CN113260741A

CN113260741A - System for electrocoating an electrically conductive substrate

Info

Publication number: CN113260741A
Application number: CN201980067955.XA
Authority: CN
Inventors: B·A·施瓦兹; T·L·胡特奇恩森; D·J·塞菲尔; J·A·柏斯奥斯基; I·G·施温德曼; M·L·弗莱特; A·E·哈里森
Original assignee: PPG Industries Ohio Inc
Current assignee: PPG Industries Ohio Inc
Priority date: 2018-10-15
Filing date: 2019-10-14
Publication date: 2021-08-13
Also published as: EP3867424A1; US20210388525A1; KR20210072056A; BR112021007150A2; WO2020081447A1; MX2021004316A

Abstract

The invention relates to an electrocoating system for electrocoating a substrate (500), the system comprising: a tank (100) configured to contain an electrodepositable coating composition; at least one pump (200) in fluid communication with the tank; at least one return conduit (210) connecting the tank with the inlet of the pump; at least one recirculation conduit (300) comprising a first end in fluid communication with the outlet of the pump and a second end having at least one aperture, and the at least one recirculation conduit comprising at least one external electrode (400) positioned at least partially outside the tank. Also disclosed herein are methods of coating a substrate, systems for coating a substrate, and coated substrates.

Description

System for electrocoating an electrically conductive substrate

Technical Field

The present invention relates to an electrocoating system for electrocoating a substrate. The invention also relates to a system for coating a substrate, a method for coating a substrate, and a coated substrate.

Description of the background

Electrodeposition as a coating application method involves depositing a film-forming component on an electrically conductive substrate under the influence of an applied electrical potential. Electrodeposition is popular in the coatings industry as compared to non-electrophoretic coating methods because of its higher paint utilization, excellent corrosion resistance, and lower environmental pollution. However, some conductive substrates are more difficult to coat by electrodeposition due to a number of factors, including the shape and size of the substrate. For example, it may be difficult to coat both the interior and exterior surfaces of a substrate having the shape of an open bag (such as a shipping container) using conventional electrocoating systems. Accordingly, an electrocoating system capable of coating a wide variety of substrates is desired.

Disclosure of Invention

Disclosed herein is an electrocoating system for electrocoating a substrate, the system comprising: a tank configured to contain an electrodepositable coating composition; at least one pump in fluid communication with the tank; at least one return conduit connecting the tank with an inlet of the pump; at least one recirculation conduit comprising a first end in fluid communication with an outlet of the pump and a second end having at least one aperture, and comprising at least one external electrode positioned at least partially outside the tank, wherein: the substrate has a first surface and a second surface; the pump is configured to receive the electrodepositable coating composition from the return conduit and deliver the electrodepositable coating composition to the reservoir through the recirculation conduit; the external electrode is configured to provide an electric charge to the electrodepositable coating composition; and the recirculation conduit is configured to extend into the tank interior and position the aperture of the second end to deliver at least a portion of the charged electrodepositable coating composition to the first surface of the substrate.

Also disclosed herein is a method for coating a substrate comprising electrophoretically applying to at least a portion of the substrate a coating deposited with an electrodepositable coating composition using the electrocoating system of the present invention.

Further, substrates herein are disclosed as coated by the method of the present invention.

Further, also disclosed herein is a system for coating a substrate, comprising the electrocoating system of the present invention, and further comprising: a pretreatment system for pretreating the substrate prior to treating the substrate in the electrocoating system; a priming system for priming the substrate prior to treatment of the substrate in the electrocoating system; and/or a topcoat system for applying a topcoat coating to the substrate after treating the substrate in the electrocoating system.

Drawings

FIG. 1 is a schematic representation of an electrocoating system having a recirculation conduit that includes an external electrode and extends into a tank in accordance with the invention.

FIG. 2 is a schematic representation of the electrocoating system of FIG. 1 in which the insulation extends outward from the tank for the length of the recirculation line to the pump.

FIG. 3 is a diagram of the electrocoating system of FIG. 1 without an internal electrode.

Detailed Description

The present invention is directed to an electrocoating system for electrocoating a substrate. The present specification also discloses systems for coating a substrate, methods of coating a substrate, substrates coated according to one or more of the methods described herein and/or by using one or more of the systems described herein.

Electrocoating system

As shown in FIG. 1, the present invention is directed to an electrocoating system 10 for electrocoating a substrate, the system comprising: a tank 100 configured to contain an electrodepositable coating composition, at least one pump 200 in fluid communication with the tank 100, at least one return conduit 210 connecting the tank 100 to an inlet of the pump 200, at least one recirculation conduit 300 comprising a first end 310 in fluid communication with an outlet of the pump 200 and a second end 320 having at least one aperture 330, wherein the at least one recirculation conduit 300 comprises at least one external electrode 400 positioned at least partially outside the tank 100, wherein the substrate has a first surface and a second surface; the return conduit 210 is configured to connect the tank 100 to the inlet of the pump 200; the pump 200 is configured to receive the electrodepositable coating composition 600 from the return conduit 210 and deliver the electrodepositable coating composition 600 to the reservoir 100 through the recirculation conduit 300; the external electrode 400 is configured to provide an electric charge to the electrodepositable coating composition 600; also, the recirculation conduit 300 is configured to extend into the interior of the tank 100 and position the aperture 330 of the second end 320 to deliver at least a portion of the charged electrodepositable coating composition 600 to the first surface of the substrate.

In accordance with the present invention, and as shown in fig. 1,2 and 3, reservoir 100 is configured to contain an electrodepositable coating composition. Tank 100 may comprise any material known in the art. For example, the tank 100 may comprise plastic, metal with an insulating lining (such as metal with an internal plastic lining), or metal with an insulating coating. Tank 100 may comprise any geometric shape. For example, the tank 100 may be substantially rectangular or substantially circular or spherical. The tank 100 may include a base portion 110 and at least one sidewall 120 extending upwardly from the base portion 110 to form a cavity in which the electrodepositable coating composition 600 may be contained.

The tank 100 is further configured to at least partially contain a substrate 500 for electrocoating. The substrate 500 may be an electrically conductive conductor that is grounded, and may generally consist essentially of an electrically conductive substance (e.g., a metallic substance). The substrate 500 serves as a counter electrode in electrical communication with the one or more inner electrodes 400 (if present) and the one or more outer electrodes 400. The substrate 500 may include any cross-sectional shape, or may include multiple cross-sectional shapes if the substrate 500 does not have a uniform cross-sectional shape. The substrate may comprise any size. The substrate 500 may include a cross-sectional shape of an open polygon, such as a cross-sectional shape of an open pocket. The cross-sectional shape may comprise a substantially rectangular or substantially circular cross-sectional shape. The substrate may include a first surface 510 and a second surface 520. The first surface 510 may comprise an inner surface of the substrate 500 and the second surface 520 may comprise an outer surface of the substrate 500. For example, as shown in fig. 1,2, and 3, when the substrate 500 has a substantially rectangular cross-sectional shape, the first surface 510 may comprise an interior surface of the substrate 500 and the second surface 520 may comprise an exterior surface of the substrate 500. Substrate 500 may comprise a shipping container, such as an intermodal container. For example, the outer length of the substrate 500 may be 8 feet (2.44m), 10 feet (3.05m), 20 feet (6.10m), 40 feet (12.19m), 45 feet (13.72m), or 53 feet (16.15 m); the outer width may be 7 feet (2.13m) or 8 feet (2.44 m); the exterior height may be 7.5 feet (2.29m), 8.5 feet (2.59m), or 9.5 feet (2.90 m). The length of the substrate 500 may be at least 8 feet (2.44m), such as at least 10 feet (3.05m), such as at least 20 feet (6.10m), such as at least 40 feet (12.19m), such as at least 45 feet (13.72m), or such as at least 53 feet (16.15 m).

The first surface 510 of the substrate 500 may have a surface area that varies based on the length of the substrate 500. The surface area of the first surface 510 of the substrate 500 may be at least 285ft²(26.48m²) Such as at least 340ft²(31.59m²) Such as at least 600ft²(55.74m²) Such asAt least 1145ft²(106.37m²) Such as at least 1275ft²(118.45m²) Such as at least 1490ft²(138.43m²). The surface area of the first surface 510 of the substrate 500 may be 285ft²(26.48m²) To 1890ft²(175.59m²) Or larger. With respect to the shipping container, the surface area may vary depending on the length of the substrate 500. For example, the surface area of the first surface 510 of the 8-foot substrate 500 may be 285ft²(26.48m²) To 400ft²(37.16m²) The surface area of the first surface 510 of the 10 foot substrate 500 may be 340ft²(31.59m²) To 460ft²(42.74m²) The surface area of the first surface 510 of the 20 foot substrate 500 may be 600ft²(55.74m²) To 795ft²(73.86m²) The surface area of the first surface 510 of the 40 inch substrate 500 may be 1145ft²(106.37m²) To 1460ft²(135.64m²) The surface area of the first surface 510 of the 45 foot substrate 500 may be 1275ft²(118.45m²) To 1620ft²(150.50m²) And, the surface area of the first surface 510 of the 53-foot substrate 500 can be 1490ft²(138.43m²) To 1890ft²(175.59m²)。

The surface area of the second surface 520 of the substrate 500 may vary based on the length of the substrate 500. The surface area of the second surface 520 of the substrate 500 can be at least, such as at least 330ft²(30.66m²)，380ft²(35.30m²) Such as at least 675ft²(62.71m²) Such as at least 1250ft²(116.13m²) Such as at least 1390ft²(129.14m²) Such as at least 1630ft²(151.43m²). The surface area of the second surface 520 of the substrate 500 may be 330ft²(30.66m²) To 1750ft²(162.58m²) Or larger. With respect to the shipping container, the surface area may vary depending on the length of the substrate 500. For example, the surface area of the second surface 520 of the 8-foot substrate 500 may be 330ft²(30.66m²) To 440ft²(40.88m²) 10 feetThe surface area of the second surface 520 of the substrate 500 may be 380ft²(35.30m²) To 520ft²(48.31m²) The surface area of the second surface 520 of the 20 foot substrate 500 may be 675ft²(62.71m²) To 865ft²(80.36m²) The second surface 520 of the 40 inch substrate 500 can have a surface area of 1250ft²(116.13m²) To 1575ft²(146.32m²) The second surface 520 of the 45 foot substrate 500 may have a surface area of 1390ft²(129.14m²) To 1750ft²(162.58m²) And, the surface area of the second surface 520 of the 53-foot substrate 500 can be 1630ft²(151.43m²) To 2030ft²(188.59m²)。

The substrate may have at least 40m²(such as at least 45m²Such as at least 50m²) And may not exceed 100m in cross-sectional area²(such as not more than 85 m)²Such as not more than 80m²). The cross-sectional area of the substrate may be 40m²To 100m²Such as 45m²To 85m²Such as 50m²To 80m². As used herein, the term "cross-sectional area" with respect to a substrate refers to the largest cross-sectional area of the substrate measured perpendicular to the longest axis of the substrate. For a container shaped substrate, the cross-sectional area will be the width multiplied by the height.

