incorporated herein by reference. Also suitable are the active hydrogen-containing, cationic salt group-containing resins derived from a polyglycidyl ether of a polyhydric phenol that is essentially free of aliphatic carbon atoms to which are bonded more than one aromatic group, which are described in U.S. Pat. Application Publication No. 2003/0054193 A1 at paragraphs [0096] to [0123], this portion of which being incorporated herein by reference.
The active hydrogen-containing, cationic salt group-containing film-forming polymer may be made cationic and water dispersible by at least partial neutralization with an acid. Suitable acids include organic and inorganic acids. Non-limiting examples of suitable organic acids include formic acid, acetic acid, methanesulfonic acid, and lactic acid. Non-limiting examples of suitable inorganic acids include phosphoric acid and sulfamic acid. By “sulfamic acid” is meant sulfamic acid itself or derivatives thereof such as those having the formula:
wherein R is hydrogen or an alkyl group having 1 to 4 carbon atoms. Mixtures of the above-mentioned acids also may be used in the present invention.
The extent of neutralization of the cationic salt group-containing film-forming polymer may vary with the particular polymer involved. However, sufficient acid should be used to sufficiently neutralize the cationic salt-group containing film-forming polymer such that the cationic salt group-containing film-forming polymer may be dispersed in an aqueous dispersing medium. For example, the amount of acid used may provide at least 20% of all of the total theoretical neutralization. Excess acid may also be used beyond the amount required for 100% total theoretical neutralization. For example, the amount of acid used to neutralize the cationic salt group-containing film-forming polymer may be ≥0.1% based on the total amines in the active hydrogen-containing, cationic salt group-containing film-forming polymer. Alternatively, the amount of acid used to neutralize the active hydrogen-containing, cationic salt group-containing film-forming polymer may be ≤100% based on the total amines in the active hydrogen-containing, cationic salt group-containing film-forming polymer. The total amount of acid used to neutralize the cationic salt group-containing film-forming polymer may range between any combination of values, which were recited in the preceding sentences, inclusive of the recited values. For example, the total amount of acid used to neutralize the active hydrogen-containing, cationic salt group-containing film-forming polymer may be from about 20% to about 80%, such as 20%, 35%, 50%, 60%, or 80% based on the total amines in the cationic salt group-containing film-forming polymer.
The cationic salt group-containing film-forming polymer may be present in the cationic electrodepositable coating composition in an amount of at least 40% by weight, such as at least 50% by weight, such as at least 60% by weight, and may be present in an amount of no more than 90% by weight, such as no more than 80% by weight, such as no more than 75% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. The cationic salt group-containing film-forming polymer may for example be present in the cationic electrodepositable coating composition in an amount of 40% to 90% by weight, such as 50% to 80% by weight, such as 60% to 75% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. As used herein, the “resin solids” include the ionic salt group-containing film-forming polymer, the curing agent (if present), and any additional water-dispersible non-pigmented resinous component(s) present in the electrodepositable coating composition.
According to the present invention, the ionic salt group-containing film-forming polymer may comprise an anionic salt group-containing film-forming polymer. As used herein, the term “anionic salt group-containing film-forming polymer” refers to an anionic polymer comprising at least partially neutralized anionic functional groups, such as carboxylic acid and phosphoric acid groups that impart a negative charge. The anionic salt group-containing film-forming polymer may comprise active hydrogen functional groups. Anionic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, anionic salt group-containing film-forming polymers. The anionic salt group-containing film-forming polymer may be used in an anionic electrodepositable coating composition.
The anionic salt group-containing film-forming polymer may comprise base-solubilized, carboxylic acid group-containing film-forming polymers such as the reaction product or adduct of a drying oil or semi-drying fatty acid ester with a dicarboxylic acid or anhydride; and the reaction product of a fatty acid ester, unsaturated acid or anhydride and any additional unsaturated modifying materials which are further reacted with a polyol. Also suitable are the at least partially neutralized interpolymers of hydroxy-alkyl esters of unsaturated carboxylic acids, unsaturated carboxylic acid and at least one other ethylenically unsaturated monomer. Still another suitable anionic electrodepositable resin comprises an alkyd-aminoplast vehicle, i.e., a vehicle containing an alkyd resin and an amine-aldehyde resin. Another suitable anionic electrodepositable resin composition comprises mixed esters of a resinous polyol. Other acid functional polymers may also be used such as phosphatized polyepoxide or phosphatized acrylic polymers. Exemplary phosphatized polyepoxides are disclosed in U.S. Pat. Application Publication No. 2009-0045071 at [0004]-[0015] and U.S. patent application Ser. No. 13/232,093 at [0014]-[0040], the cited portions of which being incorporated herein by reference. Also suitable are resins comprising one or more pendent carbamate functional groups, such as those described in U.S. Pat. No. 6,165,338.
According to the present invention, the anionic salt group-containing film-forming polymer may be present in the anionic electrodepositable coating composition in an amount of at least 50% by weight, such as at least 55% by weight, such as at least 60% by weight, and may be present in an amount of no more than 90% by weight, such as no more than 80% by weight, such as no more than 75% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. The anionic salt group-containing film-forming polymer may be present in the anionic electrodepositable coating composition in an amount of 50% to 90%, such as 55% to 80%, such as 60% to 75%, based on the total weight of the resin solids of the electrodepositable coating composition.
According to the present invention, the electrodepositable coating composition of the present invention may further comprise a curing agent. The curing agent may be reactive with the ionic salt group-containing film-forming polymer. The curing agent comprises functional groups that react with the reactive functional groups, such as active hydrogen groups, of the ionic salt group-containing film-forming polymer to effectuate cure of the coating composition to form a coating. As used herein, the term “cure”, “cured” or similar terms, as used in connection with the electrodepositable coating compositions described herein, means that at least a portion of the components that form the electrodepositable coating composition are crosslinked to form a coating. Additionally, curing of the electrodepositable coating composition refers to subjecting said composition to curing conditions (e.g., elevated temperature) leading to the reaction of the reactive functional groups of the components of the electrodepositable coating composition, and resulting in the crosslinking of the components of the composition and formation of an at least partially cured coating. Non-limiting examples of suitable curing agents are at least partially blocked polyisocyanates, aminoplast resins and phenoplast resins, such as phenolformaldehyde condensates including allyl ether derivatives thereof.
Suitable at least partially blocked polyisocyanates include aliphatic polyisocyanates, aromatic polyisocyanates, and mixtures thereof. The curing agent may comprise an at least partially blocked aliphatic polyisocyanate. Suitable at least partially blocked aliphatic polyisocyanates include, for example, fully blocked aliphatic polyisocyanates, such as those described in U.S. Pat. No. 3,984,299 at col. 1 line 57 to col. 3 line 15, this portion of which is incorporated herein by reference, or partially blocked aliphatic polyisocyanates that are reacted with the polymer backbone, such as is described in U.S. Pat. No. 3,947,338 at col. 2 line 65 to col. 4 line 30, this portion of which is also incorporated herein by reference. By “blocked” is meant that the isocyanate groups have been reacted with a compound such that the resultant blocked isocyanate group is stable to active hydrogens at ambient temperature but reactive with active hydrogens in the film-forming polymer at elevated temperatures, such as between 90° C. and 200° C. The polyisocyanate curing agent may be a fully blocked polyisocyanate with substantially no free isocyanate groups.