The substrate may comprise any electrically conductive substrate. For example, the substrate may comprise a metal, metal alloy, and/or a material that has been metallized (such as nickel-plated plastic). Additionally, the substrate may comprise a non-metallic conductive material, including composite materials, such as materials comprising carbon fibers or conductive carbon. The metal or metal alloy may include, for example, cold rolled steel, hot rolled steel, steel coated with a zinc metal, zinc compounds or zinc alloys, such as electrogalvanized steel, hot-dip galvanized steel, nickel-plated steel, and zinc alloy-plated steel. The substrate may comprise an aluminum alloy. Non-limiting examples of aluminum alloys include the 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, or 7XXX series, as well as composite aluminum alloys and cast aluminum alloys. The substrate may comprise a magnesium alloy. The substrate used in the present invention may also comprise other suitable non-ferrous metals, such as titanium or copper, and alloys of these materials.

As illustrated in fig. 1,2 and 3, the electrocoating system 10 also includes a return conduit 210 that connects the tank 100 to the pump 200. The return conduit 210 is configured to recirculate the electrodepositable coating composition 600 from the reservoir 100 to the pump 200. The return conduit 210 may include any combination of tubing, hoses, valves, and any other fluid delivery device configured to perform the purposes set forth herein.

As shown in fig. 1,2 and 3, the pump 200 is in fluid communication with the tank 100. The pump 200 is configured to receive the electrodepositable coating composition 600 from the return conduit 210 and deliver the electrodepositable coating composition 600 to the reservoir 100 through the recirculation conduit 300. The recirculation conduit 300 includes a first end 310 in fluid communication with the outlet of the pump 200 and a second end 320 having at least one aperture 330. The recirculation conduit 300 is configured to extend into the interior of the tank 100 and be immersed in the electrodepositable coating composition and position the one or more apertures 320 of the second end 310 to deliver at least a portion of the electrodepositable coating composition 600 to the first surface 510 of the substrate 500. The return conduit 210, the pump 200, and the recirculation conduit 300 may be directly coupled to form at least one continuous and uninterrupted loop such that the electrodepositable coating composition 600 is restricted from flowing through the return conduit 210, the pump 200, and the recirculation conduit 300. As described herein, the pump 200 is configured to deliver the electrodepositable coating composition 600 into the reservoir 100 through the recirculation conduit 300 at a flow rate and pressure suitable for electrocoating the substrate 500. For example, but not by way of limitation, the pump can deliver the electrodepositable coating composition 600 to the tank 100 at a flow rate of about 0.1 liters/second to about 65.0 liters/second at a pressure of about 1psi to about 50psi (such as about 15psi to about 40 psi). The pump 200 may comprise, for example, a centrifugal pump. However, it is contemplated that any pump 200 configured to perform the purposes set forth herein may be used in the electrocoating system 10 of the present invention.

As shown in fig. 1,2 and 3, the outer electrode 400 is positioned outside the reservoir 100. The outer electrode 400 is configured to provide an electrical charge to the electrodepositable coating composition 600 that is delivered by the pump 200 through the recirculation conduit 300 into the reservoir 100. In this way, the outer electrode 400 provides an electrical charge to the electrodepositable coating composition 600 prior to delivering the electrodepositable coating composition 600 into the reservoir 100 for electrocoating. The pump 200 generally delivers the electrodepositable coating composition 600 through the external electrode 400 to the reservoir 100 through the recirculation conduit 300 at a flow rate suitable for the external electrode 400 to sufficiently charge the electrodepositable coating composition 600. The flow rate of the electrodepositable coating composition 600 delivered through the outer electrode 400 may vary depending on the volume of the electrodepositable coating composition 600 delivered by the pump 200 relative to the surface area of the outer electrode 400. For example, it is contemplated that as the volume of the electrodepositable coating composition 600 increases, the flow rate at which the electrodepositable coating composition 600 may be provided decreases to increase the contact time between the electrodepositable coating composition 600 and the external electrode 400 and to enable the external electrode 400 to substantially charge the electrodepositable coating composition 600. Likewise, it is contemplated that the increase in surface area of the outer electrode 400 requires less contact time with the outer electrode 400 to sufficiently charge the electrodepositable coating composition 600. The outer electrode 400 may be configured in any cross-sectional shape, such as tubular, flat, C-shaped, fan-shaped, or annular, and may comprise, for example, a conductive tube or pipe segment, such as a metal pipe. For example, the outer electrode 400 can have an inner surface configured to contact the electrodepositable coating composition 600, and the electrocoating system 10 can be configured such that the ratio of the total combined surface area of the outer surfaces of the one or more outer electrodes 400 to the surface area of the first surface 510 of the substrate 500 is 1:7 to 1:1, such as 1: 6 to 1: 2, such as 1: 5 to 1: 3, such as about 1: 4.

at least a portion of the recirculation conduit 300 comprises an external electrode, and the portion of the recirculation conduit 300 comprising the external electrode 400 is at least partially or completely located outside the tank 100. As used herein, at least partially or completely outside of reservoir 100 means that at least a portion of external electrode 400 is present outside of reservoir 100 and not immersed in electrodepositable coating composition 600, or that the entire external electrode 400 is located outside of reservoir 100 and not immersed in electrodepositable coating composition 600. In other words, at least a portion or all of recirculation conduit 300, including outer electrode 400, is not immersed in electrodepositable coating composition 600 contained within reservoir 100. Alternatively, substantially all of recirculation conduit 300 may include outer electrode 400. For example, the outer electrode 400 may comprise at least 50%, such as at least 60%, such as at least 75%, such as at least 85%, such as at least 95%, such as 100%, of the recirculation conduit 300. The remainder of recirculation conduit 300 may comprise a combination of non-conductive and/or conductive materials. Recirculation conduit 300 may include any combination of conduits, hoses, valves, and any other fluid delivery device configured to perform the purposes set forth herein.

The outer electrode 400 may be contained within an insulating member 410. The insulating member 410 may prevent a user of the electrocoating system 10 from being exposed to the charge of the outer electrode 400 when an electrical potential is applied to the electrocoating system 10. The insulating member 410 may alternatively or additionally be located on the recirculation conduit 300 extending into the tank 100. The insulating member 410 may include, for example, a polyvinyl chloride (PVC) pipe in which the outer electrode 400 is contained. However, it is contemplated that any insulating member 410 configured to perform the purposes set forth herein may be utilized in accordance with the electrocoating system 10 of the present invention.

Further, if the external electrode 400 includes an anode, a film may be used to cover the inner surface of the external electrode 400 in order to remove accumulated acid from the electrodepositable coating composition 600 during the electrocoating process of the substrate 500. For example, about 50% (such as about 75%, such as about 80% or more) of the inner surface area of the outer electrode 400 may be covered by a film to control the pH of the electrodepositable coating composition by removing acid generated during electrocoating. The membrane covered anode is commonly referred to in the industry as an anolyte cell. The substantially film-free outer electrode 400 is an outer electrode that is film-free to the extent that any existing film does not interfere, to any significant extent, with the charging of the electrodepositable coating composition 600 by the outer electrode 400. In addition, the external electrode 400 may be completely film-free.

The outer electrode 400 may comprise, for example, a type 316 stainless steel tube without a membrane. The fully exposed walls of the channels of the film-free metal conduit outer electrode 400 in combination with the flow of the electrodepositable coating composition 600 through the outer electrode 400 may help the outer electrode 400 provide a substantially uniform charge to the electrodepositable coating composition 600 to promote a substantially equal charge distribution throughout the electrodepositable coating composition 600. The substantially equal charge distribution throughout the electrodepositable coating composition 600 optimizes the electrocoating of the substrate 500 by providing a substantially uniform attraction of the charged molecules of the electrodepositable coating composition 600 to the oppositely charged substrate 500. Further, it is contemplated that as the volume of the electrodepositable coating composition 600 delivered by the pump 200 to the outer electrode 400 increases, a greater surface area of the outer electrode 400 may be provided to allow for sufficient charging of the electrodepositable coating composition 600 delivered by the pump 200. Thus, it is contemplated that a minimum surface area of the outer electrode 400 may be provided for a flow of the electrodepositable coating composition 600 per unit volume to sufficiently charge the electrodepositable coating composition 600 prior to delivery of the electrodepositable coating composition 600 to the reservoir 100 for electrocoating the substrate 500. As discussed above, the surface area of the outer electrode 400 may be manipulated by, for example, increasing the length of the outer electrode 400 (i.e., increasing the length of the portion of the recirculation conduit 300 that includes the outer electrode 400, or increasing the length of the recirculation conduit 300 if the entire recirculation conduit 300 includes the outer electrode 400), or changing the cross-sectional shape of the outer electrode 400.

The second end 320 of the recirculation conduit 300 may include a nozzle that includes an aperture 330. The nozzle may comprise any nozzle known in the art. In addition, the second end 320 of the recirculation conduit 300 may include a plurality of apertures 330, and the electrodepositable coating composition 600 may pass through the plurality of apertures 330. The recirculation conduit may also include a plurality of second ends 320. For example, as shown in fig. 1,2 and 3, the recirculation conduit may branch, each branch including a second end 320, the second end 320 including at least one aperture 330. Each second end 320 of the branched recirculation conduit 300 may be configured to deliver at least a portion of the electrodepositable coating composition 600 charged by the outer electrode 400 to a different portion of the first surface 510 of the substrate 500.

As discussed above, the electrocoating system 10 may include multiple return conduits 210, pumps 200, and/or recirculation lines 300. For example, the electrocoating system 10 can include a plurality of recirculation conduits 300, the plurality of recirculation conduits 300 configured to deliver the electrodepositable coating composition 600 charged by the one or more external electrodes 400 to different portions of the first surface 510 of the substrate 500. Each recirculation conduit 300 may be supplied by a different pump 200, or the pumps 200 may pump the electrodepositable coating composition 600 to multiple recirculation conduits 300. Also, each pump 200 may be supplied by a return conduit 210, or a return conduit 210 may supply multiple pumps 200. The number of each component (i.e., the return conduit 210, the pump 200, the recirculation conduit 300) present in the electrocoating system 10 can depend on various factors including, for example, the length of the substrate 500, the surface area of the first surface 510 of the substrate 500, the resin solids present in the electrodepositable coating composition 600, the charge density of the electrodepositable coating composition 600, the voltage applied during electrocoating of the substrate, the shape of the substrate, and the like. The return conduit 210, pump 200, and/or recirculation line 300 can be positioned along the length of the tank 100 such that the electrodepositable coating composition 600 is substantially uniformly deposited along the length of the substrate 500 to be electrocoated. For example, the return conduit 210, the pump 200, and/or the recirculation conduit 300 may be positioned equidistantly along the length of the tank 100. The electrodepositable coating composition 600 flowing into the reservoir 100 through the recirculation conduit 300 may be substantially deposited on the first surface 510 of the substrate 500 during electrocoating. Without being bound by any theory, it is believed that positioning the recirculation conduit 300 of the electrocoating system 10 within the reservoir 100 to provide a flow of the electrodepositable coating composition 600 charged by the outer electrode 400 to the first surface 510 of the substrate 500 allows for deposition of a more uniform coating to be applied to the first surface 510 of the substrate 500, as compared to an electrocoating system that does not include the recirculation conduit 300 and the outer electrode 400.