The polyisocyanate curing agent may comprise a diisocyanate, higher functional polyisocyanates or combinations thereof. For example, the polyisocyanate curing agent may comprise aliphatic and/or aromatic polyisocyanates. Aliphatic polyisocyanates may include (i) alkylene isocyanates, such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (“HDI”), 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, ethylidene diisocyanate, and butylidene diisocyanate, and (ii) cycloalkylene isocyanates, such as 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,2-cyclohexane diisocyanate, isophorone diisocyanate, methylene bis(4-cyclohexylisocyanate) (“HMDI”), the cyclo-trimer of 1,6-hexamethylene diisocyanate (also known as the isocyanurate trimer of HDI, commercially available as Desmodur N3300 from Convestro AG), and meta-tetramethylxylylene diisocyanate (commercially available as TMXDI® from Allnex SA). Aromatic polyisocyanates may include (i) arylene isocyanates, such as m-phenylene diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate and 1,4-naphthalene diisocyanate, and (ii) alkarylene isocyanates, such as 4,4′-diphenylene methane (“MDI”), 2,4-tolylene or 2,6-tolylene diisocyanate (“TDI”), or mixtures thereof, 4,4-toluidine diisocyanate and xylylene diisocyanate. Triisocyanates, such as triphenyl methane-4,4′,4″-triisocyanate, 1,3,5-triisocyanato benzene and 2,4,6-triisocyanato toluene, tetraisocyanates, such as 4,4′-diphenyldimethyl methane-2,2′,5,5′-tetraisocyanate, and polymerized polyisocyanates, such as tolylene diisocyanate dimers and trimers and the like, may also be used. The curing agent may comprise a blocked polyisocyanate selected from a polymeric polyisocyanate, such as polymeric HDI, polymeric MDI, polymeric isophorone diisocyanate, and the like. The curing agent may also comprise a blocked trimer of hexamethylene diisocyanate available as Desmodur N3300® from Covestro AG. Mixtures of polyisocyanate curing agents may also be used.
The polyisocyanate curing agent may be at least partially blocked with at least one blocking agent selected from a 1,2-alkane diol, for example 1,2-propanediol; a 1,3-alkane diol, for example 1,3-butanediol; a benzylic alcohol, for example, benzyl alcohol; an allylic alcohol, for example, allyl alcohol; caprolactam; a dialkylamine, for example dibutylamine; and mixtures thereof. The polyisocyanate curing agent may be at least partially blocked with at least one 1,2-alkane diol having three or more carbon atoms, for example 1,2-butanediol.
Other suitable blocking agents include aliphatic, cycloaliphatic, or aromatic alkyl monoalcohols or phenolic compounds, including, for example, lower (e.g., C₁-C₆) aliphatic alcohols, such as methanol, ethanol, and n-butanol; cycloaliphatic alcohols, such as cyclohexanol; aromatic-alkyl alcohols, such as phenyl carbinol and methylphenyl carbinol; and phenolic compounds, such as phenol itself and substituted phenols wherein the substituents do not affect coating operations, such as cresol and nitrophenol. Glycol ethers and glycol amines may also be used as blocking agents. Suitable glycol ethers include ethylene glycol butyl ether, diethylene glycol butyl ether, ethylene glycol methyl ether and propylene glycol methyl ether. Other suitable blocking agents include oximes, such as methyl ethyl ketoxime, acetone oxime and cyclohexanone oxime.
The curing agent may comprise an aminoplast resin. Aminoplast resins are condensation products of an aldehyde with an amino- or amido-group carrying substance. Condensation products obtained from the reaction of alcohols and an aldehyde with melamine, urea or benzoguanamine may be used. However, condensation products of other amines and amides may also be employed, for example, aldehyde condensates of triazines, diazines, triazoles, guanidines, guanamines and alkyl- and aryl-substituted derivatives of such compounds, including alkyl- and aryl-substituted ureas and alkyl- and aryl-substituted melamines. Some examples of such compounds are N,N′-dimethyl urea, benzourea, dicyandiamide, formaguanamine, acetoguanamine, ammeline, 2-chloro-4,6-diamino-1,3,5-triazine, 6-methyl-2,4-diamino-1,3,5-triazine, 3,5-diaminotriazole, triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine, 3,4,6-tris(ethylamino)-1,3,5-triazine, and the like. Suitable aldehydes include formaldehyde, acetaldehyde, crotonaldehyde, acrolein, benzaldehyde, furfural, glyoxal and the like.
The aminoplast resins may contain methylol or similar alkylol groups, and at least a portion of these alkylol groups may be etherified by a reaction with an alcohol to provide organic solvent-soluble resins. Any monohydric alcohol may be employed for this purpose, including such alcohols as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol and others, as well as benzyl alcohol and other aromatic alcohols, cyclic alcohol such as cyclohexanol, monoethers of glycols such as Cello-solves and Carbitols, and halogen-substituted or other substituted alcohols, such as 3-chloropropanol and butoxyethanol.
Non-limiting examples of commercially available aminoplast resins are those available under the trademark CYMEL® from Allnex Belgium SA/NV, such as CYMEL 1130 and 1156, and RESIMENE® from INEOS Melamines, such as RESIMENE 750 and 753. Examples of suitable aminoplast resins also include those described in U.S. Pat. No. 3,937,679 at col. 16, line 3 to col. 17, line 47, this portion of which being hereby incorporated by reference. As is disclosed in the aforementioned portion of the '679 patent, the aminoplast may be used in combination with the methylol phenol ethers.
Phenoplast resins are formed by the condensation of an aldehyde and a phenol. Suitable aldehydes include formaldehyde and acetaldehyde. Methylene-releasing and aldehyde-releasing agents, such as paraformaldehyde and hexamethylene tetramine, may also be utilized as the aldehyde agent. Various phenols may be used, such as phenol itself, a cresol, or a substituted phenol in which a hydrocarbon radical having either a straight chain, a branched chain or a cyclic structure is substituted for a hydrogen at the aromatic ring. Mixtures of phenols may also be employed. Some specific examples of suitable phenols are p-phenylphenol, p-tert-butylphenol, p-tert-amylphenol, cyclopentylphenol and unsaturated hydrocarbon-substituted phenols, such as the monobutenyl phenols containing a butenyl group in ortho, meta or para position, and where the double bond occurs in various positions in the hydrocarbon chain.
Aminoplast and phenoplast resins, as described above, are further described in U.S. Pat. No. 4,812,215 at col. 6, line 20 to col. 7, line 12, the cited portion of which being incorporated herein by reference.
The curing agent may be present in the cationic electrodepositable coating composition in an amount of at least 10% by weight, such as at least 20% by weight, such as at least 25% by weight and may be present in an amount of no more than 60% by weight, such as no more than 50% by weight, such as no more than 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. The curing agent may be present in the cationic electrodepositable coating composition in an amount of 10% to 60% by weight, such as 20% to 50% by weight, such as 25% to 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition.
The curing agent may be present in the anionic electrodepositable coating composition in an amount of at least 10% by weight, such as at least 20% by weight, such as at least 25% by weight, and may be present in an amount of no more than 50% by weight, such as no more than 45% by weight, such as no more than 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. The curing agent may be present in the anionic electrodepositable coating composition in an amount of 10% to 50% by weight, such as 20% to 45% by weight, such as 25% to 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition.
The electrodepositable coating composition according to the present invention may optionally comprise one or more further components in addition to the film-forming binder and curing agent described above.
According to the present invention, the electrodepositable coating composition may optionally comprise a catalyst to catalyze the reaction between the curing agent and the polymers. Examples of catalysts suitable for cationic electrodepositable coating compositions include, without limitation, organotin compounds (e.g., dibutyltin oxide and dioctyltin oxide) and salts thereof (e.g., dibutyltin diacetate); other metal oxides (e.g., oxides of cerium, zirconium and bismuth) and salts thereof (e.g., bismuth sulfamate and bismuth lactate); or a cyclic guanidine as described in U.S. Pat. No. 7,842,762 at col. 1, line 53 to col. 4, line 18 and col. 16, line 62 to col. 19, line 8, the cited portions of which being incorporated herein by reference. Examples of catalysts suitable for anionic electrodepositable coating compositions include latent acid catalysts, specific examples of which are identified in WO 2007/118024 at paragraph [0031] and include, but are not limited to, ammonium hexafluoroantimonate, quaternary salts of SbF₆(e.g., NACURE® XC-7231), t-amine salts of SbF₆(e.g., NACURE® XC-9223), Zn salts of triflic acid (e.g., NACURE® A202 and A218), quaternary salts of triflic acid (e.g., NACURE® XC-A230), and diethylamine salts of triflic acid (e.g., NACURE® A233), all commercially available from King Industries, and/or mixtures thereof. Latent acid catalysts may be formed by preparing a derivative of an acid catalyst such as para-toluenesulfonic acid (pTSA) or other sulfonic acids. For example, a well-known group of blocked acid catalysts are amine salts of aromatic sulfonic acids, such as pyridinium para-toluenesulfonate. Such sulfonate salts are less active than the free acid in promoting crosslinking. During cure, the catalysts may be activated by heating.
According to the present invention, the electrodepositable coating composition may further comprise other optional ingredients, such as a pigment composition and/or various additives including fillers, plasticizers, anti-oxidants, biocides, UV light absorbers and stabilizers, hindered amine light stabilizers, defoamers, fungicides, dispersing aids, flow control agents, surfactants, wetting agents, pH adjusters, buffering agents, or combinations thereof. Alternatively, the electrodepositable coating composition may be completely free of any of the optional ingredients, i.e., the optional ingredient is not present in the electrodepositable coating composition. The pigment composition may comprise, for example, iron oxides, lead oxides, strontium chromate, coal dust, titanium dioxide, talc, barium sulfate, as well as color pigments such as cadmium yellow, cadmium red, chromium yellow and the like. The pigment content of the pigment composition, which excludes the electrically conductive particles described above, may be expressed as the pigment-to-binder weight ratio, and may be within the range of 0.03 to 0.1, when pigment is used. The other additives mentioned above may be present in the electrodepositable coating composition in amounts of 0.01% to 3% by weight, based on total weight of the resin solids of the electrodepositable coating composition.
According to the present invention, the electrodepositable coating composition typically comprises an aqueous dispersion medium comprising water and/or one or more organic solvent(s). Water can for example be present in amounts of 40% to 90% by weight, such as 50% to 80% by weight, such as 60% to 75% by weight, based on total weight of the electrodepositable coating composition. Examples of suitable organic solvents include oxygenated organic solvents, such as monoalkyl ethers of ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol which contain from 1 to 10 carbon atoms in the alkyl group, such as the monoethyl and monobutyl ethers of these glycols. Examples of other at least partially water-miscible solvents include alcohols such as ethanol, isopropanol, butanol and diacetone alcohol. If used, the organic solvents may typically be present in an amount of less than 10% by weight, such as less than 5% by weight, based on total weight of the electrodepositable coating composition. The electrodepositable coating composition may in particular be provided in the form of a dispersion, such as an aqueous dispersion.
According to the present invention, the total solids content of the electrodepositable coating composition may be at least 1% by weight, such as at least 10% by weight, such as at least 20% by weight, and may be no more than 60% by weight, such as no more than 40% by weight, such as no more than 20% by weight, based on the total weight of the electrodepositable coating composition. The total solids content of the electrodepositable coating composition may be from 1% to 60% by weight, such as 10% to 40% by weight, such as 20% to 30% by weight, based on the total weight of the electrodepositable coating composition.

Method for Coating a Substrate and Coated Substrates

The present invention is also directed to a method for coating a substrate comprising electrophoretically applying an electrodepositable coating composition 900 to at least a portion of the substrate 1000 using the electrocoating system 10 described above. The method may comprise positioning the substrate 1000 within the tank 100 wherein a surface of the substrate 1000 to be coated is at least partially submerged in the electrodepositable coating composition 900; positioning a movable electrode 200; electrically coupling the movable electrode 200 and the substrate 1000 to opposite poles of a power source; and then applying an electrical current to the electrocoating system 10 from the power source to electrodeposit the electrodepositable coating composition 900 onto the surface of the substrate 1000. For example, the substrate 1000 may be electrically coupled to the positive or negative terminal such that the substrate 1000 functions as a cathode or anode, respectively, during electrocoating, and the movable electrode 200 (and stationary electrode 800 if present) is connected to the opposite pole to serve as a counter-electrode to the substrate 1000. Once the movable electrode 200 is in position, the external surface of the movable electrode 200 may be at a distance of less than or equal to four feet from the surface of the substrate 1000 to be coated.
The substrate 1000 used in the method of the present invention may comprise a cavity. As discussed above, the substrate 1000 may comprise an open-polygon, polygon, or rounded cross-sectional shape having at least one open end and a cavity. For example, the substrate 1000 may be in the form of a container or a pipe having at least one open end and an internal cavity. In the method of the present invention, the movable electrode 200 may be positioned or expanded such that the movable electrode 200 enters the cavity of the substrate 1000. As mentioned above, the external surface of the movable electrode 200 may be at a distance of less than or equal to four feet from the surface of the substrate 1000 to be coated, such as less than or equal to 3.5 feet, such as less than or equal to 3 feet, such as less than or equal to 2.5 feet, such as less than or equal to 2 feet, such as less than or equal to 1.5 feet, such as less than or equal to 1 foot, such as less than or equal to 0.5 foot.