When a power source provides current to the electrocoating system 10, the electrodepositable coating composition 600 is charged by the outer electrode 400 and the inner electrode 700 (if present), and attracted to and deposited on the oppositely charged substrate 500. The equal or substantially equal charge distribution throughout the charged fluid 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 500 deposited on the substrate 500.

As shown in fig. 1 and 2, optionally, the electrocoating system 10 may further include at least one internal electrode 700 positioned inside the reservoir 100 to provide additional electrical charge to the electrodepositable coating composition 600. The inner electrode 700 may comprise any suitable conductive material known in the art. For example, the inner electrode 700 may include a tube electrically coupled to a power source. The one or more inner electrodes 700 may be film-free, or substantially covered by a film. The electrocoating system 10 may include a plurality of internal electrodes 700, and the internal electrodes 700 may be positioned along the length of the tank 100 such that the electrodepositable coating composition 600 is substantially uniformly deposited along the length of the substrate 500 to be electrocoated. For example, the inner electrodes 700 may be positioned equidistantly along the length of the tank 100. Electrocoating system 10 may be configured such that the ratio of the total combined surface area of the one or more internal electrodes 700 to the surface area of second surface 510 of substrate 500 may be 1:7 to 1:1, such as 1: 6 to 1: 2, such as 1: 5 to 1: 3, such as 1: 4. in contrast to the recirculation conduit 300 including the outer electrode 400, the inner electrode 700 no longer circulates or transports the electrodepositable coating composition 600 within the electrocoating system 10.

Without being bound by any theory, it is believed that the use of the inner electrode 700 in an electrocoating system without the recirculation conduit 300 including the outer electrode 400 will not provide sufficient charge to the electrodepositable coating composition 600 to cause uniform deposition of the electrodepositable coating composition 600 over the entire surface of the substrate 500. For example, the inner electrode 700 may provide sufficient charge to the electrodepositable coating composition 600 to deposit a coating on a surface of the substrate 500 (e.g., the second surface 520 of the substrate 500) that is positioned adjacent to the inner electrode 700, but may not provide sufficient charge to enable deposition on other portions of the substrate (e.g., the first surface 510 of the substrate 500).

The electrocoating system 10 further includes at least one power source (not shown) to provide electrical current to the electrocoating system 10. Optionally, the power supply may include a rectifier. A power source is electrically coupled to the one or more outer electrodes 400, the substrate 500, and the inner electrode 700 (if present), wherein one pole of the power source is coupled to the substrate and the other pole of the power source is coupled to the one or more outer electrodes 400 and the one or more inner electrodes 700 (if present), such that the substrate serves as a counter electrode to the outer electrode 400 and the inner electrode 700 (if present). For example, if the electrodepositable coating composition 600 is a cationic electrodepositable coating composition, the substrate 500 functions as a cathode, and the outer electrode 400 and the inner electrode 400 (if present) function as an anode, wherein the polarity is opposite to that of the anionic electrodepositable coating composition. The power supply provides current to the electrocoating system 10 such that the outer electrode 400 and the inner electrode 700 (if present) provide sufficient charge to the electrodepositable coating composition 600 for electrocoating purposes. For example, but not by way of limitation, the current provided to the power source may be, but is not limited to, about 25 volts to about 600 volts or more. The voltage supplied to the power source may vary depending on the volume of the electrodepositable coating composition 600 delivered by the pump 200. For example, a higher voltage may be provided to the outer electrode 400 to substantially charge an increased volume and/or an increased flow rate of the electrodepositable coating composition 600 delivered by the pump 200. The electrocoating system 10 may also include any additional or other circuitry desired or necessary to carry out the purposes set forth herein.

The electrodepositable coating composition 600 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 on a conductive substrate under the influence of an applied electrical potential. For example, as mentioned above, the electrodepositable coating composition 600 may comprise a cationic or anionic electrodepositable coating composition.

The electrodepositable coating composition comprises a film-forming binder. The film-forming binder can include a film-forming polymer containing ionic salt groups and optionally a curing agent.

In accordance with the present invention, the ionic salt group-containing film-forming polymer can comprise a cationic salt group-containing film-forming polymer. Film-forming polymers containing cationic salt groups can be used in cationic electrodepositable coating compositions. As used herein, the term "cationic salt group-containing film-forming polymer" refers to a polymer that includes 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" includes, but is not limited to, oligomers, and both homopolymers and copolymers. The cationic salt group-containing film-forming polymer can include 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 zerewitinoff test as described in juournal OF THE AMERICAN CHEMICAL societiy (1927), volume 49, page 3181), and includes, for example, hydroxyl, primary or secondary amino, and thiol groups. A cationic salt group-containing film-forming polymer comprising active hydrogen functional groups can be referred to as an active hydrogen-containing, cationic salt group-containing film-forming polymer.

Examples of polymers suitable for use as cationic salt group-containing film-forming polymers 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.

Cationic salt groups can be incorporated into a film-forming polymer containing cationic salt groups as follows: the film-forming polymer can be reacted with a cationic salt group former. By "cationic salt group former" is meant a material that reacts with epoxy groups present and can be acidified to form cationic salt groups before, during, or after reaction with epoxy groups on the film-forming polymer. Examples of suitable materials include amines (such as primary or secondary amines) which can be acidified to form amine salt groups after reaction with an epoxy group; or a tertiary amine which is capable of being acidified prior to reaction with the epoxy group and which forms a quaternary ammonium salt group upon reaction with the epoxy group. Examples of other cationic salt group formers are sulfides, which can be mixed with an acid prior to reaction with an epoxy group and form a ternary sulfonium salt group upon subsequent reaction with an epoxy group.

More specific examples of suitable active hydrogen-containing, cationic salt group-containing film-forming polymers include polyepoxide-amine adducts, such as adducts of polyglycidyl ethers of polyphenols (such as bisphenol a) with primary and/or secondary amines, such as described in column 3, line 27 to column 5, line 50 of U.S. patent No. 4,031,050, column 5, line 58 to column 6, line 66 of U.S. patent No. 4,452,963, and column 2, line 66 to column 6, line 26 of U.S. patent No. 6,017,432, which portions are incorporated herein by reference. A portion of the amine reacted with the polyepoxide may be a ketimine of a polyamine, as described in column 6, line 23 to column 7, line 23 of U.S. patent No. 4,104,147, which portions of the above-identified documents are incorporated herein by reference. Ungelled polyepoxide-polyoxyalkylene polyamine resins are also suitable, such as those described in U.S. patent No. 4,432,850 at column 2, line 60 to column 5, line 58, the portions of which are set forth above being incorporated herein by reference. Additionally, cationic acrylic resins may be used, such as those described in U.S. Pat. No. 3,455,806 at column 2, line 18 to column 3, line 61 and U.S. Pat. No. 3,928,157 at column 2, line 29 to column 3, line 21, the portions of which are incorporated herein by reference.

In addition to the amine salt group-containing resin, the cationic salt group-containing film-forming polymer can also include a quaternary ammonium salt group-containing resin. As used herein, "quaternary ammonium salt group" is meant to include the formula NR₄ ⁺And a counter-anionic group, wherein each R group is independently an alkyl or aryl group. Examples of these resins are those formed by reacting an organic polyepoxide with a tertiary amine acid salt. Such resins are described in U.S. patent No. 3,962,165, column 2, line 3 to column 11, line 7, U.S. patent No. 3,975,346, column 1, line 62 to column 17, line 25, and U.S. patent No. 4,001,156, column 1, line 37 to column 16, line 7, the portions of which are incorporated herein by reference.

Examples of other suitable cationic resins include resins containing tertiary sulfonium salt groups, such as those described in U.S. Pat. No. 3,793,278 at column 1, line 32 to column 5, line 20, which is incorporated herein by reference. Furthermore, cationic resins that cure by a transesterification mechanism may also be employed, such as described in european patent application No. 12463B1, page 2, line 1 to page 6, line 25, which is incorporated herein by reference.

Other suitable cationic salt group-containing film-forming polymers include those that can form electrodepositable coating compositions that are resistant to photodegradation. Such polymers include polymers comprising cationic amine salt groups derived from pendant and/or terminal amino groups disclosed in paragraphs [0064] through [0088] of U.S. patent application publication No. 2003/0054193a1, which is incorporated herein by reference. Also suitable are active hydrogen-containing, cationic salt group-containing resins derived from polyglycidyl ethers of polyhydric phenols which are substantially free of aliphatic carbon atoms bonded to multiple aromatic groups, as described in U.S. patent application No. 2003/0054193a1, paragraphs [0096] to [0123], which is incorporated herein by reference.

Active hydrogen-containing, cationic salt group-containing film-forming polymers can 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. "sulfamic acid" means sulfamic acid by 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 acids may also be used in the present invention.

The degree of neutralization of the cationic salt group-containing film-forming polymer can vary depending on the particular polymer involved. However, sufficient acid should be used to sufficiently neutralize the cationic salt group-containing film-forming polymer so that the cationic salt group-containing film-forming polymer can be dispersed in the aqueous dispersion medium. For example, the amount of acid used may provide at least 20% of the total theoretical neutralization. The excess acid may also be used in an amount exceeding the amount required for a theoretical total neutralization of 100%. For example, the amount of acid used to neutralize the cationic salt group-containing film-forming polymer can 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 can 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 can vary between any combination of the values recited in the preceding sentence, 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 can be 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 component at least 40% by weight (such as at least 50% by weight, such as at least 60% by weight), and may be present at 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 resin solids of the electrodepositable coating component. The cationic salt group-containing film-forming polymer can be present in the cationic electrodepositable coating component from 40% to 90% by weight (such as from 50% to 80% by weight, such as from 60% to 75% by weight), based on the total weight of resin solids of the electrodepositable coating component. As used herein, "resin solids" include the ionic salt group-containing film-forming polymer present in the electrodepositable coating composition, the curing agent (if present), and any additional one or more water-dispersible non-pigment components.