Following submersion of at least a portion of the substrate 1000 in the electrodepositable coating composition 900, an adherent film of the electrodepositable coating composition 900 is deposited on the substrate when a sufficient voltage is impressed between the electrodes (i.e., the substrate 1000 and the movable electrode(s) 200 and, if present, stationary electrode(s) 800) by the power source. The applied voltage may be varied and can be, for example, as low as one volt to as high as several thousand volts, such as between 25 and 600 volts. The current density may be between 0.5 ampere and 15 amperes per square foot.
The electrodepositable coating composition that may be used in the method of the present invention may comprise any of those known in the art, including those described above. For example, the electrodepositable coating composition may comprise a cationic film-forming resin comprising sulphonium groups and/or ammonium groups, or the electrodepositable coating composition may comprise an anionic electrodepositable coating composition comprising an anionic film-forming resin comprising carboxylic acid and/or phosphoric acid groups.
According to the present invention, the method may further comprise at least partially curing the electrophoretically applied electrodepositable coating composition on the substrate. As discussed above, at least partially curing the electrodepositable coating composition may comprise subjecting the substrate to elevated temperatures. With respect to cationic electrodepositable coating compositions, the coated substrate may be heated to a temperature ranging from, for example, 250° F. to 450° F. (121.1° C. to 232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.). With respect to anionic electrodepositable coating compositions, the coated substrate may be heated to a temperature ranging from, for example, 200° F. to 450° F. (93° C. to 232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.). The curing time may be dependent upon the curing temperature as well as other variables, for example, the film thickness of the electrodeposited coating, level and type of catalyst present in the composition, type of curing agent employed, and the like. For purposes of the present invention, all that is necessary is that the time be sufficient to effect cure of the coating on the substrate. For example, the curing time can range from 10 minutes to 60 minutes, such as 20 to 40 minutes. For example, the thickness of the resultant cured electrodeposited coating may range from 1 to 50 microns, such as 15 to 50 microns.
According to the present invention, the method for coating a substrate may comprise (a) electrophoretically depositing onto at least a portion of the substrate 1000 an electrodepositable coating composition 900 using the electrocoating system 10 of the present invention and (b) heating the coated substrate to a temperature and for a time sufficient to at least partially cure the electrodeposited coating composition 900 on the substrate. According to the present invention, the method may optionally further comprise (c) applying directly to the at least partially cured electrodeposited coating one or more pigment-containing coating compositions and/or one or more pigment-free coating compositions to form an additional coating layer over at least a portion of the at least partially cured electrodeposited coating, and (d) curing the additional coating layer by allowing it to set at ambient temperature or by applying a sufficient energy from an external energy source to the coated substrate of step (c) to a condition and for a time sufficient to at least partially cure the additional coating layer. Non-limiting examples of external energy sources include thermal energy and radiation such as ultraviolet, infrared or microwave.
The optional additional coating layer may comprise one or more primer layer(s) and suitable topcoat layer(s) (e.g., base coat, clearcoat layer, pigmented monocoat, and color-plus-clear composite compositions). It is understood that suitable additional coating layers include any of those known in the art, and each independently may be waterborne, solventborne, in solid particulate form (i.e., a powder coating composition), or in the form of a powder slurry. The additional coating compositions may comprise a film-forming polymer, crosslinking material and, if a colored base coat or monocoat, one or more pigments. The primer layer(s) may optionally be disposed between the electrocoating layer and the topcoat layer(s). Alternatively, the topcoat layer(s) may be omitted such that the composite comprises the electrocoating layer and one or more primer layer(s).
Moreover, the topcoat layer(s) may be applied directly onto the electrodepositable coating layer. In other words, the substrate may lack a primer layer such that the composite comprises the electrocoating layer and one or more topcoat layer(s). For example, a basecoat layer may be applied directly onto at least a portion of the electrodepositable coating layer.
It will also be understood that any of the topcoat layers may be applied onto an underlying layer despite the fact that the underlying layer has not been fully cured. For example, a clearcoat layer may be applied onto a basecoat layer even though the basecoat layer has not been subjected to a curing step (wet-on-wet). Both layers may then be cured during a subsequent curing step thereby eliminating the need to cure the basecoat layer and the clearcoat layer separately.
According to the present invention, additional ingredients such as colorants and fillers may be present in the various coating compositions from which the top coat layers result. Any suitable colorants and fillers may be used, such as those described above. For example, the colorant may be added to the coating in any suitable form, such as discrete particles, dispersions, solutions and/or flakes. A single colorant or a mixture of two or more colorants can be used in the coatings of the present invention. It should be noted that, in general, the colorant can be present in a layer of the multi-layer composite in any amount sufficient to impart the desired property, visual and/or color effect.
Example colorants include pigments, dyes and tints, such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA), as well as special effect compositions. A colorant may include, for example, a finely divided solid powder that is insoluble but wettable under the conditions of use. A colorant may be organic or inorganic and may be agglomerated or non-agglomerated. Colorants may be incorporated into the coatings by grinding or simple mixing. Colorants may be incorporated by grinding into the coating by use of a grind vehicle, such as an acrylic grind vehicle, the use of which will be familiar to one skilled in the art.
Example pigments and/or pigment compositions include, but are not limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone, condensation, metal complex, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketo pyrrolo pyrrole red (“DPP red BO”), titanium dioxide, carbon black, zinc oxide, antimony oxide, etc. and organic or inorganic UV opacifying pigments such as iron oxide, transparent red or yellow iron oxide, phthalocyanine blue and mixtures thereof. The terms “pigment” and “colored filler” can be used interchangeably.
Example dyes include, but are not limited to, those that are solvent and/or aqueous based such as acid dyes, azoic dyes, basic dyes, direct dyes, disperse dyes, reactive dyes, solvent dyes, sulfur dyes, mordant dyes, for example, bismuth vanadate, anthraquinone, perylene, aluminum, quinacridone, thiazole, thiazine, azo, indigoid, nitro, nitroso, oxazine, phthalocyanine, quinoline, stilbene, and triphenyl methane.
Example tints include, but are not limited to, pigments dispersed in water-based or water-miscible carriers such as AQUA-CHEM 896 commercially available from Degussa, Inc., CHARISMA COLORANTS and MAXITONER INDUSTRIAL COLORANTS commercially available from Accurate Dispersions division of Eastman Chemical, Inc.
The colorant may be in the form of a dispersion including, but not limited to, a nanoparticle dispersion. Nanoparticle dispersions can include one or more highly dispersed nanoparticle colorants and/or colorant particles that produce a desired visible color and/or opacity and/or visual effect. Nanoparticle dispersions may include colorants such as pigments or dyes having a particle size of less than 150 nm, such as less than 70 nm, or less than 30 nm. Nanoparticles may be produced by milling stock organic or inorganic pigments with grinding media having a particle size of less than 0.5 mm. Example nanoparticle dispersions and methods for making them are identified in U.S. Pat. No. 6,875,800 B2, which is incorporated herein by reference. Nanoparticle dispersions may also be produced by crystallization, precipitation, gas phase condensation, and chemical attrition (i.e., partial dissolution). In order to minimize re-agglomeration of nanoparticles within the coating, a dispersion of resin-coated nanoparticles may be used. As used herein, a “dispersion of resin-coated nanoparticles” refers to a continuous phase in which is dispersed discreet “composite microparticles” that comprise a nanoparticle and a resin coating on the nanoparticle. Example dispersions of resin-coated nanoparticles and methods for making them are identified in U.S. patent application Ser. No. 10/876,031 filed Jun. 24, 2004, which is incorporated herein by reference, and U.S. Provisional Pat. Application Ser. No. 60/482,167 filed Jun. 24, 2003, which is also incorporated herein by reference.
According to the present invention, special effect compositions that may be used in one or more layers of the multi-layer coating composite include pigments and/or compositions that produce one or more appearance effects such as reflectance, pearlescence, metallic sheen, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, goniochromism and/or color-change. Additional special effect compositions may provide other perceptible properties, such as reflectivity, opacity or texture. For example, special effect compositions may produce a color shift, such that the color of the coating changes when the coating is viewed at different angles. Example color effect compositions are identified in U.S. Pat. No. 6,894,086, incorporated herein by reference. Additional color effect compositions may include transparent coated mica and/or synthetic mica, coated silica, coated alumina, a transparent liquid crystal pigment, a liquid crystal coating, and/or any composition wherein interference results from a refractive index differential within the material and not because of the refractive index differential between the surface of the material and the air.
According to the present invention, a photosensitive composition and/or photochromic composition, which reversibly alters its color when exposed to one or more light sources, can be used in a number of layers in the multi-layer composite. Photochromic and/or photosensitive compositions can be activated by exposure to radiation of a specified wavelength. When the composition becomes excited, the molecular structure is changed and the altered structure exhibits a new color that is different from the original color of the composition. When the exposure to radiation is removed, the photochromic and/or photosensitive composition can return to a state of rest, in which the original color of the composition returns. For example, the photochromic and/or photosensitive composition may be colorless in a non-excited state and exhibit a color in an excited state. Full color-change may appear within milliseconds to several minutes, such as from 20 seconds to 60 seconds. Example photochromic and/or photosensitive compositions include photochromic dyes.
The photosensitive composition and/or photochromic composition may be associated with and/or at least partially bound to, such as by covalent bonding, a polymer and/or polymeric materials of a polymerizable component. In contrast to some coatings in which the photosensitive composition may migrate out of the coating and crystallize into the substrate, the photosensitive composition and/or photochromic composition associated with and/or at least partially bound to a polymer and/or polymerizable component in accordance with the present invention has minimal migration out of the coating. Example photosensitive compositions and/or photochromic compositions and methods for making them are identified in U.S. patent application Ser. No. 10/892,919 filed Jul. 16, 2004 and incorporated herein by reference.
The additional coating layers may be applied by a topcoat system. The topcoat system may comprise any equipment and/or method known in the art to apply a topcoat coating composition. For example, the topcoat system may comprise equipment to apply a powder coating composition or a liquid coating composition. For example, the topcoat system may comprise a spray gun, a brush, a roller, a tank for immersion coating, or combinations thereof. The topcoat system may optionally further comprise a spraybooth, and the spraybooth may optionally comprise a ventilation system.
As mentioned above, the coating composition may be a powder coating composition. As used herein, “powder coating composition” refers to a coating composition which is completely free of water and/or solvent. Accordingly, the powder coating composition disclosed herein is not synonymous to waterborne and/or solventborne coating compositions known in the art.
According to the present invention, the powder coating composition comprises (a) a film-forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. Examples of powder coating compositions that may be used in the present invention include the polyester-based ENVIROCRON line of powder coating compositions (commercially available from PPG Industries, Inc.) or epoxy-polyester hybrid powder coating compositions. Alternative examples of powder coating compositions that may be used in the present invention include low temperature cure thermosetting powder coating compositions comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,470,752, assigned to PPG Industries Ohio, Inc. and incorporated herein by reference); curable powder coating compositions generally comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,432,333, assigned to PPG Industries Ohio, Inc. and incorporated herein by reference); and those comprising a solid particulate mixture of a reactive group-containing polymer having a T_gof at least 30° C. (such as those described in U.S. Pat. No. 6,797,387, assigned to PPG Industries Ohio Inc. and incorporated herein by reference).
Suitable film-forming polymers that may be used in the powder coating composition of the present invention comprise a (poly)ester (e.g., polyester triglycidyl isocyanurate), a (poly)urethane, an isocyanurate, a (poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidene fluoride, or combinations thereof.
According to the present invention, the reactive functional group of the film-forming polymer of the powder coating composition comprises hydroxyl, carboxyl, isocyanate (including blocked (poly)isocyanate), primary amine, secondary amine, amide, carbamate, urea, urethane, vinyl, unsaturated ester, maleimide, fumarate, anhydride, hydroxyl alkylamide, epoxy, or combinations thereof.
Suitable curing agents (crosslinking agents) that may be used in the powder coating composition of present invention comprise an aminoplast resin, a polyisocyanate, a blocked polyisocyanate, a polyepoxide, a polyacid, a polyol, or combinations thereof.
After deposition of the powder coating composition, the coating is often heated to cure the deposited composition. The heating or curing operation is often carried out at a temperature in the range of from 150° C. to 200° C., such as from 170° C. to 190° C., for a period of time ranging from 10 to 20 minutes. According to the invention, the thickness of the resultant film is from 50 microns to 125 microns.
As mentioned above, the coating composition may be a liquid coating composition. As used herein, “liquid coating composition” refers to a coating composition which contains a portion of water and/or solvent. Accordingly, the liquid coating composition disclosed herein is synonymous to waterborne and/or solventborne coating compositions known in the art.
According to the present invention, the liquid coating composition may comprise, for example, (a) a film-forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. In other examples, the liquid coating may contain a film-forming polymer that may react with oxygen in the air or coalesce into a film with the evaporation of water and/or solvents. These film-forming mechanisms may require or be accelerated by the application of heat or some type of radiation such as ultraviolet or infrared. Examples of liquid coating compositions that may be used in the present invention include the SPECTRACRON® line of solvent-based coating compositions, the AQUACRON® line of water-based coating compositions, and the RAYCRON® line of UV cured coatings (all commercially available from PPG Industries, Inc.).