In accordance with the present invention, the ionic salt group-containing film-forming polymer can comprise a film-forming polymer comprising anionic salt groups. As used herein, the term "anionic salt group-containing film-forming polymer" refers to an anionic polymer that includes at least partially neutralized anionic functional groups, such as negatively charged carboxylic and phosphoric acid groups.

The anionic salt group-containing film-forming polymer can include active hydrogen functional groups. Anionic salt group-containing film-forming polymers comprising active hydrogen functional groups can be referred to as active hydrogen-containing, anionic salt group-containing film-forming polymers. Film-forming polymers containing anionic salt groups can be used in anionic electrodepositable coating compositions.

The anionic salt group-containing film-forming polymer can include base-solubilized carboxylic acid group-containing film-forming polymers, such as reaction products or adducts of dried oil or semi-dried fatty acid esters with dicarboxylic acids or anhydrides; and the reaction product of a fatty acid ester, unsaturated acid or anhydride and any additional unsaturated modifying material that is further reacted with a polyol. Also suitable are at least partially neutralized interpolymers of hydroxyalkyl esters of unsaturated carboxylic acids, unsaturated carboxylic acids and at least one other ethylenically unsaturated monomer. Another suitable anionic electrodepositable resin includes an alkyd-aminoplast vehicle, i.e., a vehicle comprising an alkyd resin and an amine-aldehyde resin. Another suitable anionic electrodepositable resin component comprises a mixed ester of a resin polyol. Other acid functional polymers, such as phosphorylated polyepoxides or phosphorylated acrylic polymers, may also be used. Exemplary phosphorylated polyepoxides are disclosed in paragraphs [0004] to [0015] of U.S. patent application publication No. 2009-0045071 and paragraphs [0014] to [0040] of U.S. patent application No. 13/232,093, the portions of which are incorporated herein by reference. Resins comprising one or more urethane side groups are also suitable, such as those described in U.S. patent 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 component 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 resin solids of the electrodepositable coating component. The anionic salt group-containing film-forming polymer can be present in the anionic electrodepositable coating composition in an amount of from 50% to 90%, such as from 55% to 80%, such as from 60% to 75%, based on the total weight of 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 can be reacted with a film-forming polymer containing ionic salt groups. The curing agent includes functional groups that react with reactive functional groups (such as active hydrogen groups) of the ionic salt group-containing film-forming polymer to effect curing of the coating component to form the coating. As used herein, the terms "cure," "cured," or similar terms used in connection with the electrodepositable coating composition described herein mean that at least a portion of the ingredients forming the electrodepositable coating composition are crosslinked to form a coating. Additionally, curing of the electrodepositable coating composition means subjecting the composition to curing conditions (e.g., elevated temperature) to cause the reactive functional groups of the components of the electrodepositable coating composition to react and cause the components of the electrodepositable coating composition to crosslink and form 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 phenolic 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 column 1, line 57 to column 3, line 15, the portions of which are incorporated herein by reference), or partially blocked aliphatic polyisocyanates that react with the polymer backbone (such as those described in U.S. Pat. No. 3,947,338 at column 2, line 65 to column 4, line 30, the portions of which are incorporated herein by reference).

By "blocked" is meant that the isocyanate groups have been reacted with a compound such that the resulting blocked isocyanate groups are stable to active hydrogen at ambient temperature, but react with active hydrogen in the film-forming polymer at elevated temperatures (such as between 90 ℃ and 200 ℃). The polyisocyanate curing agent may be a fully blocked polyisocyanate having substantially no free isocyanate groups.

The polyisocyanate curing agent may include a diisocyanate, a higher functional polyisocyanate, or a combination thereof. For example, the polyisocyanate curing agent may include aliphatic and/or aromatic polyisocyanates. The aliphatic polyisocyanates may include (i) alkylene isocyanates such as trimethylene diisocyanate, tetramethylene ethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate ("HDI"), 1, 2-propylene diisocyanate, 1, 2-butylene diisocyanate, 2, 3-butylene diisocyanate, 1, 3-butylene diisocyanate, ethylene diisocyanate, and butylene diisocyanate, and (ii) cycloalkylene isocyanates such as 1, 3-cyclopentane diisocyanate, 1, 4-cyclohexane diisocyanate, 1, 2-cyclohexane diisocyanate, isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate) ("HMDI"), cyclotrimers of 1, 6-hexamethylene diisocyanate (also known as the isocyanurate trimer of HDI, desmodur N3300 commercially available from Convestro AG), and m-tetramethylxylylene diisocyanate (commercially available from Allnex SA)

). The aromatic polyisocyanate may include (i) an arylene isocyanate such as m-phenylene diisocyanate, p-phenylene diisocyanate, 1, 5-naphthalene diisocyanate, and 1, 4-naphthalene diisocyanate, and (ii) an arylene isocyanate such as 4, 4' -diphenylene methane ("MDI"), 2, 4-toluene or 2, 6-toluene diisocyanate ("TDI"), or mixtures thereof, 4, 4-toluene diisocyanate, and xylene diisocyanate. Triisocyanates (such as triphenylmethane-4, 4', 4 "-triisocyanate, 1,3, 5-triisocyanate) can also be usedToluene and 2,4, 6-triisocyanate), tetraisocyanates (such as 4,4 ' -diphenyldimethylmethane-2, 2 ', 5,5 ' -tetraisocyanate), and polymeric polyisocyanates (such as toluene diisocyanate dimers and trimers), and the like.

The curing agent may include a blocked polyisocyanate selected from polymeric polyisocyanates such as polymeric HDI, polymeric MDI, polymeric isophorone diisocyanate, and the like. The curing agent may also include a blocked trimer of hexamethylene diisocyanate, commercially available from Covestro AG

Mixtures of polyisocyanate curing agents may also be used.

The polyisocyanate curing agent may be at least partially blocked by at least one blocking agent selected from the group consisting of: 1, 2-alkanediols (e.g., 1, 2-propanediol); 1, 3-alkanediols (e.g., 1, 3-butanediol); benzyl alcohol (e.g., benzyl alcohol); allyl alcohol (e.g., allyl alcohol); caprolactam; dialkylamines (e.g., dibutylamine); and mixtures thereof. The polyisocyanate curing agent may be at least partially blocked with at least one 1, 2-alkanediol having three or more carbon atoms (e.g., 1, 2-butanediol).

Other suitable blocking agents include aliphatic, cycloaliphatic, or aromatic alkyl monoalcohols or phenolic compounds, including, for example, lower (e.g., C)₁-C₆) Aliphatic alcohols such as methanol, ethanol, and n-butanol; alicyclic alcohols such as cyclohexanol; aromatic alkyl alcohols such as phenyl carbinol and methyl phenyl carbinol; and phenolic compounds such as phenol itself and substituents (wherein the substituents do not interfere with the coating operation), such as cresols and nitrophenols. 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 include an aminoplast resin. Aminoplast resins are condensation products of aldehydes with substances bearing amino or amide groups. Condensation products obtained by reacting alcohols and aldehydes with melamine, urea or benzoguanamine may be used. However, condensation products of other amines and amides may also be utilized, such as 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' -dimethylurea, benzourea, dicyandiamide, meglumine, acetoguanamine, anilide, 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 resin may comprise methylol groups or similar hydroxyalkyl groups, and at least a portion of these hydroxyalkyl groups may be etherified by reaction with an alcohol to provide an organic solvent soluble resin. Any monohydric alcohol may be utilized for this purpose, including alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and the like, as well as benzyl alcohol and other aromatic alcohols, cyclic alcohols (such as cyclohexanol), monoethers of glycols (such as cellosolve and carbitol), and halogen-substituted or otherwise substituted alcohols (such as 3-chloropropanol and butoxyethanol).

Non-limiting examples of commercially available aminoplast resins are trademarks available from Allnex Belgium SA/NV

Those obtained (such as CYMEL 1130 and 1156), and those available from INEOS Melamines

Those obtained (such as, for example, repree 750 and 753). Examples of suitable aminoplast resins also include those described in U.S. patent No. 3,937,679, column 16, line 3 to column 17, line 47, which is incorporated herein by reference. As disclosed in the aforementioned portion of the' 679 patent, the aminoplast may be used in combination with a hydroxymethylphenol ether.

Phenolic resins are formed by the condensation of aldehydes and phenols. Suitable aldehydes include formaldehyde and acetaldehyde. Methylene releasing and aldehyde releasing agents such as paraformaldehyde and hexamethylenetetramine may also be used as the aldehyde agent. Various phenols (such as phenol itself, cresol or substituted phenols) in which a hydrocarbon group having a linear, branched or cyclic structure is substituted for a hydrogen on an aromatic ring may be used. Mixtures of phenols may also be utilized. Some specific examples of suitable phenols are p-phenol, p-tert-butylphenol, p-tert-amylphenol, cyclopentylphenol, and unsaturated hydrocarbon-substituted phenols such as mono-butenylphenol containing butenyl groups in the ortho, meta, or para positions, with double bonds occurring at various positions in the hydrocarbon chain.

Aminoplasts and phenolic resins as described above are further described at column 6, line 20 to column 7, line 12 of U.S. patent No. 4,812,215, which is incorporated herein by reference.

The curing agent may be present in the cationic electrodepositable coating component 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 resin solids of the electrodepositable coating component. The curing agent may be present in the cationic electrodepositable coating component 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 resin solids of the electrodepositable coating component.

The curing agent may be present in the anionic electrodepositable coating component in an amount of at least 10% by weight, such as at least 20% by weight, such as at least 25% by weight, and 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 resin solids of the electrodepositable coating component. The curing agent may be present in the anionic electrodepositable coating component 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 resin solids of the electrodepositable coating component.

Alternatively, the electrodepositable coating composition according to the present invention may comprise one or more additional ingredients in addition to the film-forming binder described above.

Alternatively, according to the present invention, the electrodepositable coating composition may include a catalyst to catalyze the reaction between the curing agent and the polymer. Examples of suitable catalysts for the cationic electrodepositable coating composition include, but are not limited to, 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 cyclic guanidines, as described in U.S. patent No. 7,842,762, column 1, line 53 through column 4, line 18, and column 16, line 62 through column 19, line 8, the portions of the above documents being set forth herein by reference. Examples of suitable catalysts for the anionic electrodepositable coating composition include latent acid catalysts, specific examples of which are described in WO 2007/118024 No [0031 ]]Given in paragraph, including but not limited to ammonium hexafluoroantimonate, SbF₆The quaternary salt of (a) (e.g.,

XC-7231)、SbF₆the tertiary amine salt of (a) (e.g.,

XC-9223), zinc salt of trifluoromethanesulfonic acid (e.g.,

a202 and a218), quaternary salts of trifluoromethanesulfonic acid (e.g.,

XC-a230), and diethylamine salts of trifluoromethanesulfonic acid (e.g.,

A233) (all commercially available from King Industries), and/or mixtures thereof. Latent acid catalysts may be formed by preparing derivatives of the acid catalyst, such as p-toluene sulfonic 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 p-toluenesulfonate. Such sulfonates are less active than the free acid in promoting crosslinking. During curing, the catalyst may be activated by heating.