Suitable film-forming polymers that may be used in the liquid coating composition of the present invention may comprise a (poly)ester, an alkyd, a (poly)urethane, an isocyanurate, a (poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane, or combinations thereof.
According to the present invention, the reactive functional group of the film-forming polymer of the liquid coating composition may comprise hydroxyl, carboxyl, isocyanate (including blocked (poly)isocyanate), primary amine, secondary amine, amide, carbamate, urea, urethane, vinyl, unsaturated ester, maleimide, fumarate, anhydride, hydroxyl alkylamide, epoxy, or combinations thereof.
Suitable curing agents (crosslinking agents) that may be used in the liquid coating composition of the present invention may comprise an aminoplast resin, a polyisocyanate, a blocked polyisocyanate, a polyepoxide, a polyacid, a polyol, or combinations thereof.
In addition, a colorant and, if desired, various additives such as surfactants, wetting agents or catalyst can be included in the coating composition (electrodepositable, powder, or liquid). As used herein, the term “colorant” means any substance that imparts color and/or other opacity and/or other visual effect to the composition. The colorant can be added to the composition in any suitable form, such as discrete particles, dispersions, solutions and/or flakes. A single colorant or a mixture of two or more colorants can be used.
Example colorants include pigments, dyes and tints, such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA), as well as special effect compositions. A colorant may include, for example, a finely divided solid powder that is insoluble but wettable under the conditions of use. A colorant can be organic or inorganic and can be agglomerated or non-agglomerated. Colorants can be incorporated by use of a grind vehicle, such as an acrylic grind vehicle, the use of which will be familiar to one skilled in the art.
Example pigments and/or pigment compositions include, but are not limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone, condensation, metal complex, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketo pyrrolo pyrrole red (“DPPBO red”), titanium dioxide, carbon black and mixtures thereof. The terms “pigment” and “colored filler” can be used interchangeably.
Example dyes include, but are not limited to, those that are solvent and/or aqueous based such as phthalo green or blue, iron oxide, bismuth vanadate, anthraquinone, perylene, aluminum and quinacridone.
Example tints include, but are not limited to, pigments dispersed in water-based or water-miscible carriers such as AQUA-CHEM 896 commercially available from Degussa, Inc., CHARISMA COLORANTS and MAXITONER INDUSTRIAL COLORANTS commercially available from Accurate Dispersions division of Eastman Chemical, Inc.
As noted above, the colorant can be in the form of a dispersion including, but not limited to, a nanoparticle dispersion. Nanoparticle dispersions can include one or more highly dispersed nanoparticle colorants and/or colorant particles that produce a desired visible color and/or opacity and/or visual effect. Nanoparticle dispersions can include colorants such as pigments or dyes having a particle size of less than 150 nm, such as less than 70 nm, or less than 30 nm. Nanoparticles can be produced by milling stock organic or inorganic pigments with grinding media having a particle size of less than 0.5 mm. Example nanoparticle dispersions and methods for making them are identified in U.S. Pat. No. 6,875,800 B2, which is incorporated herein by reference. Nanoparticle dispersions can also be produced by crystallization, precipitation, gas phase condensation, and chemical attrition (i.e., partial dissolution). In order to minimize re-agglomeration of nanoparticles within the coating, a dispersion of resin-coated nanoparticles can be used. As used herein, a “dispersion of resin-coated nanoparticles” refers to a continuous phase in which is dispersed discreet “composite microparticles” that comprise a nanoparticle and a resin coating on the nanoparticle. Example dispersions of resin-coated nanoparticles and methods for making them are identified in U.S. Pat. Application Publication No. 2005-0287348 A1, filed Jun. 24, 2004, U.S. Provisional Pat. Application No. 60/482,167 filed Jun. 24, 2003, and U.S. patent application Ser. No. 11/337,062, filed Jan. 20, 2006, which is also incorporated herein by reference.
Example special effect compositions that may be used include pigments and/or compositions that produce one or more appearance effects such as reflectance, pearlescence, metallic sheen, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, goniochromism and/or color-change. Additional special effect compositions can provide other perceptible properties, such as opacity or texture. According to the invention, special effect compositions can produce a color shift, such that the color of the coating changes when the coating is viewed at different angles. Example color effect compositions are identified in U.S. Pat. No. 6,894,086, incorporated herein by reference. Additional color effect compositions can include transparent coated mica and/or synthetic mica, coated silica, coated alumina, a transparent liquid crystal pigment, a liquid crystal coating, and/or any composition wherein interference results from a refractive index differential within the material and not because of the refractive index differential between the surface of the material and the air.
According to the invention, a photosensitive composition and/or photochromic composition, which reversibly alters its color when exposed to one or more light sources, can be used. Photochromic and/or photosensitive compositions can be activated by exposure to radiation of a specified wavelength. When the composition becomes excited, the molecular structure is changed and the altered structure exhibits a new color that is different from the original color of the composition. When the exposure to radiation is removed, the photochromic and/or photosensitive composition can return to a state of rest, in which the original color of the composition returns. According to the invention, the photochromic and/or photosensitive composition can be colorless in a non-excited state and exhibit a color in an excited state. Full color-change can appear within milliseconds to several minutes, such as from 20 seconds to 60 seconds. Example photochromic and/or photosensitive compositions include photochromic dyes.
The photosensitive composition and/or photochromic composition can be associated with and/or at least partially bound to, such as by covalent bonding, a polymer and/or polymeric materials of a polymerizable component. In contrast to some coatings in which the photosensitive composition may migrate out of the coating and crystallize into the substrate, the photosensitive composition and/or photochromic composition associated with and/or at least partially bound to a polymer and/or polymerizable component have minimal migration out of the coating. Example photosensitive compositions and/or photochromic compositions and methods for making them are identified in U.S. patent application Ser. No. 10/892,919 filed Jul. 16, 2004, incorporated herein by reference.
In general, the colorant can be present in the coating composition in any amount sufficient to impart the desired visual and/or color effect. The colorant may comprise from 1% to 65% by weight, such as from 3% to 40% by weight or 5% to 35% by weight, with weight percent based on the total weight of the composition.
According to the present invention, the method may optionally further comprise pretreating the substrate with a pretreatment composition prior to applying the electrodepositable coating composition using the electrocoating system. As used herein, the term “pretreatment composition” refers to a composition that is capable of reacting with and chemically altering the substrate surface and binding to it to form a film that affords corrosion protection. Non-limiting examples of a pretreatment composition include zinc phosphate pretreatment compositions such as, for example, those described in U.S. Pat. Nos. 4,793,867 and 5,588,989, zirconium containing pretreatment compositions such as, for example, those described in U.S. Pat. Nos. 7,749,368 and 8,673,091, and the like. The pretreatment composition may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the invention, the pretreatment composition when applied to the substrate may be at a temperature ranging from, for example, 40° F. to 160° F. (4.4° C. to 71.1° C.), such as 60° F. to 110° F. (15.6° C. to 43.3° C.), such as 70° F. to 90° F. (21.1° C. to 32.2° C.). For example, the pretreatment process may be carried out at ambient or room temperature. The contact time is often from 1 second to 15 minutes, such as 4 seconds to 10 minutes, such as 5 seconds to 4 minutes.