According to the present invention, the electrodepositable coating composition may further include other optional ingredients such as a pigment component and/or various additives including fillers, plasticizers, antioxidants, biocides, UV light absorbers and stabilizers, hindered amine light stabilizers, defoamers, fungicides, dispersion 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 optional ingredients, i.e., optional ingredients are not present in the electrodepositable coating composition. The pigment component may include, for example, iron oxide, lead oxide, strontium chromate, coal dust, titanium dioxide, talc, barium sulfate, and color pigments (such as cadmium yellow, cadmium red, chrome yellow, etc.). The pigment content of the pigment component excluding the above conductive particles may be expressed as a weight ratio of the pigment to the binder, and may be in the range of 0.03 to 0.1 when the pigment is used. The above-mentioned other additives may be present in the electrodepositable coating composition in an amount of 0.01 to 3% by weight, based on the total weight of the resin solids of the electrodepositable coating composition.

According to the present invention, the electrodepositable coating composition comprises an aqueous dispersion medium comprising water and/or one or more organic solvents. The water can be present in an amount of, for example, 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 electrodepositable coating composition. Examples of suitable organic solvents include oxygenated organic solvents such as ethylene glycol, diethylene glycol, propylene glycol, and monoalkyl ethers of dipropylene glycol, such as the monoethyl and monobutyl ethers of these glycols, containing from 1 to 10 carbon atoms in the alkyl group. Examples of other at least partially water-miscible solvents include alcohols such as ethanol, isopropanol, butanol, and diacetone alcohol. If used, the organic solvent may typically be present in an amount less than 10% by weight, such as less than 5% by weight, based on the total weight of the electrodepositable coating composition. The electrodepositable coating composition may be provided, inter alia, in the form of a dispersion, such as an aqueous dispersion.

According to the present invention, the total solid 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 not exceed 60% by weight, such as not exceed 40% by weight, such as not exceed 20% by weight, based on the total weight of the electrodepositable coating composition. The total solid 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 substrate

The present invention is also directed to a method of coating a substrate comprising electrophoretically applying to at least a portion of the substrate a coating deposited from an electrodepositable coating composition using the electrocoating system 10 described above.

The electrodepositable coating composition of the present invention may be deposited on an electrically conductive substrate by contacting the electrodepositable coating composition with an electrically conductive cathode and an electrically conductive anode, wherein the surface to be coated is either the anode or the cathode depending on the type of electrodepositable coating composition applied. After contact with the composition, an adherent film of the electrodepositable coating composition is deposited on the substrate when a sufficient voltage is applied between the electrodes by the power supply. The applied voltage may vary and can range, for example, from as low as one volt to as high as several thousand volts, such as between 25 volts and 600 volts. The current density may be between 0.5 and 15 amps per square foot.

Electrodepositable coating compositions useful in the process of the present invention may include any of those known in the art, including those described above. For example, the electrodepositable coating composition may include a cationic film-forming resin including sulfonium and/or ammonium groups, or the electrodepositable coating composition may include an anionic electrodepositable coating composition including carboxylic and/or phosphoric acid groups.

According to the present invention, the method can further comprise at least partially curing the electrophoretically applied coating deposited on the substrate from the electrodepositable coating composition. As discussed above, at least partially curing the electrodepositable coating composition may include subjecting the substrate to an elevated temperature.

For cationic electrodepositable coating compositions, the coated substrate can be heated to a temperature ranging from, for example, 250 ° F to 450 ° F (121.1 ℃ to 232.2 ℃), such as from 275 ° F to 400 ° F (135 ℃ to 204.4 ℃), such as from 300 ° F to 360 ° F (149 ℃ to 180 ℃). For anionic electrodepositable coating compositions, the coated substrate can be heated to a temperature ranging from, for example, 200 ° F to 450 ° F (93 ℃ to 232.2 ℃), such as from 275 ° F to 400 ° F (135 ℃ to 204.4 ℃), such as from 300 ° F to 360 ° F (149 ℃ to 180 ℃). The curing time may depend on the curing temperature as well as other variables, such as the film thickness of the electrodeposited coating, the level and type of catalyst present in the components, the type of curing agent employed, and the like. For the purposes of the present invention, all that is necessary is that time be sufficient to cure the coating on the substrate. For example, the curing time can be in the range of 10 minutes to 60 minutes, such as 20 to 40 minutes. For example, the thickness of the resulting cured electrodeposition coating may be in the range of 1 to 50 microns, such as 15 to 50 microns.

According to the present invention, a method of coating a substrate may comprise: (a) electrophoretically depositing a coating deposited from an electrodepositable coating composition onto at least a portion of a substrate using the electrocoating system 10 described above, and (b) heating the coated substrate to a temperature and for a time sufficient to at least partially cure the electrodeposited coating on the substrate. Optionally, according to the present invention, the method may further comprise: (c) applying one or more pigmented coating components and/or one or more non-pigmented coating components directly onto the at least partially cured electrodeposited coating to form an additional coating layer on at least a portion of the at least partially cured electrodeposited coating, and (d) curing the additional coating layer by allowing the additional coating layer to be at ambient temperature or by applying sufficient energy from an external energy source to the coated substrate of step (c) for conditions 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.

Optional additional coating layers may include one or more base coats and one or more suitable top coats (e.g., primer layers, clear coats, pigmented monocoats, and color-plus-clear composite components). It will be appreciated that suitable additional coatings include any of those known in the art, and each independently may be aqueous, solvent-borne, in solid particulate form (i.e., powder coating component), or in powder slurry form. Additional coating components may include a film-forming polymer, a cross-linking material, and, if a colored primer or monocoat, one or more pigments. Optionally, the one or more base coats may be disposed between the electrocoat layer and the one or more top coats. Alternatively, the one or more top coats may be omitted such that the composite includes an electrocoat layer and one or more primer layers.

Further, the one or more top coats can be applied directly onto the electrodepositable coating. In other words, the substrate may lack a primer layer such that the composite includes an electrocoat layer and one or more topcoats. For example, the primer layer can be applied directly onto at least a portion of the electrodepositable coating layer.

It will also be understood that any topcoat may be applied over the base layer, although the base layer is not fully cured. For example, the clear coat layer can be applied to the primer layer even if the primer layer has not undergone a curing step (wet-on-wet). The two layers can then be cured in a subsequent curing step, thereby eliminating the need to cure the primer layer and the clear coat layer separately.

Additional ingredients, such as colorants and fillers, may be present in the various coating components from which the top coat is derived according to the present invention. Any suitable colorants and fillers may be used. 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 coating of the present invention. It should be noted that, in general, the colorant can be present in the layers of the multilayer composite in any amount sufficient to impart the desired properties, visual and/or color effect.

Example colorants include pigments, dyes, and colorants (such as those used in the paint industry and/or in the Dry Color Manufacturer Association (DCMA)), as well as special effect components. The colorant may comprise, for example, a finely divided solid powder that is insoluble but wettable under the conditions of use. The colorant may be organic or inorganic, and may be agglomerated or non-agglomerated. The colorants can be incorporated into the coating by milling or simple mixing. The colorant can be incorporated by grinding the colorant into the coating using an abrasive, such as an acrylic abrasive, the use of which is familiar to those skilled in the art.

Exemplary pigments and/or pigment components include, but are not limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol AS, salt types (lakes), benzimidazolone, condensation, metal complexes, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perillyl ketone, diketopyrrolopyrrole, thioindigo, anthraquinone, indanthrone, anthrapyridine, human pyrimidine, flavanone, pyrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketopyrrolopyrrole red ("DPP red BO"), titanium dioxide, carbon black, zinc oxide, antimony oxide, and the like, AS well AS organic or inorganic ultraviolet opaque 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.

Exemplary dyes include, but are not limited to, those that are solvent and/or aqueous based, such as acid dyes, azo dyes, basic dyes, direct dyes, disperse dyes, reactive dyes, solvent dyes, sulfur dyes, mordant dyes, e.g., bismuth vanadate, anthraquinone, perylene, aluminum, quinacridone, thiazole, thiazine, azo, indigoid, nitro, nitroso, oxazine, phthalocyanine, quinoline, stilbene, and triphenylmethane.

Exemplary COLORANTS include, but are not limited to, pigments dispersed in an aqueous-based or water-miscible vehicle, such as AQEiA-CHEM 896 commercially available from Degussa, Inc., CHARISMA COLORANTS and MAXITONE 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 150nm (such as less than 70nm or less than 30 nm). Nanoparticles can be prepared by milling organic or inorganic pigments with milling media having a particle size of less than 0.5 mm. Exemplary nanoparticle dispersions and methods for making them are described in U.S. Pat. No. 6,875,800B2, 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). To minimize re-aggregation of the 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 are dispersed discrete "composite particles" that include nanoparticles and a resin coating on the nanoparticles. Exemplary dispersions of resin-coated nanoparticles and methods for their preparation are described in U.S. patent application No. 10/876,031 filed 24/6/2004, which is incorporated herein by reference, and U.S. provisional patent application No. 60/482,167 filed 24/6/2003, which is also incorporated herein by reference.

Special effect components that may be used in one or more layers of the multilayer coated composite according to the present invention include pigments and/or components that produce one or more appearance effects such as reflectance, pearlescence, metallic luster, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, goniochromism and/or color change. Additional special effect components may provide other perceptible properties such as reflectivity, opacity or texture. For example, special effect components can produce a color shift such that the color of the coating changes when the coating is viewed at different angles. Exemplary color effect components are described in U.S. Pat. No. 6,894,086, which is incorporated herein by reference. Additional color effect components may include transparent coated mica and/or synthetic mica, coated silica, coated alumina, transparent liquid crystal pigments, liquid crystal coatings, and/or any component in which interference is caused by refractive index differences within the material and not because of refractive index differences between the surface of the material and air.

According to the present invention, photosensitive components and/or photochromic components that reversibly change their color upon exposure to one or more light sources can be used in multiple layers in a multilayer composite. The photochromic and/or photosensitive components can be activated by exposure to radiation of a particular wavelength. When the component becomes active, the molecular structure changes, and the altered structure exhibits a new color that is different from the original color of the component. When the exposure to radiation is removed, the photochromic and/or photosensitive component can return to a resting state in which the component restores the original color. For example, the photochromic and/or photosensitive component may be colorless in the inactive state and may exhibit color in the excited state. A complete color change may occur in a time of milliseconds to several minutes, such as from 20 seconds to 60 seconds. Exemplary photochromic and/or photosensitive components include photochromic dyes.