Following the contacting with the pretreatment composition, the substrate optionally may be dried in place, e.g., air dried at room temperature or be dried with hot air, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as by drying the substrate in an oven at 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls. The substrate surface may be partially, or in some instances, completely dried prior to any subsequent contact of the substrate surface with any water, solutions, compositions, or the like. According to the present invention, following the contacting with the pretreatment composition, the substrate (either wet or dried) optionally may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents in order to remove any residue and then optionally may be dried, for example air dried or dried with hot air as described in the preceding sentence. According to the present invention, such water rinses may be eliminated and the substrate (either wet or dried in place) may be contacted with subsequent treatment compositions.
The pretreatment composition may be applied to the substrate by a pretreatment system. The pretreatment system may comprise tanks for immersion, brushes, rollers, spray guns, or combinations thereof to apply the pretreatment composition to the substrate. The pretreatment system may further comprise tanks, brushes, rollers, spray guns, or combinations thereof for applying rinse compositions, such as water, to the substrate after it is contacted with the pretreatment composition.
According to the present invention, the method may optionally further comprise priming the substrate with a priming composition prior to applying the electrodepositable coating composition using the electrocoating system. The priming composition may be used alone or in combination with the pretreatment composition or other treatments prior to applying the electrodepositable coating composition. The priming composition may comprise a metal-rich coating composition. As used herein, the term “metal-rich coating composition” refers to film-forming compositions that include an organic or inorganic binder and at least 65% by weight metal particles, based on the total solids weight of the coating composition. As used herein, the term “metal particles” refers to elemental (i.e., zerovalent) metal and metal alloy particles. As used herein, the term “particles” refers to material in the form of particulates, such as powder or dust, as well as flakes, and may be in the form of any shape, such as, for example, spherical, ellipsoidal, cubical, rod-shaped, disk-shaped, prism-shaped, and the like. The metal may comprise zinc, aluminum, or alloys thereof. The priming composition may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, electrostatic spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. It is appreciated that the metal-rich primer coatings can also be applied in dry forms such as powder or films. The metal-rich primer coatings formed from the priming composition can be applied to a dry film thickness of, for example, 2.5 to 500 microns.
After application of the priming composition to the substrate, a film formed on the surface of the substrate may be dried by driving solvent out of the film by heating or by an air-drying period. Suitable drying conditions will depend on the particular priming composition and/or application, but an exemplary drying time of from about 1 to 5 minutes at a temperature of about 60 to 250° F. (15.6 to 121° C.), such as 70 to 212° F. (27 to 100° C.) may be sufficient. More than one primer coating layer may be applied if desired. Between coats, the previously applied coat may be flashed; that is, exposed to ambient conditions for a desired amount of time.
After application of the priming composition to a substrate, the applied priming composition may be cured by any means known in the art. For example, the coating may be subjected to curing conditions sufficient to cure the priming composition. For example, the coating composition may be subjected to curing conditions such as ambient conditions, as discussed above, for a period of hours or days. Alternatively, the substrate may be subjected to curing conditions such as radiation (e.g., UV radiation) or heated to a temperature and for a time sufficient to cure the priming coating.
The priming composition may be applied to the substrate by a priming system. The priming system may comprise tanks for immersion, brushes, rollers, spray guns, or combinations thereof to apply the priming composition to the substrate. The priming system may further comprise tanks, brushes, rollers, spray guns, or combinations thereof for applying rinse compositions, such as water, to the substrate.
According to the present invention, the substrate may optionally be subjected to other treatments prior to electrocoating. For example, the substrate may be rinsed, cleaned, deoxidized, cleaned and deoxidized, anodized, acid pickled, plasma treated, laser treated, or ion vapor deposition (IVD) treated. At least a portion of the surface of the substrate may be cleaned by physical and/or chemical means, such as mechanically abrading the surface and/or cleaning/degreasing the surface with commercially available alkaline or acidic cleaning agents that are well known to those skilled in the art. These optional treatments may be used on their own or in combination with a pretreatment composition and/or a priming composition.
The present invention is also directed towards a substrate coated using the electrocoating system described above. The substrate may optionally be further coated using the topcoat system. Accordingly, the substrate comprises an electrocoating layer and an optional topcoat layer.
The present invention is also directed towards a substrate coated using the pretreatment system and electrocoating system, both as described above. The substrate may optionally be coated using the topcoat system. Accordingly, the substrate may comprise a pretreatment layer, an electrocoating layer and an optional topcoat layer.
The present invention is also directed towards a substrate coated using the priming system and electrocoating system, both as described above. The substrate may optionally be coated using the topcoat system. Accordingly, the substrate may comprise a priming layer, an electrocoating layer and an optional topcoat layer.
The present invention is also directed towards a substrate coated using the pretreatment system, priming system and electrocoating system, each as described above. The substrate may optionally be coated using the topcoat system. Accordingly, the substrate comprises a pretreatment layer, a priming layer, an electrocoating layer and an optional topcoat layer.
The present invention is also directed towards a substrate coated according to the method of the present invention.

System for Coating a Substrate

The present invention is also directed towards a system for coating a substrate comprising the electrocoating system as described above. The system for coating a substrate may optionally further comprise the pretreatment system, the priming system, the topcoat system, or any combination thereof. For example, the system for coating a substrate may comprise the pretreatment system for pretreating the substrate; the priming system for priming the substrate; the electrocoating system for electrocoating the substrate; and the topcoat system for applying a topcoat coating to the substrate. The system for coating a substrate may comprise any combination of the systems discussed above applied sequentially. For example, the system for coating a substrate may comprise the pretreatment system followed by the electrocoat system; the system for coating a substrate may comprise the pretreatment system followed by the electrocoat system followed by the topcoat system; the system for coating a substrate may comprise the priming system followed by the electrocoat system; the system for coating a substrate may comprise the priming system followed by the electrocoat system followed by the topcoat system; the system for coating a substrate may comprise the pretreatment system followed by the priming system followed by the electrocoat system; the system for coating a substrate may comprise the pretreatment system followed by the priming system followed by the electrocoat system followed by the topcoat system; or the system for coating a substrate may comprise the electrocoat system followed by the topcoat system.
In view of the foregoing, the present invention thus relates inter alia, without being limited thereto, to the following aspects: A first aspect is directed to 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. A second aspect is directed to the electrocoating system according to the first aspect, further comprising at least one means for positioning the movable electrode within the tank. A second aspect is directed to the electrocoating system of the second aspect, wherein the means for positioning the movable electrode within the tank comprises an apparatus positioned above the tank, the apparatus having an arm configured to position the expandable electrode within the tank. A fourth aspect is directed to the electrocoating system of the third aspect, wherein the apparatus comprises a cart positioned on at least one rail and is laterally moveable on the rail relative to the tank. A fifth aspect is directed to the electrocoating system according to any of the preceding aspects, wherein the movable electrode comprises an expandable electrode. A sixth aspect is directed to the electrocoating system of the fifth aspect, wherein the expandable electrode is positioned on the sidewall and is configured to expand away from the sidewall. A seventh aspect is directed to the electrocoating system of the fifth aspect, 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. An eighth aspect is directed to the electrocoating system of any one of the fifth through seventh aspects, further comprising at least one means for positioning, means for expanding and/or means for retracting the expandable electrode within the tank. A ninth aspect is directed to the electrocoating system according to any one of the fifth through eighth aspects, wherein the means for positioning, 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. A tenth aspect is directed to the electrocoating system of the ninth aspect, 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. An eleventh aspect is directed to the electrocoating system of the tenth aspect, further comprising 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. A twelfth aspect is directed to the electrocoating system of the eleventh aspect, wherein the system further comprises a means for further expanding the expandable electrode. A thirteenth aspect is directed to the electrocoating system according to any one of the ninth through twelfth aspects, wherein the means for expanding or means for further expanding 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. A fourteenth aspect is directed to the electrocoating system according to any one of the preceding aspects, wherein the expandable electrode comprises a telescoping electrode. A fifteenth aspect is directed to the electrocoating system according to the fourteenth aspect, 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. A sixteenth aspect is directed to the electrocoating system according to any one of the fifth through eighth aspects, wherein the expandable electrode comprises a flexible material comprising a rope or hose-like configuration. A seventeenth aspect is directed to the electrocoating system according to any one of the preceding aspects, further comprising a means for counter-balancing the expandable electrode in an expanded state. An eighteenth aspect is directed to the electrocoating system according to any one of the preceding aspects, further comprising at least one stationary electrode and/or being free of an ion exchange membrane. A nineteenth aspect is directed to the electrocoating system according to any one of the fifth through eighteenth aspects, wherein the expandable electrode further comprises a spacer. A twentieth aspect is directed to the electrocoating system according to any one of the preceding aspects, wherein the movable electrode is at least one of: (1) located entirely within the tank, (2) configured to be free of points of contact with the substrate to be coated, (3) having a surface that is free of electrocatalyst, (4) comprising a non-porous material, and/or (5) completely submerged in the electrodepositable coating composition. A twenty-first aspect is directed to the electrocoating system according to any one of the preceding aspects, 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. A twenty-second aspect is directed to the electrocoating system according to any one of the preceding aspects, further comprising a means for tilting and/or rotating the substrate to be coated. A twenty-third aspect is directed to the electrocoating system according to any one of the preceding aspects, wherein the movable electrode further comprises at least one protrusion. A twenty-fourth aspect is directed to a method for coating a substrate using the electrocoating system according to any one of preceding aspects, 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 a coating deposited from the electrodepositable coating composition onto the surface of the substrate. A twenty-fifth aspect is directed to the method according to the twenty-fourth aspect, wherein the substrate comprises a container having a cavity, and the movable electrode is positioned into the cavity. A twenty-sixth aspect is directed to the method according to any one of twenty-fourth or twenty-fifth aspects, 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. A twenty-seventh aspect is directed to a method for coating a substrate using the electrocoating system according to any one of the fifth through twenty-third aspects, 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; expanding the expandable electrode; electrically coupling the expandable electrode and the substrate to opposite poles of a power source; and then applying an electrical current from the power source to electrodeposit a coating deposited from the electrodepositable coating composition onto the surface of the substrate. A twenty-eighth aspect is directed to the method according to the twenty-seventh aspect, wherein the substrate comprises a container having a cavity, and the expandable electrode is expanded into the cavity. A twenty-ninth aspect is directed to a substrate coated by the method according to any one of the twenty-fourth through twenty-eighth aspects. A thirtieth aspect is directed to a system for coating a substrate comprising the electrocoating system according to any one of the preceding first through twenty-third aspects, and further comprising at least one of (1) a pretreatment system for pretreating the substrate prior to processing the substrate in the electrocoating system; (2) a priming system for priming the substrate prior to processing the substrate in the electrocoating system; and/or (3) a topcoat system for applying a topcoat coating to the substrate after processing the substrate in the electrocoating system.
For purposes of the detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be read as if prefaced by the word “about”, even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open-ended numerical range is described herein, all numbers, values, amounts, percentages, subranges and fractions within or encompassed by the numerical range are to be considered as being specifically included in and belonging to the original disclosure of this application as if these numbers, values, amounts, percentages, subranges and fractions had been explicitly written out in their entirety.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.
As used herein, unless indicated otherwise, a plural term can encompass its singular counterpart and vice versa, unless indicated otherwise. For example, although reference is made herein to “a” movable electrode, “a” telescoping section, “a” means for positioning the movable electrode within the tank, “an” arm, “a” cart, “a” rail, “a” leg, “a” means for expanding the expandable electrode, “a” means for retracting the expandable electrode, “a” means for counterbalancing the movable electrode, and “a” stationary electrode, a combination (i.e., a plurality) of these components can be used. In addition, in this application, the use of “or” means “and/or” unless specifically stated otherwise, even though “and/or” may be explicitly used in certain instances.
As used herein, “including”, “containing” and like terms are understood in the context of this application to be synonymous with “comprising” and are therefore open-ended and do not exclude the presence of additional undescribed or unrecited elements, materials, ingredients or method steps. As used herein, “consisting of” is understood in the context of this application to exclude the presence of any unspecified element, ingredient or method step. As used herein, “consisting essentially of” is understood in the context of this application to include the specified elements, materials, ingredients or method steps “and those that do not materially affect the basic and novel characteristic(s)” of what is being described.
As used herein, the terms “on”, “onto”, “applied on”, “applied onto”, “formed on”, “deposited on”, “deposited onto”, mean formed, overlaid, deposited, or provided on but not necessarily in contact with the surface. For example, an electrodepositable coating composition “deposited onto” a substrate does not preclude the presence of one or more other intervening coating layers of the same or different composition located between the electrodepositable coating composition and the substrate.
Whereas specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
It will be appreciated by skilled artisans that numerous modifications and variations are possible in light of the above disclosure without departing from the broad inventive concepts described and exemplified herein. Accordingly, it is therefore to be understood that the foregoing disclosure is merely illustrative of various exemplary aspects of this application and that numerous modifications and variations can be readily made by skilled artisans which are within the spirit and scope of this application and the accompanying claims.

Claims

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.