The photosensitive component and/or photochromic component can be associated with and/or at least partially bound to the polymer and/or polymeric material of the polymerizable component, such as by covalent bonds. In contrast to certain coatings in which the photosensitive component may migrate out of the coating and crystallize into the substrate, in accordance with the present invention, the photosensitive component and/or photochromic component is associated with and/or at least partially bound to the polymer and/or polymerizable component, which minimally migrates out of the coating. Exemplary photoactive and/or photochromic components and methods for their preparation are described in U.S. patent application No. 10/892,919, filed 7, 16, 2004 and incorporated herein by reference.

Additional coatings may be applied by a topcoat system. The topcoat system can include any device and/or method known in the art for applying a topcoat coating composition. For example, the top coating system may include a device that applies a powder coating composition or a liquid coating composition. For example, the topcoat system can include a spray gun, a brush, a roller, a reservoir for dip coating, or a combination thereof. Optionally, the topcoat system may further comprise a spray booth, and the spray booth may optionally comprise a ventilation system.

As mentioned above, the coating composition may be a powder coating composition. As used herein, "powder coating component" refers to a coating component that is completely free of water and/or solvents. Accordingly, the powder coating components disclosed herein are not synonymous with water-based and/or solvent-based coating components known in the art.

According to the invention, the powder coating component comprises (a) a film-forming polymer having reactive functional groups; (b) a curing agent that reacts with the functional group. Examples of powder coating compositions that may be used in the present invention include polyester-based ENVIROROCN series 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 curing thermosetting powder coating compositions comprising: (a) at least one tertiary semicarbazide compound, at least one tertiary carbamate compound, or a mixture thereof, and (b) at least one film-forming epoxide-containing resin and/or at least one silicone-containing resin (such as those described in U.S. patent No. 7,470,752 assigned to PPG Industries, inc., which is incorporated herein by reference); curable powder coating compositions, typically comprising (a) at least one tertiary semicarbazide compound, at least one tertiary carbamate compound, or mixtures thereof, and (b) at least one film-forming epoxide-containing resin and/or at least one silicone-containing resin (such as those described in U.S. patent No. 7,432,333 assigned to PPG Industries, inc., which is incorporated herein by reference); and comprises a T having a temperature of at least 30 DEG C_gOf a solid particulate mixture of polymers containing reactive groups (such as those described in U.S. patent No. assigned to PPG Industries, inc6,797,387, which are incorporated herein by reference).

Suitable film-forming polymers that may be used in the powder coating component of the present invention include (poly) esters (e.g., polyester triglycidyl isocyanurate), (poly) urethanes, isocyanurates, (poly) ureas, (poly) epoxies, anhydrides, acrylics, (poly) ethers, (poly) sulfides, (poly) amines, (poly) amides, (poly) vinyl chlorides, (poly) olefins, (poly) vinylidene fluoride, or combinations thereof.

According to the present invention, the reactive functional groups of the film-forming polymer of the powder coating component include hydroxyl, carboxyl, isocyanate (including blocked (poly) isocyanates), primary amine, secondary amine, amide, carbamate, urea, urethane, vinyl, unsaturated ester, maleimide, fumarate, anhydride, hydroxyalkylamide, epoxy, or combinations thereof.

Suitable curing agents (crosslinkers) that may be used in the powder coating component of the present invention include aminoplast resins, polyisocyanates, blocked polyisocyanates, polyepoxides, polyacids, polyols, or combinations thereof.

After deposition of the powder coating components, the coating is often heated to cure the deposited components. The heating or curing operation is often carried out at a temperature of 150 ℃ to 200 ℃ (such as 170 ℃ to 190 ℃) for a time of 10 to 20 minutes. According to the invention, the thickness of the resulting film is 50 to 125 microns.

As mentioned above, the coating composition may be a liquid coating composition. As used herein, "liquid coating component" refers to a coating component that includes a portion of water and/or solvent. Accordingly, the liquid coating compositions disclosed herein are synonymous with water-based and/or solvent-based coating compositions known in the art.

According to the present invention, the liquid coating component may include, for example, (a) a film-forming polymer having reactive functional groups; (b) a curing agent that reacts with the functional group. In other examples, the liquid coating may comprise a film-forming polymer that can react with oxygen in the air or coalesce into a film as water and/or solvent evaporates. These film-forming mechanisms may require the application of heat or some type of radiation or fluxAccelerated by the application of heat or some type of radiation, such as ultraviolet or infrared. Examples of liquid coating compositions useful in the present invention include:

a series of solvent-based coating components,

A series of waterborne coating compositions, and

a series of UV curable 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 include (poly) esters, alkyds, (poly) urethanes, isocyanurates, (poly) ureas, (poly) epoxies, anhydrides, acrylics, (poly) ethers, (poly) sulfides, (poly) amines, (poly) amides, (poly) vinylchlorides, (poly) olefins, (poly) vinylidene fluorides, (poly) siloxanes, or combinations thereof.

In accordance with the present invention, the reactive functional groups of the film-forming polymer of the liquid coating component may include hydroxyl, carboxyl, isocyanate (including blocked (poly) isocyanates), primary amine, secondary amine, amide, carbamate, urea, carbamate, vinyl, unsaturated ester, maleimide, fumarate, anhydride, hydroxyalkylamide, epoxy, or combinations thereof.

Suitable curing agents (crosslinkers) that may be used in the liquid coating composition of the present invention may include aminoplast resins, polyisocyanates, blocked polyisocyanates, polyepoxides, polyacids, polyols, or combinations thereof.

Additionally, colorants can be included in the coating composition (electrodepositable, powdered, or liquid), as well as various additives (if desired), such as surfactants, wetting agents, or catalysts. As used herein, the term "colorant" means any substance that imparts color and/or other opacity and/or other visual effect to a component. The colorant can be added to the components 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 colorants (such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA)), as well as special effect components. The colorant may comprise, for example, a finely divided solid powder that is insoluble but wettable under the conditions of use. The colorant can be organic or inorganic, and can be agglomerated or non-agglomerated. The colorants can be incorporated by use of an abrasive tool, such as an acrylic abrasive tool, the use of which is familiar to those skilled in the art.

Exemplary pigments and/or pigment components include, but are not limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol AS, salt types (lakes), benzimidazolone, condensation, metal complexes, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perillyl ketone, diketopyrrolopyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanone, pyrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketopyrrolopyrrole red ("DPPBO red"), titanium dioxide, carbon black, and mixtures thereof. The terms "pigment" and "colored filler" can be used interchangeably.

Exemplary dyes include, but are not limited to, those that are solvent-borne and/or water-borne, such as phthalocyanine green or blue, iron oxide, bismuth vanadate, anthraquinone, perylene, aluminum, and quinacridone.

Exemplary COLORANTS include, but are not limited to, pigments dispersed in an aqueous or water-miscible vehicle such as AQUA-CHEM 896 commercially available from Degussa, inc, CHARISMA COLORANTS and MAXITONER inclusion COLORANTS commercially available from Accurate Dispersions department of Eastman Chemical, inc.

As mentioned 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 150nm, such as less than 70nm or less than 30 nm. Nanoparticles can be prepared by milling a stock organic or inorganic pigment with milling media having a particle size of less than 0.5 mm. Exemplary nanoparticle dispersions and methods for making them are described in U.S. Pat. No. 6,875,800B2, 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). To minimize re-aggregation of the 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 having dispersed therein discrete "composite particles" that include nanoparticles and a resin coating on the nanoparticles. Exemplary dispersions of resin-coated nanoparticles and methods for their preparation are described in U.S. patent application publication No. 2005-0287348a1, filed 24.6.2004, U.S. provisional patent application No. 60/482,167, filed 24.6.2003, and U.S. patent application No. 11/337,062, filed 20.1.2006, which are also incorporated herein by reference.

Example special effect components that may be used include pigments and/or components that produce one or more appearance effects, such as reflectance, pearlescence, metallic sheen, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, heterochromism, and/or color change. Additional special effect components can provide other perceptible properties, such as opacity or texture. According to the present invention, special effect components are capable of producing a color shift such that the color of the coating changes when the coating is viewed at different angles. Exemplary color effect components are described in U.S. Pat. No. 6,894,086, which is incorporated herein by reference. Additional color effect components can include transparent coated mica and/or synthetic mica, coated silica, coated alumina, transparent liquid crystal pigments, liquid crystal coatings, and/or any component in which interference is caused by refractive index differences within the material and not because of refractive index differences between the surface of the material and air.

According to the present invention, photosensitive components and/or photochromic components can be used that reversibly change their color when exposed to one or more light sources. The photochromic and/or photosensitive components can be activated by exposure to radiation of a particular wavelength. When the component becomes active, the molecular structure changes, and the altered structure exhibits a new color that is different from the original color of the component. When the exposure to radiation is removed, the photochromic and/or photosensitive component is able to return to a quiescent state in which the component restores its original color. According to the invention, the photochromic and/or photosensitive component can be colorless in the inactive state and exhibit color in the active state. A complete color change can occur in milliseconds to minutes, such as from 20 seconds to 60 seconds. Exemplary photochromic and/or photosensitive components include photochromic dyes.

According to the present invention, the photosensitive component and/or photochromic component can be associated with, and/or at least partially bound to, the polymer and/or polymeric material of the polymerizable component, such as by covalent bonds. In contrast to certain coatings in which the photosensitive component may migrate out of the coating and crystallize into the substrate, according to the present invention, the photosensitive component and/or photochromic component is associated with and/or at least partially bound to the polymer and/or polymerizable component, which minimally migrates out of the coating. Exemplary photoactive and/or photochromic components and methods for their preparation are described in U.S. patent application No. 10/892,919, filed 7, 16, 2004, which is incorporated herein by reference.

In general, the colorant can be present in the coating component in any amount sufficient to impart the desired visual and/or color effect. The colorant can comprise 1 to 65 weight percent, such as 3 to 40 weight percent or 5 to 35 weight percent, where weight percent is based on the total weight of the components.

Optionally, in accordance with the present invention, the method can further include pretreating the substrate with a pretreatment composition prior to applying the electrodepositable coating composition using the electrocoating system. As used herein, the term "pretreatment component" refers to a component that is capable of reacting with a substrate surface and chemically altering and combining with the substrate surface to form a film that provides corrosion protection. Non-limiting examples of pretreatment components include zinc phosphate pretreatment components, such as those described in U.S. Pat. nos. 4,793,867 and 5,588,989; zirconium-containing pretreatment components, such as those described in U.S. patent nos. 7,749,368 and 8,673,091; and so on. The pretreatment component can be contacted 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 rolling. According to the present invention, the temperature of the pretreatment component when applied to the substrate can be in the range of, for example, 40 ° F to 160 ° F (4.4 ℃ to 71.1 ℃), such as 60 ° F to 110 ° F (l5.6 ℃ to 43.3 ℃), such as 70 ° F to 90 ° F (2l.l ℃ to 32.2 ℃). For example, the pretreatment process may be performed at ambient or room temperature. The contact time is often 1 second to 15 minutes, such as 4 minutes to 10 minutes, such as 5 seconds to 4 minutes.

Alternatively, after contact with the pretreatment component, the substrate may be suitably dried, for example air dried at room temperature, or dried with hot air, for example by using an air knife, by flashing off water by briefly exposing the substrate to elevated temperatures, such as by drying the substrate in an oven at 15 ℃ to 100 ℃ (such as 20 ℃ to 90 ℃), or by drying the substrate in a heater means using, for example, infrared heat (such as standing at 70 ℃ for 10 minutes), or by passing the substrate between suction nip rollers. The substrate surface may be partially or, in some instances, completely dried prior to any subsequent contacting of the substrate surface with any water, solution, component, or the like. Optionally, in accordance with the present invention, after contact with the pretreatment components, the substrate may be rinsed (wet or dried) with an aqueous solution of tap water, deionized water, and/or a rinsing agent to remove any residue, and then optionally dried (e.g., air dried or hot air dried) as previously described. According to the invention, this water washing can be eliminated and the substrate (wet or suitably dried) can be contacted with subsequent treatment components.

The pretreatment components can be applied to the substrate by a pretreatment system. The pretreatment system can include a tank for immersion, a brush, a roller, a spray gun, or a combination thereof to apply the pretreatment components to the substrate. The pretreatment system can further include a tank, brush, roller, spray gun, or combination thereof for applying a cleaning component (such as water) to the substrate.

Optionally, in accordance with the present invention, the method can further comprise priming the substrate with a priming component prior to applying the electrodepositable coating composition using the electrocoating system. The basecoat component may be used alone or in combination with a pretreatment component or other treatment prior to application of the electrodepositable coating component. The base coating component may include a metal-rich coating component. As used herein, the term "metal-rich coating component" refers to a film-forming component comprising an organic or inorganic binder and at least 65% by weight of metal particles, based on the total solids weight of the coating component. As used herein, the term "metal particles" refers to elemental (i.e., zero valent) metal and metal alloy particles. As used herein, the term "particles" refers to materials in the form of particles (such as powders or dusts) as well as flakes, and can be in the form of any shape, such as spheres, ovals, cubes, rods, discs, prisms, and the like. The metal may include zinc, aluminum, or alloys thereof. The basecoat component may be contacted 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 rolling. It will be appreciated that the metal-rich primer coating can also be applied in a dry form, such as a powder or film. The metal-rich basecoat formed from the basecoat component can be applied to a dry film thickness of, for example, 2.5 to 500 microns.

After the undercoating component is applied to the substrate, the film formed on the surface of the substrate can be dried by driving the solvent out of the film by heating or by air drying time. Suitable drying conditions will depend on the particular basecoat composition and/or application, but an exemplary drying time of about 1 to 5 minutes at a temperature of about 60 to 250 ° F (15.6 to 12l ℃), such as 70 to 212 ° F (27 to 100 ℃), may be sufficient. More than one basecoat can be applied if desired. Between each coating, the previously applied coating may flash; that is, exposure to ambient conditions for a desired amount of time.

After the basecoat component is applied to the substrate, the applied basecoat component may be cured by any means known in the art. For example, the coating can be subjected to curing conditions sufficient to cure the basecoat component. For example, the coating composition may be subjected to curing conditions (such as ambient conditions) as discussed above, and for hours or days. Alternatively, the substrate may be subjected to curing conditions, such as radiation (e.g., UV radiation) or heating to a temperature and for a time sufficient to cure the basecoat coating.

The undercoating component can be applied to the substrate by an undercoating system. The base coating system can include a tank for immersion, a brush, a roller, a spray gun, or a combination thereof to apply the base coating component to the substrate. The base coating system can further include a tank, brush, roller, spray gun, or combination thereof for applying a cleaning component (such as water) to the substrate.

Alternatively, other treatments of the substrate may be performed prior to electrocoating in accordance with the invention. For example, the substrate may be cleaned, deoxidized, cleaned and deoxidized, anodized, acid washed, plasma treated, laser treated, or Ion Vapor Deposition (IVD) treated. At least a portion of the surface of the substrate can 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 cleaners well known to those skilled in the art. These optional treatments can be used alone or in combination with the pretreatment component and/or the base coat component.

The present invention is also directed to a substrate coated using the above electrocoating system. Alternatively, the substrate may be coated using a top coating system. Thus, the substrate comprises an electrocoat layer and optionally a topcoat layer.

As noted above, the present invention is also directed to a substrate coated using a pretreatment system and an electrocoating system. Alternatively, the substrate may be coated using a top coating system. Thus, the substrate includes a pretreatment layer, an electrocoat layer, and an optional topcoat layer.

As noted above, the present invention is also directed to a substrate coated using a primer coating system and an electrocoating system. Alternatively, the substrate may be coated using a top coating system. Thus, the substrate includes a primer layer, an electrocoat layer, and an optional topcoat layer.

The present invention is also directed to a substrate coated using the pretreatment system, the undercoating system, and the electrocoating system described above. Alternatively, the substrate may be coated using a top coating system. Thus, the substrate includes a pretreatment layer, a primer layer, an electrocoat layer, and an optional topcoat layer.

The present invention is also directed to a substrate coated according to the method of the present invention.

System for coating a substrate

The present invention is also directed to a system for coating a substrate, including a substrate of the electrocoating system described above. Optionally, the system for coating a substrate may further comprise a pretreatment system, a base coating system, a top coating system, or any combination thereof. For example, a system for coating a substrate may include a pretreatment system for pretreating the substrate; a priming system for priming a substrate; an electrocoating system for electrocoating a substrate; and a topcoat system for applying the topcoat coating to the substrate. The system for coating a substrate may include any combination of the systems discussed above applied sequentially. For example, a system for coating a substrate may include a pretreatment system followed by an electrocoating system; a system for coating a substrate may include a pretreatment system followed by an electrocoating system, and then a topcoat system; systems for coating a substrate may include a primer coating system followed by an electrocoat coating system; systems for coating a substrate may include a base coating system followed by an electrocoating system and then a top coating system; systems for coating a substrate may include a pretreatment system followed by a primer system, followed by an electrocoat system; systems for coating a substrate may include a pretreatment system followed by a base coating system, followed by an electrocoating system, followed by a topcoat system; or the system for coating the substrate may comprise an electrocoating system followed by a topcoat 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, except in any operating examples or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be understood 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 this 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 closed or open numerical ranges are described herein, all numbers, values, amounts, percentages, subranges, and fractions within or encompassed by the numerical ranges are to be considered as specifically included in and falling within the original disclosure of the present application, as if those numbers, values, amounts, percentages, subranges, and fractions were explicitly and completely written out.

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 deviation found in their respective testing measurements.

As used herein, unless otherwise indicated, plural terms can encompass their singular counterparts and vice versa, unless otherwise indicated. For example, although reference is made herein to "a" pump, "a" recirculation line, "a" return conduit, "an" inner electrode, and "an" outer electrode, combinations (i.e., multiple) of these components can be used. In addition, in this application, the use of "or" means "and/or" unless explicitly stated otherwise, even though "and/or" may be explicitly used in some instances.

As used herein, terms "comprising," "including," and the like, are to be understood in the context of this application as being synonymous with "comprising," and thus open-ended, and do not preclude the presence of additional unrecited or unrecited elements, materials, ingredients, or method steps. As used herein, in the context of the present application, "consisting of" is understood to exclude the presence of any unspecified element, ingredient or method step. As used herein, in the context of the present application, "consisting essentially of" is understood to include the elements, materials, ingredients, or method steps specified, as well as those that do not materially affect one or more of the basic and novel features of the described object.

As used herein, the terms "on … …", "onto … …", "applied on … …", "applied on … …", "formed on … …", "deposited on … …", "deposited on … …" refer to being formed, covered, deposited, or provided thereon, but not necessarily in contact with a surface. For example, an electrodepositable coating composition that is "deposited onto" a substrate does not preclude the presence of one or more other intermediate coating layers of the same or different composition located between the electrodepositable coating composition and the substrate.

While 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.

Aspects of the invention

In view of the foregoing, the present invention thus relates particularly, but not exclusively, to the following:

1. an electrocoating system for electrocoating a substrate, the system comprising: a tank configured to contain an electrodepositable coating composition; at least one pump in fluid communication with the tank; at least one return conduit connecting the tank with an inlet of the pump; at least one recirculation conduit comprising a first end in fluid communication with an outlet of the pump and a second end having at least one aperture, and comprising at least one external electrode positioned at least partially outside the tank, wherein:

the substrate has a first surface and a second surface;

the pump is configured to receive the electrodepositable coating composition from the return conduit and deliver the electrodepositable coating composition to the reservoir through the recirculation conduit;

the external electrode is configured to provide an electric charge to the electrodepositable coating composition; and

the recirculation conduit is configured to extend into the tank interior and position the aperture of the second end to deliver at least a portion of the charged electrodepositable coating composition to the first surface of the substrate.

2. The electrocoating system of aspect 1 in which the outer electrode includes at least 50% of the recirculation conduit.

3. The electrocoating system of aspect 1 or 2 in which the outer electrode has an inner surface configured to contact the electrodepositable coating composition, and the electrocoating system is configured such that the ratio of the total combined surface area of the outer electrode to the surface area of the first surface of the substrate based on the surface area of the outer surface region of the outer electrode is from 1:7 to 1: 1.

4. The electrocoating system of any of the preceding aspects in which the external electrode includes a portion of the recirculation conduit that is external to the tank.

5. The electrocoating system of any of the preceding aspects in which the second end of the recirculation conduit includes at least one nozzle that includes the orifice.

6. The electrocoating system of any one of the preceding aspects in which the second end of the recirculation conduit branches off and includes at least two orifices configured to deliver at least a portion of the electrodepositable coating composition charged by the external electrode to different surface portions of the first surface of the substrate.

7. The electrocoating system of any one of the preceding aspects in which the recirculation conduit includes a plurality of pores configured to deliver the electrodepositable coating composition charged by the external electrode to different portions of the first surface of the substrate.

8. The electrocoating system of any of aspects 1-5, wherein the electrocoating system includes a plurality of recirculation conduits configured to deliver the electrodepositable coating composition charged by the external electrode to different portions of the first surface of the substrate.

9. The electrocoating system of aspect 8 in which the plurality of recirculation pipes are positioned equidistantly along the length of the tank.

10. The electrocoating system of any of the preceding aspects, further comprising at least one internal electrode positioned inside the tank.

11. The electrocoating system of claim 10 in which the recirculation conduit includes a plurality of internal electrodes positioned along a length of the tank.

12. The electrocoating system of claim 11 in which the plurality of internal electrodes are positioned equidistantly along the length of the tank.

13. The electrocoating system of any of aspects 10-12, where the electrocoating system is configured such that a ratio of a total combined surface area of the inner electrodes to a surface area of the second surface of the substrate is 1:7 to 1: 1.

14. The electrocoating system of any of the preceding aspects, further comprising at least one power source for providing current to the electrocoating system.

15. The electrocoating system of aspect 14 in which the power supply is electrically coupled to the outer electrode, the inner electrode where present, and the substrate, in which the substrate includes the outer electrode and a counter electrode to the inner electrode where present.

16. The electrocoating system of claim 15 in which the electrical connection to the power source is such that the outer electrode and, where present, the inner electrode comprise an anode and the substrate comprises a cathode.

17. The electrocoating system of any of the preceding aspects in which the tank, the return conduit, the pump, and the recirculation conduit are directly coupled to form at least one continuous and uninterrupted loop configured for restricted flow of the electrodepositable coating composition through the return conduit, the pump, and the recirculation conduit.

18. The electrocoating system of any of the preceding aspects, in which the tank includes a base portion and at least one sidewall extending upwardly from the base portion.

19. The electrocoating system of any of the preceding aspects in which the substrate includes an open polygonal cross-sectional shape.

20. The electrocoating system of any of the preceding aspects in which the substrate includes a rectangular cross-sectional shape.

21. The electrocoating system of any of the preceding aspects in which the substrate is a shipping container.

22. The electrocoating system of any of the preceding aspects in which the substrate has at least 40m²Cross-sectional area of.

23. A method for coating a substrate comprising electrophoretically applying to at least a portion of the substrate a coating deposited with an electrodepositable coating composition using an electrocoating system according to any of the preceding aspects 1-18.

24. The method according to aspect 23, wherein the electrodepositable coating composition comprises a cationic film-forming resin containing sulfonium groups.

25. The method according to any one of aspects 23 or 24, wherein the method further comprises at least partially curing the electrodepositable coating composition.

26. The method of any of aspects 23-25, wherein the method further comprises applying a top coat coating composition to at least a portion of the substrate coated with the electrodepositable coating composition.

27. The method of any of aspects 23-26, wherein the method further comprises pretreating the substrate with a pretreatment component prior to applying the electrodepositable coating composition.

28. The method of any of aspects 23-27, wherein the method further comprises priming the substrate with a priming component prior to applying the electrodepositable coating composition.

29. The method of any of aspects 23-28, wherein the substrate comprises an open polygonal cross-sectional shape or a rectangular cross-sectional shape.

30. The method of any one of aspects 23-29, wherein the substrate is a shipping container.

31. The method according to any one of aspects 23-30, wherein the substrate has at least 40m²Cross-sectional area of.

32. A substrate coated by the method according to any one of the preceding aspects 23-31.

33. A system for coating a substrate comprising an electrocoating system according to any of aspects 1-22, and further comprising at least one of:

a pretreatment system for pretreating the substrate prior to treating the substrate in the electrocoating system;

a priming system for priming the substrate prior to treatment of the substrate in the electrocoating system; and/or

A topcoat system for applying a topcoat coating to the substrate after treating the substrate in the electrocoating system.

The following examples illustrate the invention, but should not be construed as limiting the invention to the details thereof. Unless otherwise indicated, all parts and percentages in the following examples, as well as throughout the specification, are by weight.

Prophetic examples

In this prophetic example, an intermodal container is coated using the system and method of the present invention. An intermodal container has four closed sides (the top or roof of the container, two side walls and one closed end), an opening at the opposite end covered by a door (which will open during electrodeposition), and a base that has a row of structural support members that run over the long sides of the container and is not closed. The structural support is the member used to attach and support the base of the finished container (the base is installed after painting). The open bag shape of the container makes it difficult to completely coat the inner surface of the container during electrodeposition using standard techniques (i.e., electrodes positioned along the inner wall of the tank). For the electrophoresis process to proceed efficiently (coating the entire interior surface of the container), the potential must be applied at a rate and voltage sufficient to initiate and sustain the electrodeposition process.

In order to apply a coating deposited from an electrodepositable coating composition to all surfaces of a container, the container must be completely immersed in an electrocoat bath that is large enough to be completely immersed in the container. For intermodal containers, the electrocoat bath may exceed 80,000 gallons of electrodepositable coating composition. The container can be lifted by a lifting device (e.g., a hoist or crane) through the four outside, top corners and positioned over the electrocoat bath. Once in the proper level, it is carefully lowered into the electrocoat bath during immersion and operated in a tank to minimize the formation of bubbles that may form in the container. It is contemplated that the electrodepositable coating composition may be contained at a temperature between 80 ° F and 95 ° F. Cooling may be required because the electrodeposition process should generate heat. In addition, anodes with films may be present in the electrocoat bath to remove acids also released during electrocoat deposition. It is necessary to accommodate the appropriate ratio of bare anode surface area to membrane area to provide the appropriate pH control for the bath. The calculation would need to include the inner surface of the outer electrode and the exposed outer surface area (if the outer electrode is an anode).

During electrodeposition, the external electrode will be charged in the same manner as a standard electrode, with the container electrically coupled to the other pole and acting as a counter electrode. The applied dc voltage may vary between 100V and 450V. The amperage will depend on the application rate of the coating, the immersion time, the coulombic efficiency of the specific electrodepositable coating composition, the application parameters, and the thickness of the application. For example, the anode of 316SS may have per ft²About 5 amps of effective capacitance. For cationic electrodeposition, the use of external anodes effectively doubles the effective surface area of each anode. Additionally, the charged electrodepositable coating composition flowing through the external anode and the recirculation conduit may carry or drive electrical energy to the cathode (i.e., container) at a greater distance than the stationary anode, wherein the electrodepositable coating composition contacts only the surface of the anode. Because of the limitations of standard electrocoating systems, this allows electrodepositable coating compositions to coat the interior of containers for which it is difficult to obtain sufficient projection force.

Those skilled in the art will appreciate that, in light of the foregoing disclosure, numerous modifications and variations can be made without departing from the broad inventive concept described and illustrated herein. Accordingly, it will be understood that the foregoing disclosure is only illustrative of various exemplary aspects of the present application and that numerous modifications and variations within the spirit and scope of the present application and appended claims may be readily made by those skilled in the art.

Claims

the substrate has a first surface and a second surface;

2. The electrocoating system of claim 1 in which the outer electrode comprises at least 50% of the recirculation conduit.

3. The electrocoating system of claim 1 wherein the outer electrode has an inner surface configured to contact the electrodepositable coating composition, and the electrocoating system is configured such that a ratio of a total combined surface area of the outer electrode based on a surface area of an outer surface region of the outer electrode to a surface area of the first surface of the substrate is 1:7 to 1: 1.

4. The electrocoating system of claim 1 in which the outer electrode includes a portion of the recirculation conduit that is outside the tank.

5. The electrocoating system of claim 1, wherein the second end of the recirculation conduit includes at least one nozzle that includes the orifice.

6. The electrocoating system of claim 1 wherein the second end of the recirculation conduit branches off and includes at least two orifices configured to deliver at least a portion of the electrodepositable coating composition charged by the external electrode to different surface portions of the first surface of the substrate.

7. The electrocoating system of claim 1, wherein the recirculation conduit includes a plurality of pores configured to deliver the electrodepositable coating composition charged by the external electrode to different portions of the first surface of the substrate.

8. The electrocoating system of claim 1, wherein the electrocoating system includes a plurality of recirculation conduits configured to deliver the electrodepositable coating composition charged by the external electrode to different portions of the first surface of the substrate.

9. The electrocoating system of claim 8, wherein the plurality of recirculation pipes are positioned equidistantly along a length of the tank.

10. The electrocoating system of claim 1 further comprising at least one internal electrode positioned inside the tank.

11. The electrocoating system of claim 10, wherein the recirculation conduit includes a plurality of internal electrodes positioned along a length of the tank.

12. The electrocoating system of claim 11, in which the plurality of internal electrodes are positioned equidistantly along a length of the tank.

13. The electrocoating system of claim 10, wherein the electrocoating system is configured such that a ratio of a total combined surface area of the inner electrodes to a surface area of the second surface of the substrate is 1:7 to 1: 1.

14. The electrocoating system of claim 1 further comprising at least one power supply for providing current to the electrocoating system, wherein the power supply is electrically coupled to the outer electrode and the substrate, wherein the substrate comprises a counter electrode to the outer electrode.

15. The electrocoating system of claim 10 further comprising at least one power supply for providing current to the electrocoating system, wherein the power supply is electrically coupled to the outer electrode, the inner electrode, and the substrate, wherein the substrate comprises a counter electrode to the inner electrode and the outer electrode.

16. The electrocoating system of claim 1 wherein the tank, the return conduit, the pump, and the recirculation conduit are directly coupled to form at least one continuous and uninterrupted loop configured for restricted flow of the electrodepositable coating composition through the return conduit, the pump, and the recirculation conduit.

17. The electrocoating system of claim 1 wherein the tank includes a base portion and at least one sidewall extending upwardly from the base portion.

18. The electrocoating system of claim 1 in which the substrate comprises an open-sided polygonal cross-sectional shape.

19. The electrocoating system of claim 1 in which the substrate comprises a rectangular cross-sectional shape.

20. The electrocoating system of claim 1 in which the substrate is a shipping container.

21. The electrocoating system of claim 1 in which the substrate has at least 40m²Cross-sectional area of.

22. A method for coating a substrate comprising electrophoretically applying to at least a portion of the substrate a coating deposited with an electrodepositable coating composition using the electrocoating system of claim 1.

23. The method of claim 22, wherein the electrodepositable coating composition comprises a cationic film-forming resin containing sulfonium groups.

24. The method of claim 22, wherein the method further comprises applying a top coat coating composition to at least a portion of the substrate coated with the coating deposited with the electrodepositable coating composition.

25. The method of claim 22, wherein the method further comprises pretreating the substrate with a pretreatment component prior to applying the coating deposited with the electrodepositable coating component.

26. The method of claim 22, wherein the method further comprises priming the substrate with a priming component prior to applying the coating deposited with the electrodepositable coating component.

27. The method of claim 22, wherein the substrate comprises an open polygonal cross-sectional shape or a rectangular cross-sectional shape.

28. The method of claim 22, wherein the substrate is a shipping container.

29. A substrate coated by the method of claim 22.

30. A system for coating a substrate comprising the electrocoating system of claim 1, and further comprising at least one of: