SYSTEMS AND METHOD FOR TREATING A SUBSTRATE

Abstract

Disclosed herein is a pretreatment composition comprising a Group IVB metal in an amount of 200 ppm to 5.000 ppm based on total weight of the pretreatment composition, total fluoride in an amount of 1.000 ppm to 25.000 ppm based on total weight of the pretreatment composition and an electropositive metal. Also disclosed herein is a pretreatment composition comprising a Group IVB metal in an amount greater than 500 ppm based on total weight of the pretreatment composition and free fluoride in an amount of 50 ppm to 750 ppm based on total weight of the pretreatment composition, wherein the pretreatment composition has a pHI greater than 4. Also disclosed herein are systems and methods for treating a substrate. Also disclosed herein are treated substrates.

Description

GOVERNMENT CONTRACT

This material is based upon work supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy under Cooperative Agreement DE-EE007756 entitled U.S. Automotive Materials Partnership Low-Cost Mg Sheet Component Development and Demonstration Project.

FIELD

The present disclosure relates to compositions, systems, and methods for treating a substrate.

BACKGROUND

The use of protective coatings on metal substrates for improved corrosion resistance and paint adhesion is common. Conventional techniques for coating such substrates include techniques that involve pretreating the metal substrate with chromium-containing compositions. The use of such chromate-containing compositions, however, imparts environmental and health concerns.

SUMMARY

Disclosed herein is a pretreatment composition comprising: a Group IVB metal present in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition; total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition; and copper.

Also disclosed herein is a pretreatment composition comprising: a Group IVB metal in an amount greater than 500 ppm based on total weight of the pretreatment composition; and free fluoride in an amount of 50 ppm to 750 ppm based on total weight of the pretreatment composition, wherein the pretreatment composition has a pH greater than 4.

Also disclosed herein is a method for treating a substrate, comprising contacting at least a portion of a surface of the substrate with any of the pretreatment compositions disclosed herein.

Also disclosed herein is a system for treating a substrate comprising: any of the pretreatment compositions disclosed herein; and a cleaner composition and/or a film-forming resin.

Also disclosed herein is a system for treating a substrate comprising: a first pretreatment composition comprising a Group IVB metal and free fluoride; and a second pretreatment composition comprising a Group IVB metal present in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition, total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition, and an electropositive metal.

Also disclosed herein is a substrate comprising a film formed on at least a portion thereof, wherein the film is formed from any of the pretreatment compositions disclosed herein.

DETAILED DESCRIPTION

For purposes of the following detailed description, it is to be understood that the disclosure may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be read as if prefaced by the word “about.” even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open-ended numerical range is described herein, all numbers, values, amounts, percentages, subranges and fractions within or encompassed by the numerical range are to be considered as being specifically included in and belonging to the original disclosure of this application as if these numbers, values, amounts, percentages, subranges and fractions had been explicitly written out in their entirety.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

As used herein, unless indicated otherwise, a plural term can encompass its singular counterpart and vice versa, unless indicated otherwise. For example, although reference is made herein to “a” Group IVB metal” and “an” electropositive metal, a combination (i.e., a plurality) of these components can be used.

In addition, in this application, the use of “or” means “and/or” unless specifically stated otherwise, even though “and/or” may be explicitly used in certain circumstances.

As used herein, “including.” “containing” and like terms are understood in the context of this application to be synonymous with “comprising” and are therefore open-ended and do not exclude the presence of additional undescribed or unrecited elements, materials, ingredients or method steps. As used herein “consisting of” is understood in the context of this application to exclude the presence of any unspecified element, ingredient, or method step. As used herein, “consisting essentially of” is understood in the context of this application to include the specified elements, materials, ingredients or method steps “and those that do not materially affect the basic and novel characteristic(s)” of what is being described.

As used herein, the terms “on,” “onto,” “applied on,” “applied onto,” “formed on,” “deposited on,” “deposited onto,” means formed, overlaid, deposited, or provided on but not necessarily in contact with the surface. For example, a coating composition “applied onto” a substrate does not preclude the presence of one or more other intervening coating layers of the same or different composition located between the coating composition and the substrate.

As used herein, “coating composition” refers to a composition, e.g., a solution, mixture, or a dispersion, that, in an at least partially dried or cured state, is capable of producing a film, layer, or the like on at least a portion of a substrate surface.

As used herein, a “system” refers to a plurality of treatment compositions (including cleaners and rinses) used to treat a substrate and to produce a treated substrate. The system can be part of a production line (such as a factory production line) that produces a finished substrate or a treated substrate that is suitable for use in other production lines.

As used herein, “salt” refers to an ionic compound made up of metal or non-metal cations and non-metallic anions and having an overall electrical charge of zero. Salts may be hydrated or anhydrous.

As used herein, “aqueous composition” or “aqueous coating composition” refers to a solution or dispersion in a medium that comprises predominately water. For example, the aqueous composition may comprise water in an amount of more than 50 wt. %, or more than 70 wt. %, or more than 80 wt. %, or more than 90 wt. %, or more than 95 wt. % based on the total weight of the composition. That is, the aqueous composition may for example consist substantially of water.

As used herein, the term “dispersion” refers to a two-phase transparent, translucent or opaque system in which non-soluble particles are in the dispersed phase and an aqueous medium, which includes water, is in the continuous phase.

As used herein, the terms “Group IA metal” and “Group IA element” refer to an element that is in Group IA of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^rd edition (1983), corresponding to Group 1 in the actual IUPAC numbering.

As used herein, the term “Group IA metal compound” refers to a metal compound that includes at least one element that is in Group IA of the CAS version of the Periodic Table of the Elements.

As used herein, the terms “Group IIIB metal” and “Group IIIB element” refer to an element that is in Group IIIB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^rd edition (1983), corresponding to Group 3 in the actual IUPAC numbering.

As used herein, the term “Group IIIB metal compound” refers to a compound that includes at least one element that is in Group IIIB of the CAS version of the Periodic Table of the Elements.

As used herein, the terms “Group IVB metal” and “Group IVB element” refer to an element that is in Group IVB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^rd edition (1983), corresponding to Group 4 in the actual IUPAC numbering.

As used herein, the term “Group IVB metal compound” refers to a compound that includes at least one element that is in Group IVB of the CAS version of the Periodic Table of the Elements.

As used herein, the terms “Group VIB metal” and “Group VIB element” refer to an element that is in Group VIB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^rd edition (1983), corresponding to Group 6 in the actual IUPAC numbering.

As used herein, the term “Group VIB metal compound” refers to a compound that includes at least one element that is in Group VIB of the CAS version of the Periodic Table of the Elements.

As used herein, “pretreatment composition” refers to a composition that is capable of reacting with and chemically altering the substrate surface and binding to it to form a film that affords corrosion protection. The pretreatment composition may be an aqueous composition.

As used herein, “pretreatment bath” refers to a bath containing the pretreatment composition and that may contain components that are byproducts of the process.

As used herein, “atomic %” or “atomic percent” means the percentage of one kind of atom relative to the total number of atoms on or in the treated substrate as measured by x-ray fluorescence (“XRF”).

As further defined herein, ambient conditions generally refer to room temperature and humidity conditions or temperature and humidity conditions that are typically found in the area in which the composition is being applied to a substrate, e.g., at 10° C. to 40° C. and 4% to 80% relative humidity, while slightly thermal conditions are temperatures that are slightly above ambient temperature. As used herein, “slightly thermal conditions” are temperatures that range from 32° C. to 40° C.

As used herein, unless indicated otherwise, the term “substantially free” means that a particular material is present in a mixture or a composition (or a coating, film, or layer formed therefrom) in an amount of less than 5 parts per million (ppm) based on total weight of the mixture or composition (or coating, film, or layer formed therefrom). As used herein, unless indicated otherwise, the term “essentially free” means that a particular material is present in a mixture or a composition (or a coating, film or layer formed therefrom) in an amount of less than 1 ppm based on total weight of the mixture or composition (or coating, film, or layer formed therefrom). As used herein, unless indicated otherwise, the term “completely free” means that a particular material is present in a mixture or a composition (or a coating, film or layer formed therefrom) in an amount of less than 1 part per billion (ppb) based on total weight of the mixture or composition (or coating, film or layer formed therefrom) in an amount of less than 1 part per billion (ppb) based on total weight of the mixture or composition (or coating, film, or layer formed therefrom) or that such material is below the detection limit of common analytical techniques. When a mixture or a composition (or a coating, film, or layer formed therefrom) is substantially free, essentially free, or completely free of a particular material, this means that such material in any form is excluded from the mixture or composition (or coating, film, or layer formed therefrom), except that such material may unintentionally be present as a result of, for example, carry-over from prior treatment baths in the processing line, contamination from a substrate, or the like.

Unless otherwise disclosed herein, as used herein, the terms “total composition weight.” “total weight of a composition” or similar terms refer to the total weight of all ingredients being present in the respective composition including any carriers and solvents.

As mentioned above, the present disclosure is directed to a pretreatment composition comprising, consisting essentially of, or consisting of a Group IVB metal present in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition; total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition; and copper.

The present disclosure also is directed to a pretreatment composition comprising, consisting essentially of, or consisting of a Group IVB metal present in an amount greater than 500 ppm based on total weight of the pretreatment composition and free fluoride in an amount of 50 ppm to 750 ppm based on total weight of the pretreatment composition, wherein the pretreatment composition has a pH greater than 4.

As stated above, the pretreatment composition may comprise a Group IVB metal. The Group IVB metal may comprise zirconium, titanium, hafnium, or combinations thereof. The Group IVB metal may be provided in the form of an acid or a salt. For example, the Group IVB metal may be a compound of zirconium, titanium, hafnium, or a mixture thereof. Suitable compounds of zirconium include, but are not limited to, hexafluorozirconic acid, alkali metal and ammonium salts thereof, zirconium tetrafluoride, ammonium zirconium carbonate, zirconium carboxylates and zirconium hydroxy carboxylates, such as zirconium acetate, zirconium oxalate, ammonium zirconium glycolate, ammonium zirconium lactate, ammonium zirconium citrate, zirconium basic carbonate, zirconyl nitrate, zirconyl sulfate, oxides or hydroxides of zirconium, and mixtures thereof. Suitable compounds of titanium include, but are not limited to, hexafluorotitanic acid, fluorotitanic acid and salts thereof. A suitable compound of hafnium includes, but is not limited to, hafnium nitrate.

The Group IVB metal may be present in the pretreatment composition in an amount of at least 200 ppm based on total weight of the pretreatment composition, such as at least 250 ppm, such as at least 300 ppm, such as at least 500 ppm, such as at least 600 ppm, such as at least 700 ppm, such as at least 800 ppm, such as at least 900 ppm. The Group IVB metal may be present in the pretreatment composition in an amount of no more than 5,000 ppm based on total weight of the pretreatment composition, such as no more than 4,000 ppm, such as no more than 3,000 ppm, such as no more than 2,000 ppm, such as no more than 1,500 ppm. The Group IVB metal may be present in the pretreatment composition in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition, such as 250 ppm to 4,000 ppm, such as 300 ppm to 3,000 ppm, such as 500 ppm to 2,000 ppm, such as such as 500 ppm to 5,000 ppm, such as 600 ppm to 4,000 ppm, such as 700 ppm to 3,000 ppm, such as 800 ppm to 2,000 ppm, such as 900 ppm to 1,500 ppm.

The pretreatment composition may comprise fluoride. Fluoride may be measured as total fluoride, which comprises both free fluoride and bound fluoride. As used herein, “free fluoride” means fluoride that is present in the pretreatment composition that is not bound to metal ions or hydrogen ions. As used herein, “bound fluoride” means fluoride that comprises fluoride anions in solution that are ionically or covalently bound to metal cations or hydrogen ions. The fluoride ions thus complexed are not measurable with a fluoride ion selective electrode (ISE) unless the solution they are present in is mixed with an ionic strength adjustment buffer (e.g., citrate anion or EDTA) that releases the fluoride ions from such complexes, at which point the fluoride ions are measurable by the fluoride ISE, and the measurement is known as “total fluoride.” Alternatively, the total fluoride can be calculated by comparing the weight of the fluoride supplied in the conversion composition by the total weight of the conversion composition.

In examples, free fluoride may be measured as an operational parameter in the pretreatment composition bath using, for example, an Orion Dual Star Dual Channel Benchtop Meter equipped with a fluoride ion selective electrode (“ISE”) available from Thermoscientific, the symphony® Fluoride Ion Selective Combination Electrode supplied by VWR International, or similar electrodes. See, e.g., Light and Cappuccino, Determination of fluoride in toothpaste using an ion-selective electrode, J. Chem. Educ., 52:4, 247-50, April 1975. The fluoride ISE may be standardized by immersing the electrode into solutions of known fluoride concentration and recording the reading in millivolts, and then plotting these millivolt readings in a logarithmic graph. The millivolt reading of an unknown sample can then be compared to this calibration graph and the concentration of fluoride determined. Alternatively, the fluoride ISE can be used with a meter that will perform the calibration calculations internally and thus, after calibration, the concentration of the unknown sample can be read directly.

Free fluoride in the pretreatment composition may be derived from Group IVB metals present in the pretreatment composition, including, for example, hexafluorozirconic acid or hexafluorotitanic acid. Additionally, other complex fluorides, such as H₂SiF₆, KHF₂ or HBF₄, can be added to the pretreatment composition to supply free fluoride. The skilled artisan will understand that the presence of free fluoride in the pretreatment bath can impact pretreatment deposition and etching of the substrate, hence it is critical to measure this bath parameter. The levels of free fluoride will depend on the pH and the addition of chelators into the pretreatment bath and indicates the degree of fluoride association with the metal ions/protons present in the pretreatment bath.

The total fluoride of the pretreatment composition may be present in an amount of at least 1,000 ppm based on total weight of the pretreatment composition, such as at least 1,500 ppm, such as at least 2,000 ppm. The total fluoride of the pretreatment composition may be present in an amount of no more than 25,000 ppm based on total weight of the pretreatment composition, such as no more than 20,000 ppm, such as no more than 15,000 ppm, such as no more than 10,000 ppm, such as no more than 5,000 ppm, such as no more than 3,000 ppm. The total fluoride of the pretreatment composition may be present in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition, such as 1,000 ppm to 5,000 ppm, such as 1,000 ppm to 3,000 ppm, such as 1,500 ppm to 20,000 ppm, such as 1,500 ppm to 5,000 ppm, such as 1,500 ppm to 3,000 ppm, such as 2,000 ppm to 15,000 ppm, such as 2,000 ppm to 5,000 ppm, such as 2,000 ppm to 3,000 ppm.

The free fluoride of the pretreatment bath may be present in an amount of at least 50 ppm based upon total weight of the pretreatment composition, such as at least 60 ppm, such as at least 70 ppm. The free fluoride of the pretreatment bath may be present in an amount of no more than 750 ppm based upon total weight of the pretreatment composition, such as no more than 600 ppm, such as no more than 500 ppm. The free fluoride of the pretreatment bath may be present in an amount from 50 ppm to 750 ppm based upon total weight of the pretreatment composition, such as 60 ppm to 600 ppm, such as 70 ppm to 500 ppm.

The pretreatment composition may also comprise an electropositive metal. As used herein, “electropositive metal” refers to metals that are more electropositive than the metal substrate. This means that, for purposes of the present disclosure, the term “electropositive metal” encompasses metals that are less easily oxidized than the metal of the metal substrate that is being treated. As will be appreciated by those skilled in the art, the tendency of a metal to be oxidized is called the oxidation potential, is expressed in volts, and is measured relative to a standard hydrogen electrode, which is arbitrarily assigned an oxidation potential of zero. The oxidation potential for several elements is set forth in Table 1 below. An element is less easily oxidized than another element if it has a voltage value, E*, in the following table, that is greater than the element to which it is being compared.

	TABLE 1
	Element	Half-cell reaction	Voltage, E*
	Potassium	K+ + e → K	−2.93
	Calcium	Ca2+ + 2e → Ca	−2.87
	Sodium	Na+ + e → Na	−2.71
	Magnesium	Mg2+ + 2e → Mg	−2.37
	Aluminum	Al3+ + 3e → Al	−1.66
	Zinc	Zn2+ + 2e → Zn	−0.76
	Iron	Fe2+ + 2e → Fe	−0.44
	Nickel	Ni2+ + 2e → Ni	−0.25
	Tin	Sn2+ + 2e → Sn	−0.14
	Lead	Pb2+ + 2e → Pb	−0.13

Metal substrates that may be used in the present disclosure include, but are not limited to, cold rolled steel, hot rolled steel, steel coated with zinc metal, zinc compounds, or zinc alloys, hot-dipped galvanized steel, galvannealed steel, steel plated with zinc alloy, aluminum alloys, aluminum plated steel, aluminum alloy plated steel, magnesium and magnesium alloys. Suitable electropositive metal ions for deposition thereon include, for example, nickel, copper, silver, and gold, as well as mixtures thereof.

When the electropositive metal ion comprises copper, both soluble and insoluble compounds may serve as a source of copper ions in the pretreatment composition. For example, the supplying source of copper ions in the pretreatment composition may be a water-soluble copper compound. Specific examples of such compounds include, but are not limited to, copper sulfate, copper nitrate, copper thiocyanate, disodium copper ethylenediaminetetraacetate tetrahydrate, copper bromide, copper oxide, copper hydroxide, copper chloride, copper fluoride, copper gluconate, copper citrate, copper lauroyl sarcosinate, copper lactate, copper oxalate, copper tartrate, copper malate, copper succinate, copper malonate, copper maleate, copper benzoate, copper salicylate, copper amino acid complexes, copper fumarate, copper glycerophosphate, sodium copper chlorophyllin, copper fluorosilicate, copper fluoroborate and copper iodate, as well as copper salts of carboxylic acids such as in the homologous series formic acid to decanoic acid, and copper salts of polybasic acids in the series oxalic acid to suberic acid.

When copper ions supplied from such a water-soluble copper compound are precipitated as an impurity in the form of copper sulfate, copper oxide, etc., it may be desirable to add a complexing agent that suppresses the precipitation of copper ions, thus stabilizing them as a copper complex in the composition.

The copper compound may be added as a copper complex salt such as K3Cu (CN) 4 or Cu-EDTA, which can be present stably in the pretreatment composition on its own, but it is also possible to form a copper complex that can be present stably in the pretreatment composition by combining a complexing agent with a compound that is difficult to solubilize on its own. Examples thereof include a copper cyanide complex formed by a combination of CuCN and KCN or a combination of CuSCN and KSCN or KCN, and a Cu-EDTA complex formed by a combination of CuSO₄ and EDTA·2Na.

The composition may comprise copper. In examples, the composition may be substantially free, essentially free, or completely free of any electropositive metal other than copper.

It has been surprisingly discovered that inclusion of copper to a pretreatment composition comprising a Group IVB metal and fluoride increases deposition of zirconium and fluoride and improves corrosion protection on a steel substrate compared to a pretreatment composition without copper, while maintaining performance on a magnesium substrate. It has also been surprisingly discovered a pretreatment composition comprising a Group IVB metal and free fluoride with a pH of at least 4 results in a significant deposition of zirconium on steel substrates and magnesium substrates, and results in excellent corrosion performance on aluminum substrates, steel substrates, and magnesium substrates. Therefore, it has been surprisingly discovered that the pretreatment compositions of the present disclosure provide excellent corrosion protection for multi-metal articles.

The electropositive metal ion may be present in the pretreatment composition in an amount of at least 2 ppm based on the total weight of the pretreatment composition, such as at least 10 ppm, such as at least 20 ppm. The electropositive metal ion may be present in the pretreatment composition in an amount of no more than 200 ppm based on the total weight of the pretreatment composition, such as no more than 100 ppm, such as no more than 75 ppm, such as no more than 40 ppm. The electropositive metal ion may be present in the pretreatment composition in an amount of from 2 ppm to 200 ppm based on the total weight of the pretreatment composition, such as from 2 ppm to 75 ppm, such as from 10 ppm to 100 ppm, such as from 20 ppm to 75 ppm, such as 20 ppm to 40 ppm.

The pretreatment composition also may comprise lithium. The source of lithium metal in the pretreatment composition may be in the form of a salt. Non-limiting examples of suitable lithium salts include lithium nitrate, lithium sulfate, lithium fluoride, lithium chloride, lithium hydroxide, lithium carbonate, lithium iodide, and combinations thereof.

The lithium may be present in the pretreatment composition in an amount of at least 2 ppm based on total weight of the pretreatment composition, such as at least 5 ppm, such as at least 25 ppm, such as at least 75 ppm. The lithium may be present in the pretreatment composition in an amount of no more than 500 ppm based on total weight of the pretreatment composition, such as no more than 250 ppm, such as no more than 125 ppm, such as no more than 100 ppm. The lithium may be present in the pretreatment composition in an amount of 2 ppm to 500 ppm based on total weight of the pretreatment composition, such as 5 ppm to 250 ppm, such as 25 ppm to 125 ppm, such as 75 ppm to 100 ppm.

The pretreatment composition may also comprise molybdenum. The source of molybdenum in the pretreatment composition may be in the form of a salt. Non-limiting examples of suitable molybdenum salts include sodium molybdate, lithium molybdate, calcium molybdate, potassium molybdate, ammonium molybdate, molybdenum chloride, molybdenum acetate, molybdenum sulfamate, molybdenum formate, molybdenum lactate, and combinations thereof.

The molybdenum may be present in the pretreatment composition in an amount of at least 5 ppm based on total weight of the pretreatment composition, such as at least 25 ppm, such as at least 100 ppm. The molybdenum may be present in the pretreatment composition in an amount of no more than 500 ppm based on total weight of the pretreatment composition, such as no more than 250 ppm, such as no more than 150 ppm. The molybdenum may be present in the pretreatment composition in an amount of 5 ppm to 500 ppm based on total weight of the pretreatment composition, such as 25 ppm to 250 ppm, such as 100 ppm to 150 ppm.

The pretreatment composition may comprise a Group IIIB metal. The Group IIIB metal may comprise yttrium. A suitable compound of yttrium includes, but is not limited to, yttrium nitrate, yttrium chloride, yttrium bromide, methylsulfonic acid yttrium complex or combinations thereof.

The Group IIIB metal may be present in the pretreatment composition in an amount of at least 10 ppm based on total weight of the pretreatment composition, such as at least 50 ppm based on total weight of the pretreatment composition, such as at least 100 ppm, such as at least 500 ppm, such as at least 700 ppm. The Group IIIB metal may be present in the pretreatment composition in an amount of no more than 5,000 ppm based on total weight of the pretreatment composition, such as no more than 4,000 ppm, such as no more than 3,000 ppm. The Group IIIB metal may be present in the pretreatment composition in an amount of from 10 ppm to 5,000 ppm, such as 50 ppm to 4,000 ppm, such as 500 ppm to 3,000 ppm, such as 700 ppm to 3,000 ppm.

Optionally, the pretreatment composition may be substantially free, essentially free, or completely free of a third metal. By way of nonlimiting example, the composition may be substantially free, essentially free, or completely free of aluminum, calcium, magnesium, boron, zinc, iron, manganese and/or tungsten. The composition may be substantially free, essentially free, or completely free of aluminum. The composition may be substantially free, essentially free, or completely free of calcium. The composition may be substantially free, essentially free, or completely free of magnesium. The composition may be substantially free, essentially free, or completely free of boron. The composition may be substantially free, essentially free, or completely free of zinc. The composition may be substantially free, essentially free, or completely free of iron. The composition may be substantially free, essentially free, or completely free of manganese. The composition may be substantially free, essentially free, or completely free of tungsten.

The pretreatment composition may comprise a pH of at least 1.0, such as at least 1.5, such as at least 2.0, such as at least 3.0, such as at least 3.5, such as at least 4.0. The pretreatment composition may comprise a pH of no more than 6.0, such as no more than 5.5, such as no more than 5.0, such as no more than 4.5, such as no more than 3.5. The pretreatment composition may comprise a pH of 1.0 to 6.0, such as 2.0 to 5.0, such as 3.0 to 5.0, such as 1.0 to 5.0, such as 1.5 to 4.5, such as 2.0 to 3.5, such as 4.0 to 6.0, such as 4.0 to 5.5, such as 4.0 to 5.0. The pH may be adjusted using, for example, any acid and/or base as is necessary. The pH of the pretreatment composition may be maintained through the inclusion of an acidic material, including water soluble and/or water dispersible acids, such as nitric acid, sulfuric acid, and/or phosphoric acid. The pH of the composition may be maintained through the inclusion of a basic material, including water soluble and/or water dispersible bases, such as sodium hydroxide, sodium carbonate, potassium hydroxide, ammonium hydroxide, ammonia, and/or amines such as triethylamine, methylethyl amine, or mixtures thereof.

The pretreatment composition may, in some instances, exclude phosphate ions or phosphate-containing compounds and/or the formation of sludge, such as aluminum phosphate, iron phosphate, and/or zinc phosphate, formed in the case of using a treating agent based on zinc phosphate. As used herein, “phosphate-containing compounds” include compounds containing the element phosphorous such as orthophosphate, pyrophosphate, metaphosphate, tripolyphosphate, organophosphonates, and the like, and can include, but are not limited to, monovalent, divalent, or trivalent cations such as: sodium, potassium, calcium, zinc, nickel, manganese, aluminum, and/or iron. When a composition and/or a material deposited on a substrate surface by deposition of the pretreatment composition is substantially free, essentially free, or completely free of phosphate, this includes phosphate ions or compounds containing phosphate in any form.

Thus, the pretreatment composition and/or a material deposited on a substrate surface by deposition of the pretreatment composition may be substantially free, or in some cases may be essentially free, or in some cases may be completely free, of one or more of any of the ions or compounds listed in the preceding paragraph. A pretreatment composition and/or deposited material that is substantially free of phosphate means that phosphate ions or compounds containing phosphate are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the composition. This may further include that phosphate is not present in the pretreatment composition and/or deposited materials in such a level that they cause a burden on the environment. The term “substantially free” means that the pretreatment composition and/or deposited material contains less than 5 ppm of any or all the phosphate anions or compounds listed in the preceding paragraph based on total weight of the composition or the deposited material, respectively, if any at all. The term “essentially free” means that the first pretreatment compositions and/or deposited material contains less than 1 ppm of any or all the phosphate anions or compounds listed in the preceding paragraph. The term “completely free” means that the first pretreatment composition and/or deposited material contain less than 1 ppb of any or all the phosphate anions or compounds listed in the preceding paragraph, if any at all.

The pretreatment composition may exclude chromium or chromium-containing compounds. That is, the pretreatment composition and/or coatings or layers deposited from the pretreatment composition may be substantially free, may be essentially free, and/or may be completely free of such chromium or chromium-containing compounds. As used herein, the term “chromium-containing compound” refers to materials that include trivalent and/or hexavalent chromium. Non-limiting examples of such materials include chromic acid, chromium trioxide, chromic acid anhydride, dichromate salts, such as ammonium dichromate, sodium dichromate, potassium dichromate, and calcium, barium, magnesium, zinc, cadmium, strontium dichromate, chromium (III) sulfate, chromium (III) chloride, and chromium (III) nitrate. When a pretreatment composition or a material deposited onto a substrate surface by deposition of the pretreatment composition is substantially free, essentially free, or completely free of chromium, this includes chromium in any form, such as, but not limited to, the trivalent and hexavalent chromium-containing compounds listed above.

Thus, optionally, the pretreatment compositions and/or material deposited on a substrate surface by deposition of the pretreatment composition may be substantially free, may be essentially free, and/or may be completely free of one or more of any of the elements or compounds in the preceding paragraph. A pretreatment composition or a material deposited on a substrate surface by deposition of the pretreatment composition that is substantially free of chromium or derivates thereof means that chromium or derivatives thereof are not intentionally added, but may be present in trace amount, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the pretreatment composition or deposited material. In the case of chromium, this may further include that the element or compounds thereof are not present in the pretreatment compositions and/or deposited material in such a level that it causes a burden on the environment. The term “substantially free” means that the pretreatment composition and/or deposited material contains less than 10 ppm of any or all the elements or compounds listed in the preceding paragraph based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the pretreatment compositions and/or deposited material contains less than 1 ppm of any or all the elements or compounds listed in the preceding paragraph, if any at all. The term “completely free” means that the pretreatment composition comprises 0 ppm of such material or that such material is below the detection limit of common analytical techniques.

The pretreatment composition may be substantially free, essentially free, or

completely free of organic compounds.

The pretreatment composition may comprise an aqueous medium and may optionally contain other materials such as nonionic surfactants and auxiliaries conventionally used in the art of pretreatment compositions. In the aqueous composition, water dispersible organic solvents, for example, alcohols with up to about 8 carbon atoms such as methanol, isopropanol, and the like, may be present, or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol, or propylene glycol, and the like. When present, water dispersible organic solvents are typically used in amounts up to about ten percent by volume, based on the total volume of aqueous composition.

The pretreatment composition also may comprise a resinous binder. Suitable resins include reaction products of one or more alkanolamines and an epoxy-functional material containing at least two epoxy groups, such as those disclosed in U.S. Pat. No. 5,653,823. In some cases, such resins contain beta hydroxy ester, imide, or sulfide functionality, incorporated by using dimethylolpropionic acid, phthalimide, or mercaptoglycerine as an additional reactant in the preparation of the resin. Alternatively, the reaction product is that of the diglycidyl ether of Bisphenol A (commercially available from Shell Chemical Company as EPON 880), dimethylol propionic acid, and diethanolamine in a 0.6 to 5.0:0.05 to 5.5:1 mole ratio. Other suitable resinous binders include water soluble and water dispersible polyacrylic acids as disclosed in U.S. Pat. Nos. 3,912,548 and 5,328,525; phenol formaldehyde resins as described in U.S. Pat. No. 5,662,746; water soluble polyamides such as those disclosed in WO 95/33869; copolymers of maleic or acrylic acid with allyl ether as described in Canadian patent application 2,087,352; and water soluble and dispersible resins including epoxy resins, aminoplasts, phenol-formaldehyde resins, tannins, and polyvinyl phenols as discussed in U.S. Pat. No. 5,449,415.

The resinous binder often may be present in the pretreatment composition in an amount of 0.005 percent to 30 percent by weight, such as 0.5 to 3 percent by weight, based on the total weight of the ingredients in the composition.

The pretreatment composition may be substantially free or, in some cases, completely free of any resinous binder. As used herein, the term “substantially free,” when used with reference to the absence of resinous binder in the pretreatment composition, means that any resinous binder is present in the pretreatment composition in a trace amount of less than 0.005 percent by weight. As used herein, the term “completely free” means that there is no resinous binder in the pretreatment composition at all.

In examples, the solution or dispersion of the pretreatment composition may be spontaneously applied or contacted to the substrate surface. For example, the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. The solution or dispersion, when applied to the metal substrate, may be at a temperature ranging from 20° C. to 50° C., such as 25° C. to 40° C. For example, the pretreatment process may be carried out at ambient or room temperature. The contact time is often from 15 seconds to 5 minutes, such as 30 seconds to 4 minutes, such as 1 minute to 3 minutes. As used herein, “spontaneous” or “spontaneously”, when used with respect to a pretreatment composition, refers to a pretreatment composition that is capable of reacting with and chemically altering the substrate surface and binding to it to form a protective layer in the absence of an externally applied voltage.

Following application of the pretreatment composition to at least a portion of a surface of the substrate, the substrate optionally may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents to remove any residue. The wet substrate surface optionally may be treated with one of the film-forming resins described herein below or the substrate may be dried prior to further treating the substrate surface, such as air dried, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls.

At least a portion of the substrate surface may be cleaned prior to contacting at least a portion of the substrate with one of the pretreatment compositions described herein to remove grease, dirt, and/or other extraneous matter. At least a portion of the surface of the substrate may be cleaned by physical and/or chemical means, such as mechanically abrading the surface and/or cleaning/degreasing the surface with commercially available alkaline or acidic cleaning agents that are well known to those skilled in the art. Examples of alkaline cleaners suitable for use include ChemkleenTM 166HP. 166 M/C, 177, 181ALP. 490MX, 2010LP, and Surface Prep 1 (SP1), Ultrax 32, Ultrax 97, Ultrax 29, and Ultrax 92D, each of which are commercially available from PPG Industries, Inc. (Cleveland, OH), and any of the DFM Series, RECC 1001, and 88X1002 cleaners (commercially available from PRC-DeSoto International, Sylmar, CA), and Turco 4215-NCLT and Ridolene (commercially available from Henkel Technologies, Madison Heights, MI). Examples of acidic cleaners suitable for use include Acid Metal Cleaner (AMC) 23, AMC 239, AMC 240, and AMC 533, AMC66AW and acetic acid. Such cleaners are often preceded and/or followed by a water rinse, such as with tap water, distilled water, or combinations thereof.

Following the cleaning step(s), the substrate optionally may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents to remove any residue. The wet substrate may be treated with one of the pretreatment compositions described above or the substrate may be dried prior to treating the substrate surface, such as air dried, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls.

As discussed above, the present disclosure is directed to a pretreatment composition for treating at least a portion of the surface of a metal substrate. Optionally, a coating composition may be applied to the portion of the surface of the metal substrate treated with the pretreatment composition. The coating composition may comprise, or consist essentially of, or consist of, a film-forming resin. Any suitable technique may be used to deposit such a coating composition onto the substrate, including, for example, brushing, dipping, flow coating, spraying and the like. Optionally, however, as described in more detail below, such depositing of a coating composition may comprise an electrocoating step wherein an electrodepositable coating composition is deposited onto a metal substrate by electrodeposition. In certain other instances, as described in more detail below, such depositing of a coating composition comprises a powder coating step. In still other instances, the coating composition may be a liquid coating composition.

The coating composition may comprise a thermosetting film-forming resin or a thermoplastic film-forming resin. As used herein, the term “film-forming resin” refers to resins that can form a self-supporting continuous film on at least a horizontal surface of a substrate upon removal of any diluents or carriers present in the composition and/or upon curing at ambient or elevated temperature. Conventional film-forming resins that may be used include, without limitation, those typically used in automotive OEM coating compositions, automotive refinish coating compositions, industrial coating compositions, architectural coating compositions, coil coating compositions, and aerospace coating compositions, among others. As used herein, the term “thermosetting” refers to resins that “set” irreversibly upon curing or crosslinking, wherein the polymer chains of the polymeric components are joined together by covalent bonds. This property is usually associated with a cross-linking reaction of the composition constituents often induced, for example, by heat or radiation. Curing or crosslinking reactions also may be carried out under ambient conditions. Once cured or crosslinked, a thermosetting resin will not melt upon the application of heat and is insoluble in solvents. As used herein, the term “thermoplastic” refers to resins that comprise polymeric components that are not joined by covalent bonds and thereby can undergo liquid flow upon heating and are soluble in solvents.

As previously indicated, the coating composition may be an electrodepositable coating composition comprising a water-dispersible, ionic salt group-containing film-forming resin that may be deposited onto the substrate by any electrocoating step wherein the electrodepositable coating composition is deposited onto the metal substrate under the influence of any applied electrical potential, i.e., by electrodeposition. The ionic salt group-containing film-forming polymer may comprise a cationic salt group containing film-forming polymer for use in a cationic electrodepositable coating composition. As used herein, the term “cationic salt group-containing film-forming polymer” refers to polymers that include at least partially neutralized cationic groups, such as sulfonium groups and ammonium groups, that impart a positive charge. The cationic salt group-containing film-forming polymer may comprise active hydrogen functional groups, including, for example, hydroxyl groups, primary or secondary amino groups, and thiol groups. Cationic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, cationic salt group-containing film-forming polymer include, but are not limited to, alkyd polymers, acrylics, polyepoxides, polyamides, polyurethanes, polyurcas, polyethers, and polyesters, among others. The cationic salt group-containing film-forming polymer may be present in the cationic electrodepositable coating composition in an amount of 40% to 90% by weight, such as 50% to 80% by weight, such as 60% to 75% by weight based on the total weight of the resin solids of the electrodepositable coating composition. As used herein, the “resin solids” include the ionic salt group-containing film-forming polymer, curing agent (as discussed below), and any additional water-dispersible non-pigmented component(s) present in the electrodepositable coating composition.

Alternatively, the ionic salt group containing film-forming polymer may comprise an anionic salt group containing film-forming polymer for use in an anionic electrodepositable coating composition. As used herein, the term “anionic salt group containing film-forming polymer” refers to an anionic polymer comprising at least partially neutralized anionic functional groups, such as carboxylic acid and phosphoric acid groups that impart a negative charge. The anionic salt group-containing film-forming polymer may comprise active hydrogen functional groups. Anionic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, anionic salt group-containing film-forming polymers. The anionic salt group-containing film-forming polymer may comprise base-solubilized, carboxylic acid group-containing film-forming polymers such as the reaction product or adduct of a drying oil or semi-drying fatty acid ester with a dicarboxylic acid or anhydride; and the reaction product of a fatty acid ester, unsaturated acid or anhydride and any additional unsaturated modifying materials which are further reacted with polyol. Also suitable are the at least partially neutralized interpolymers of hydroxy-alkyl esters of unsaturated carboxylic acids, unsaturated carboxylic acid and at least one other ethylenically unsaturated monomer. Still another suitable anionic electrodepositable resin comprises an alkyd-aminoplast vehicle, i.e., a vehicle containing an alkyd resin and an amine-aldehyde resin. Another suitable anionic electrodepositable resin composition comprises mixed esters of a resinous polyol. Other acid functional polymers may also be used such as phosphatized polyepoxide or phosphatized acrylic polymers. Exemplary phosphatized polyepoxides are disclosed in U.S. Patent Application Publication No. 2009-0045071 at pars. [0004]-[0015] and U.S. patent application Ser. No. 13/232,093 at pars. [0014]-[0040], the cited portions of which being incorporated herein by reference. The anionic salt group-containing film-forming polymer may be present in the anionic electrodepositable coating composition in an amount of 50% to 90% based on the total weight of resin solids of the electrodepositable coating composition, such as 55% to 80%, such as 60% to 75%.

The electrodepositable coating composition may further comprise a curing agent. The curing agent may comprise functional groups that are reactive with the functional groups of the ionic salt group-containing film-forming polymer, such as active hydrogen groups, to effectuate cure of the coating composition to form a coating. Non-limiting examples of suitable curing agents are at least partially blocked polyisocyanates, aminoplast resins and phenoplast resins, such as phenolformaldehyde condensates including allyl ether derivatives thereof. The curing agent may be present in the cationic electrodepositable coating composition in an amount of 10% to 60% by weight, such as 20% to 50% by weight, such as 25% to 40% by weight based on the total weight of the resin solids of the electrodepositable coating composition.

Alternatively, the curing agent may be present in the anionic electrodepositable coating composition in an amount of 10% to 50% by weight, such as 20% to 45% by weight, such as 25% to 40% by weight based on the total weight of the resin solids of the electrodepositable coating composition.

The electrodepositable coating composition may further comprise other optional ingredients, such as a pigment composition and, if desired, various additives such as fillers, plasticizers, antioxidants, biocides, UV light absorbers and stabilizers, hindered amine light stabilizers, defoamers, fungicides, dispersing aids, flow control agents, surfactants, wetting agents, or combinations thereof.

The electrodepositable coating composition may comprise water and/or one or more organic solvent(s). Water can for example be present in amounts of 40% to 90% by weight, such as 50% to 75% by weight based on total weight of the electrodepositable coating composition. If used, the organic solvents may typically be present in an amount of less than 10% by weight, such as less than 5% by weight based on total weight of the electrodepositable coating composition. The electrodepositable coating composition may in particular be provided in the form of an aqueous dispersion. The total solids content of the electrodepositable coating composition may be from 1% to 50% by weight, such as 5% to 40% by weight, such as 5% to 20% by weight based on the total weight of the electrodepositable coating composition. As used herein, “total solids” refers to the non-volatile content of the electrodepositable coating composition, i.e., materials that will not volatilize when heated to 110° C. for 15 minutes.

The cationic electrodepositable coating composition may be deposited upon an electrically conductive substrate by placing the composition in contact with an electrically conductive cathode and an electrically conductive anode, with the surface to be coated being the cathode. Alternatively, the anionic electrodepositable coating composition may be deposited upon an electrically conductive substrate by placing the composition in contact with an electrically conductive cathode and an electrically conductive anode, with the surface to be coated being the anode. An adherent film of the electrodepositable coating composition is deposited in a substantially continuous manner on the cathode or anode, respectively, when a sufficient voltage is impressed between the electrodes. The applied voltage may be varied and can be, for example, as low as one volt to as high as several thousand volts, such as between 50 and 500 volts. Current density is usually between 1.0 ampere and 15 amperes per square foot (10.8 to 161.5 amperes per square meter) and tends to decrease quickly during the electrodeposition process, indicating formation of a continuous self-insulating film.

Once the cationic or anionic electrodepositable coating composition is electrodeposited over at least a portion of the electroconductive substrate, the coated substrate may be heated to a temperature and for a time sufficient to cure the electrodeposited coating on the substrate. For cationic electrodeposition, the coated substrate may be heated to a temperature ranging from 230° F. to 450° F. (110° C. to 232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.). For anionic electrodeposition, the coated substrate may be heated to a temperature ranging from 200° F. to 450° F. (93° C. to 232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.), such as 200° F. to 210.2° F. (93° C. to 99° C.). The curing time may be dependent upon the curing temperature as well as other variables, for example, the film thickness of the electrodeposited coating, level and type of catalyst present in the composition and the like. For example, the curing time can range from 10 minutes to 60 minutes, such as 20 to 40 minutes. The thickness of the resultant cured electrodeposited coating may range from 10 to 50 microns.

Alternatively, as mentioned above, after the substrate has been contacted with the pretreatment compositions as described above, a powder coating composition may then be deposited onto at least a portion of the pretreated substrate surface. As used herein, “powder coating composition” refers to a coating composition in the form of a co-reactable solid in particulate form which is substantially or completely free of water and/or solvent. Accordingly, the powder coating composition disclosed herein is not synonymous to waterborne and/or solvent-borne coating compositions known in the art. The powder coating composition may comprise (a) a film-forming polymer having a reactive functional group; and (b) a curing agent having a functional group that is reactive with the functional group of the film-forming polymer. Examples of powder coating compositions that may be used in the present disclosure include the polyester-based ENVIROCRON line of powder coating compositions (commercially available from PPG Industries, Inc.) or epoxy-polyester hybrid powder coating compositions. Alternative examples of powder coating compositions that may be used include low temperature cure thermosetting powder coating compositions comprising (a) at least one tertiary aminourca compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,470,752, assigned to PPG Industries, Inc. and incorporated herein by reference); curable powder coating compositions generally comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,432,333, assigned to PPG Industries, Inc. and incorporated herein by reference); and those comprising a solid particulate mixture of a reactive group-containing polymer having a Tg of at least 30° C. (such as those described in U.S. Pat. No. 6,797,387, assigned to PPG Industries, Inc. and incorporated herein by reference). The powder coating compositions are often applied by spraying, electrostatic spraying, or by the use of a fluidized bed. Other standard methods for coating application of the powder coating also can be employed such as brushing, dipping or flowing. After application of the powder coating composition, the coating is often heated to cure the deposited composition. The heating or curing operation is often carried out at a temperature in the range of from 130° C. to 220° C., such as from 170° C. to 190° C., for a period of time ranging from 10 minutes to 30 minutes, such 15 minutes to 25 minutes. The thickness of the resultant film is from 50 microns to 125 microns.

As mentioned above, after the substrate has been contacted with a pretreatment composition as described above, a liquid coating composition may then be applied or deposited onto at least a portion of the substrate surface. As used herein, “liquid coating composition” refers to a coating composition which contains a portion of water and/or solvent that may be substantially or completely removed from the composition upon drying and/or curing. Accordingly, the liquid coating composition disclosed herein is synonymous to waterborne and/or solvent-borne coating compositions known in the art.

The liquid coating composition may comprise, for example, (a) a film-forming polymer having a reactive functional group; and (b) a curing agent having a functional group that is reactive with the functional group of the film-forming polymer. In other examples, the liquid coating may contain a film-forming polymer that may react with oxygen in the air or coalesce into a film with the evaporation of water and/or solvents. These film-forming mechanisms may require or be accelerated by the application of heat or some type of radiation such as Ultraviolet or Infrared. Examples of liquid coating compositions that may be used include the SPECTRACRON® line of solvent-based coating compositions, the AQUACRON® line of water-based coating compositions, and the RAYCRON® line of UV cured coatings (all commercially available from PPG Industries, Inc.). Suitable film-forming polymers that may be used in the liquid coating composition may comprise a (poly) ester, an alkyd, a (poly) urethane, an isocyanurate, a (poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane, or combinations thereof.

The film-forming resin may, in examples, be a primer composition and/or a topcoat composition. The primer and/or topcoat compositions may be, for example, chromate-based primers and/or advanced performance topcoats. The primer coat can be a conventional chromate-based primer coat, such as those available from PPG Industries, Inc. (product code 44GN072), or a chrome-free primer such as those available from PPG (DESOPRIME CA7502, DESOPRIME CA7521, Deft 02GN083, Deft 02GN084). Alternately, the primer coat can be a chromate-free primer coat, such as the coating compositions described in U.S. patent application Ser. No. 10/758,973, titled “CORROSION RESISTANT COATINGS CONTAINING CARBON”, and U.S. patent application Ser. Nos. 10/758,972; 10/346,374, both titled “CORROSION RESISTANT COATINGS”, all of which are incorporated herein by reference, and other chrome-free primers that are known in the art, and which can pass the military requirement of MIL-PRF-85582 Class N or MIL-PRF-23377 Class N, may also be used with the current disclosure.

As mentioned above, the substrate of the present disclosure also may comprise a topcoat. As used herein, the term “topcoat” refers to a mixture of binder(s) which can be an organic or inorganic based polymer or a blend of polymers, typically at least one pigment, can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. A topcoat is typically the coating layer in a single or multi-layer coating system whose outer surface is exposed to the atmosphere or environment, and its inner surface is in contact with another coating layer or polymeric substrate. Examples of suitable topcoats include those conforming to MIL-PRF-85285D, such as those available from PPG (Deft 03W127A and Deft 03GY292). The topcoat may be an advanced performance topcoat, such as those available from PPG (Defthane® ELT.TM. 99GY001 and 99W009). However, other topcoats and advanced performance topcoats can be used as will be understood by those of skill in the art with reference to this disclosure.

The metal substrate also may comprise a self-priming topcoat, or an enhanced self-priming topcoat. The term “self-priming topcoat”, also referred to as a “direct to substrate” or “direct to metal” coating, refers to a mixture of a binder(s), which can be an organic or inorganic based polymer or blend of polymers, typically at least one pigment, can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. The term “enhanced self-priming topcoat”, also referred to as an “enhanced direct to substrate coating” refers to a mixture of functionalized fluorinated binders, such as a fluoroethylene-alkyl vinyl ether in whole or in part with other binder(s), which can be an organic or inorganic based polymer or blend of polymers, typically at least one pigment, can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. Examples of self-priming topcoats include those that conform to TT-P-2756A. Examples of self-priming topcoats include those available from PPG (03W169 and 03GY369), and examples of enhanced self-priming topcoats include Defthane® ELTTM/ESPT and product code number 97GY121, available from PPG. However, other self-priming topcoats and enhanced self-priming topcoats can be used in the coating system as will be understood by those of skill in the art with reference to this disclosure.

The self-priming topcoat and enhanced self-priming topcoat may be applied directly to the pretreated substrate. The self-priming topcoat and enhanced self-priming topcoat can optionally be applied to an organic or inorganic polymeric coating, such as a primer or paint film. The self-priming topcoat layer and enhanced self-priming topcoat is typically the coating layer in a single or multi-layer coating system where the outer surface of the coating is exposed to the atmosphere or environment, and the inner surface of the coating is typically in contact with the substrate or optional polymer coating or primer.

The topcoat, self-priming topcoat, and enhanced self-priming topcoat can be applied to the pretreated substrate, in either a wet or “not fully cured” condition that dries or cures over time, that is, solvent evaporates and/or there is a chemical reaction. The coatings can dry or cure either naturally or by accelerated means for example, an ultraviolet light cured system to form a film or “cured” paint.

In addition, a colorant and, if desired, various additives such as surfactants, wetting agents or catalysts can be included in the coating composition (electrodepositable, powder, or liquid). As used herein, the term “colorant” means any substance that imparts color and/or other opacity and/or other visual effect to the composition. Example colorants include pigments, dyes and tints, such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA), as well as special effect compositions. In general, the colorant can be present in the coating composition in any amount sufficient to impart the desired visual and/or color effect. The colorant may comprise from 1 to 65 weight percent, such as from 3 to 40 weight percent or 5 to 35 weight percent, with weight percent based on the total weight of the coating composition.

The present disclosure also is directed to a method for treating a substrate. In examples, the method of treating may comprise, or may consist essentially of, or may consist of, contacting at least a portion of a surface of the substrate with one of the pretreatment compositions described herein. For example, the pretreatment composition may comprise, consist essentially of, or consist of, a Group IVB metal in an amount of 500 ppm to 5,000 ppm based on total weight of the pretreatment composition; total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition; and an electropositive metal. For example, the pretreatment composition may comprise a Group IVB metal greater than 500 ppm based on total weight of the pretreatment composition; and free fluoride in an amount of 50 ppm to 750 ppm based on total weight of the pretreatment composition; wherein the pretreatment composition has a pH greater than 4.

In examples, the method excludes treating the substrate with more than one pretreatment composition. That is, the method may exclude contacting at least a portion of the substrate with a second or more pretreatment composition.

For example, the method may comprise, or consist essentially of, or consist of, contacting at least a portion of a substrate surface with a pretreatment composition comprising, or consisting essentially of, or consisting of, a Group IVB metal in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition, total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition, and an electropositive metal, without contacting at least a portion of the substrate surface with a second pretreatment composition.

For example, the pretreatment composition may comprise, or consist essentially of, or consist of, contacting at least a portion of a substrate surface with a pretreatment composition comprising, or consisting essentially of, or consisting of, a Group IVB metal in an amount greater than 500 ppm based on total weight of the pretreatment composition, and free fluoride in an amount of 50 ppm to 750 ppm based on total weight of the pretreatment composition, wherein the pretreatment composition has a pH greater than 4, without contacting at least a portion of the substrate surface with a second pretreatment composition.

The method may further comprise, for example, contacting at least a portion of the substrate surface with a cleaner composition and/or a film-forming resin. There optionally may be rinse steps that intervene the contacting with the pretreatment composition and the cleaning composition and/or the film-forming resin.

The present disclosure also is directed to a system for treating a substrate. In examples, the system may comprise, or may consist essentially of, or may consist of, one of the pretreatment compositions described herein. For example, the system may comprise, or may consist essentially of, or may consist of, a cleaner composition and/or a film-forming resin and a pretreatment composition comprising, or consisting essentially of, or consisting of, a Group IVB metal in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition; total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition; and an electropositive metal. For example, the system may comprise, or may consist essentially of, or may consist of, a cleaner composition and/or a film-forming resin and a pretreatment composition comprising, or consisting essentially of, or consisting of, a Group IVB metal greater than 500 ppm based on total weight of the pretreatment composition, and free fluoride in an amount of 50 ppm to 750 ppm based on total weight of the pretreatment composition, wherein the pretreatment composition has a pH greater than 4. In examples, the system may exclude second or more pretreatment compositions.

The present disclosure also is directed to a system for treating a substrate comprising a first pretreatment composition comprising a Group IVB metal and free fluoride; and a second pretreatment composition comprising a Group IVB metal present in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition, total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition, and an electropositive metal, wherein the first pretreatment composition and the second pretreatment composition do not indicate a particular order in which a substrate is contacted with the pretreatment compositions. The amounts of the Group IVB metal and free fluoride in the first pretreatment composition and the amounts of Group IVB, total fluoride, and electropositive metal may be the same as described above.

The present disclosure also is directed to a substrate that has been treated on at least a portion of a surface with one of the pretreatment compositions disclosed herein. As stated above, disclosed also is a substrate comprising a film formed from one of the pretreatment compositions described herein on at least a portion thereof, wherein the film comprises an electropositive metal and optionally a Group IVB metal, wherein the electropositive metal is present in an amount of at least 1 atomic % as measured by XRF.

Suitable substrates that may be used include metal substrates, metal alloy substrates, and/or substrates that have been metallized, such as nickel-plated plastic. The metal or metal alloy can comprise or be steel, aluminum, zinc, nickel, and/or magnesium. For example, the steel substrate could be cold rolled steel, hot rolled steel, electrogalvanized steel, and/or hot dipped galvanized steel. Aluminum alloys of the 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, or 7XXX series as well as clad aluminum alloys also may be used as the substrate. Aluminum alloys may comprise, for example, 0.01% by weight copper to 10% by weight copper. Aluminum alloys which are treated may also include castings, such as 1XX.X, 2XX.X, 3XX.X, 4XX.X, 5XX.X. 6XX.X. 7XX.X, 8XX.X, or 9XX.X (e.g., A356.0). Magnesium alloys of the AZXX (including Eform Plus), AMXX, EVXX, ZEXX, ZCXX, HKXX, HZXX, QEXX, QHXX, WEXX, ZEK100, or Elektron 21 series also may be used as the substrate. The substrate used may also comprise titanium and/or titanium alloys, zinc and/or zinc alloys, and/or nickel and/or nickel alloys. Suitable substrates for use in the present disclosure include those that are often used in the assembly of vehicular bodies (e.g., without limitation, door, body panel, trunk deck lid, roof panel, hood, roof and/or stringers, rivets, landing gear components, and/or skins used on an aircraft), a vehicular frame, vehicular parts, motorcycles, wheels, industrial structures and components such as appliances, including washers, dryers, refrigerators, stoves, dishwashers, and the like, personal electronics, agricultural equipment, lawn and garden equipment, air conditioning units, heat pump units, heat exchangers, lawn furniture, and other articles. As used herein, “vehicle” or variations thereof includes, but is not limited to, civilian, commercial and military aircraft, and/or land vehicles such as cars, motorcycles, and/or trucks. The metal substrate also may be in the form of, for example, a sheet of metal or a fabricated part.

In examples, the substrate may be a multi-metal article. As used herein, the term “multi-metal article” refers to (1) an article that has at least one surface comprised of a first metal and at least one surface comprised of a second metal that is different from the first metal, (2) a first article that has at least one surface comprised of a first metal and a second article that has at least one surface comprised of a second metal that is different from the first metal, or (3) both (1) and (2).

In examples, the substrate may comprise a three-dimensional component formed by an additive manufacturing process such as selective laser melting, e-beam melting, directed energy deposition, binder jetting, metal extrusion, and the like. In examples, the three-dimensional component may be a metal and/or resinous component.

The substrate may comprise a coating or film on at least a portion of the substrate surface. The coating or film may be formed from any of the pretreatment compositions disclosed herein. The substrate may be treated according to any of the methods disclosed herein. The substrate may further comprise a coating formed from a film-forming resin.

Whereas aspects of the disclosure 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 limited as to the scope of the disclosure which is to be given the full breadth of the claims and aspects appended and any and all equivalents thereof.

EXAMPLES

Preparation of alkaline cleaner: In order to remove the surface oil from the metal substrates, an alkaline cleaner solution was prepared as follows. A rectangular stainless-steel tank with a total volume of 37 gallons, equipped with spray nozzles, was filled with 10 gallons of deionized water. To this was added 500 mL of Chemkleen 2010LP (a phosphate-free alkaline cleaner available from PPG Industries, Inc.) and 50 mL of Chemkleen 181ALP (a phosphate-free blended surfactant additive available from PPG Industries, Inc.), and the solution temperature was raised to 120° F.

A 10 mL sample of the alkaline cleaner was titrated with 0.100 N sulfuric acid to measure the free and total alkalinity. The free alkalinity was 5.2 mL as measured using a phenolphthalein end point (pink to colorless color change) and the total alkalinity was 6.4 mL as measured to a bromocresol green end point (blue to yellow color change). This cleaner composition was used in each of the Examples disclosed below.

Preparation of pretreatment: Thirteen different pretreatment compositions (PT 1-13) were prepared for testing. The compositions are listed in Table 1 below. Free fluoride was supplied by adding potassium bifluoride (99.3%), available from Sigma-Aldrich (St. Louis, MO); zirconium was supplied by adding fluorozirconic acid (45 wt. % in water) available from Honeywell International, Inc. (Morristown, NJ); yttrium was supplied by adding yttrium nitrate, available from ProChem, Inc. (Rockford, IL); copper was supplied by adding a 2 wt. % Cu solution, which was prepared by dilution of a copper nitrate solution (18 wt. % Cu in water) available from Shepherd Chemical Company (Cincinnati, OH); and silver was supplied by adding solid silver (I) nitrate from Fisher Scientific/Agros Organics (Fair Lawn, NJ).

All of the compositions, as detailed below, were prepared in deionized water and maintained at 80° F. with an immersion heater (Polyscience Sous Vide Professional, Model #7306AC1B5, available from Polyscience, Niles, Illinois). Baths containing pretreatment were set to low agitation mode during immersion of panels to circulate and heat the composition contained therein.

After the ingredients were added to the pretreatment bath, pH was measured using a PH meter (interface, DualStar pH/ISE Dual Channel Benchtop Meter, available from ThermoFisher Scientific, Waitham, Massachusetts, USA; pH probe, Fisher Scientific Accumet pH probe (Ag/AgCl reference electrode)) by immersing the pH probe in the pretreatment solution. Then, the pH was adjusted as needed with Chemfil buffer (an alkaline buffering solution, commercially available from PPG Industries, Inc.).

Free fluoride was measured using a DualStar pH/ISE Dual Channel Benchtop Meter (ThermoFisher Scientific) equipped with a fluoride selective electrode (Orion ISE Fluoride Electrode, solid state, available from ThermoFisher Scientific) by immersing the ISE in the pretreatment solution and allowing the measurement to equilibrate. The free fluoride was adjusted as needed with Chemfos AFL (a partially neutralized aqueous ammonium bifluoride solution, commercially available from PPG Industries, Inc. and prepared according to supplier instructions).

The amount of copper in each bath was measured using a DR/890 Colorimeter (available from HACH, Loveland, Colorado, USA) using an indicator (CuVer1 Copper Reagent Powder Pillows, available from HACH). Amounts of yttrium, silver, zirconium, and total fluoride were calculated using standard stoichiometric calculations.

Pretreatment Composition Bath 1 (PT-1): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Fluorozirconic acid (80.13 g), potassium bifluoride (7 g) and sodium hydroxide (9.5 g) were then added.

Pretreatment Composition Bath 2 (PT-2): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Fluorozirconic acid (80.13 g), potassium bifluoride (7 g), and sodium hydroxide (9.5 g) were added, and Chemfil buffer was added to adjust to a pH of 4.5.

Pretreatment Composition Bath 3 (PT-3): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Fluorozirconic acid (80.13 g) was added and Chemfil buffer was added to adjust to a pH of 4.5.

Pretreatment Composition Bath 4 (PT-4): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Fluorozirconic acid (80.13 g), potassium bifluoride (7 g), sodium hydroxide (9.5 g), yttrium nitrate (29.99 g) were added, and Chemfil buffer was added to adjust to a pH of 4.5.

Pretreatment Composition Bath 5 (PT-5): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Hexafluorozirconic acid (80 g), potassium bifluoride (7 g), sodium hydroxide (9.5 g), and a 2% solution of copper (II) nitrate (3 g) were added.

Pretreatment Composition Bath 6 (PT-6): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Hexafluorozirconic acid (80 g), potassium bifluoride (7 g), sodium hydroxide (9.5 g), and a 2% solution of copper (II) nitrate (21 g) were added.

Pretreatment Composition Bath 7 (PT-7): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Hexafluorozirconic acid (80 g), potassium bifluoride (7 g), sodium hydroxide (9.5 g), and silver nitrate (0.09 g) were added.

Pretreatment Composition Bath 8 (PT-8): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Hexafluorozirconic acid (80 g), potassium bifluoride (7 g), sodium hydroxide (9.5 g), and silver nitrate (0.63 g) were added.

Pretreatment Composition Bath 9 (PT-9): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Hexafluorozirconic acid (80 g), potassium bifluoride (7 g), sodium hydroxide (9.5 g), a 2% solution of copper (II) nitrate (3 g) and silver nitrate (0.09 g) were added.

Pretreatment Composition Bath 10 (PT-10): To a clean three-gallon plastic bucket was added 11.25 liters of deionized water. Hexafluorozirconic acid (80 g), potassium bifluoride (7 g), sodium hydroxide (9.5 g), a 2% solution of copper (II) nitrate (21 g) and silver nitrate (0.63 g) were added.

Pretreatment Composition Bath 11 (PT-11): To a clean three-gallon plastic bucket was added 11.37 liters of deionized water. Fluorozirconic acid (11.5 g), a 2% solution of copper (II) nitrate (21 g), and Chemfos AFL (7 g) were added.

Pretreatment Composition Bath 12 (PT-12): To a clean one-gallon plastic bucket was added 3.80 liters of deionized water. Fluorozirconic acid (26.72 g), potassium bifluoride (2.30 g), and sodium hydroxide (3.16 g) were added.

Pretreatment Composition Bath 13 (PT-13): To a clean one-gallon plastic bucket was added 3.80 liters of deionized water. Fluorozirconic acid (26.71 g), potassium bifluoride (2.31 g), sodium hydroxide (3.16 g), and a 2% solution of copper (II) nitrate (6.02 g) were added.

The materials in each of Pretreatment Composition Baths 1-13 were circulated using the immersion heater described above, set to 80° F. and low agitation. The copper, pH and free fluoride were measured as described and, when necessary, the pH was adjusted with 19 g Chemfil buffer.

TABLE 1
Pretreatment Compositions
				Total Group IIIB/		Theoretical
	Group IIIB/		Free	electropositive		total
	electropositive		fluoride	metal	Zirconium	fluoride
Code	metal source	pH	(ppm)	(ppm)	(ppm)	(ppm)
PT 1	—	2.3	81.2	—	1396	2044
PT 2	—	4.5	442.3	—	1396	2044
PT 3	—	4.5	191.5	—	1396	1744
PT 4	Y(NO3)3	4.5	198.8	623	1396	2044
PT 5	Cu(NO3)2	2.5	*	5	1394	2042
PT 6	Cu(NO3)2	2.5	*	35	1394	2042
PT 7	AgNO3	2.5	*	5	1394	2042
PT 8	AgNO3	2.5	*	35	1394	2042
PT 9	Cu(NO3)2,	2.5	*	10	1394	2042
	AgNO3
PT 10	Cu(NO3)2,	2.5	*	70	1394	2042
	AgNO3
PT 11	Cu(NO3)2	4.5	189.6	35	200	312
PT 12	—	2.65	64	—	1392	2035
PT 13	Cu(NO3)2	2.67	110	—	1392	2035
* Not measured

For Examples 1-13, AZ21 magnesium alloy (known commercially as “Eform Plus” or abbreviated “EFP”) was supplied by USAMP from POSCO (Pohang, SK). Cold-rolled steel (CRS) panels and Aluminum alloy 6111 (AA6111) panels, both from ACT Test Panels (Hillsdale, MI), were evaluated. All substrates were cut to 4″ by 6″ using a panel cutter prior to application of the alkaline cleaner.

Eight panels of each substrate type were treated using Treatment Method A and eight panels of each substrate type were treated using Treatment Method B, outlined in Tables 2 and 3, respectively.

For panels treated according to Treatment Method A, panels were spray cleaned and degreased for 120 seconds at 10-15 psi in the alkaline cleaner (120° F.) using Vee-jet nozzles and rinsed with deionized water by immersing in a deionized water bath (75° F.) for 30 seconds followed by a deionized water spray (75° C.) for 30 seconds rinse using a Melnor Rear-Trigger 7-Pattern nozzle set to shower mode (available from Home Depot). All panels were immersed in one of PT-1 through PT-11 for 120 to 240 seconds (80° F.), rinsed by a deionized water spray rinse using a Melnor Rear-Trigger 7-Pattern nozzle set to shower mode (75° F.) for 30 seconds, and dried with hot air (140° F.) for 120 seconds using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting.

For panels treated according to Treatment Method B, panels were spray cleaned and degreased for 120 seconds at 10-15 psi in the alkaline cleaner (120° F.) using Vee-jet nozzles and rinsed with deionized water by immersing in a deionized water bath (75° F.) for 30 seconds followed by a deionized water spray rinse using a Melnor Rear-Trigger 7-Pattern nozzle set to shower mode (available from Home Depot). All panels were immersed in PT-1 for 120 seconds (80° F.), rinsed by a deionized water spray rinse using a Melnor Rear-Trigger 7-Pattern nozzle set to shower mode (75° F.) for 30 seconds, then were immersed in PT-7 for 120 seconds (80° F.), rinsed by a deionized water spray rinse using a Melnor Rear-Trigger 7-Pattern nozzle set to shower mode (75° F.) for 30 seconds, and dried with hot air (140° F.) for 120 seconds using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting

TABLE 2
Treatment Method A
Step 1A Alkaline cleaner (120 seconds, 120° F.,
        spray application)
Step 2A Deionized water rinse (30 seconds, 75° F.,
        immersion application)
Step 3A Deionized water rinse (30 seconds, 75° F.,
        spray application)
Step 4A Pretreatment (120-240 seconds, 80° F.,
        immersion application)
Step 5A Deionized water rinse (30 seconds, 75° F.,
        spray application)
Step 6A Hot Air Dry (120 seconds, 140° F.)

TABLE 3
Treatment Method B
Step 1 Alkaline cleaner (120 seconds, 120° F.,
       spray application)
Step 2 Deionized water rinse (30 seconds, 75° F.,
       immersion application)
Step 3 Deionized water rinse (30 seconds, 75° F.,
       spray application)
Step 4 First Pretreatment (PT-1) 120 seconds, 80° F.,
       immersion application)
Step 5 Deionized water rinse (30 seconds, 75° F.,
       spray application)
Step 6 Second Pretreatment (PT-7, 120 seconds, 80° F.,
       immersion application)
Step 7 Deionized water rinse (30 seconds, 75° F.,
       spray application)
Step 8 Hot Air Dry (120 seconds, 140° F.)

In all Examples, following completion of Treatment Method A or B, seven out of eight of the panels of each substrate type were treated with EPIC 200 FRAP (a cationic electrocoat with components commercially available from PPG Industries, Inc.). In all cases, the electrocoat paint was ultrafiltered, removing 25% of the material, which was replenished with fresh deionized water. The rectifier (Xantrax Model XFR600-2, Elkhart, Indiana, or Sorensen XG 300-5 6, Ameteck, Berwyn, Pennsylvania) was DC power supplied. The electrocoat application conditions were a voltage set point of 170V-180V, a ramp time of 30s, and a current density of 1.6 mA/cm2. The electrocoat was maintained at 92° F. The film thickness was coulomb controlled to deposit a target dry film thickness (DFT) of 0.75+0.2 mils for EPIC 200 FRAP. Following deposition of the electrocoat, panels were baked in an oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes.

Electrocoated panels were vertically or X-scribed on one side of the panel down to the metal substrate. For corrosion performance evaluation, panels were placed in ASTM G85 A2 testing for a minimum of 5 weeks (i.e., 35 cycles) or CASS (Copper Accelerated Acetic Acid Salt Spray) testing for a minimum of 1 week or GMW14872 for a minimum of 30 cycles (i.e., 30 days), as shown in Tables 4a and 4b. After the exposure, corroded panels were dried under ambient conditions. The loose coating around the X-scribe was removed by applying a scotch filament tape (3M Industries Adhesives and Tapes Divisions, St. Paul, MN) and pulling it off. Afterwards, the width of exposed metal region along the scribe was recorded for 5-12 locations and averaged to assess the corrosion performance of the panel. In cases when scribe creep was too wide or the coating came off while tape pulling, the scribe width was reported as “Fail” and indicates catastrophic delamination of the electrocoat layer that precluded reliable scribe creep measurements. As used herein, scribe creep refers to the area of paint loss around the scribe either through corrosion or disbondment (e.g., affected paint to affected paint). One skilled in the art understands that there is an inherent variability between conditions of different corrosion tests and that therefore corrosion performance of treated panels may vary from one standardized corrosion test to another (e.g., from ASTM G85 A2 testing to CASS testing).

TABLE 4a
CRS Panels
Analysis Type                Number of Panels
Retained (non-electrocoated; 1
for XRF analysis)
Film Build                   1
GMW14872                     2
G-85                         2
Crosshatch                   1
Flash Rust                   1

TABLE 4b
EFP Panels
Analysis Type                Number of Panels
Retained (non-electrocoated; 1
for XRF analysis)
Film Build                   1
CASS                         2
G-85                         2
Crosshatch                   1
Humidity                     1

As described below, the non-electrocoated panels were analyzed for deposition of zirconium using hand-held X-ray fluorescence (XRF) (measured using X-Met 7500, Oxford Instruments; operating parameters for zirconium: 30 second timed assay, 40 Kv, 9 μA, Ka, T (p)=1.1 μs (reported as Zr counts below)). Other non-electrocoated panels were analyzed for deposition of oxygen, fluorine, zirconium, copper, and silver using a PANalytical-Axios DY1474 (reported as atomic % below). The accelerating voltages used to determine the elemental quantities are shown in Table 5.

TABLE 5
Accelerating Voltages of Elements for PANalytical-Axios DY1474
        Accelerating Voltage
Element (kV)
O       25
F       25
Cu      25
Ag      60
Zr      25, 60

Example 1

EFP, AA6111, and CRS panels were treated according to Treatment Method A (Table 2). One panel each of EFP, AA6111, and CRS were analyzed using hand-held XRF, as described above. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 6.

TABLE 6
Scribe Creep Results for Example 1
		EFP G-85		AA6111 G-85	CRS Cycle B
Pretreatment	Immersion	scribe creep	EFP XRF	scribe creep	scribe creep	CRS XRF
Code	Time (s)	(42 cycles, mm)	Zr (counts)	(42 cycles, mm)	(30 cycles, mm)	Zr (counts)
PT-1	120	1.08	1012	1.44	20.66	77
PT-1	180	1.16	1200	—	19.52	72
PT-1	240	0.80	1222	—	16.89	96
PT-11	120	10.64	640	3.87	2.12	170
PT-11	180	12.14	723	—	2.35	194
PT-11	240	15.50	738	—	2.49	270

These data show that as more zirconium is deposited on a substrate surface, the corrosion performance improves. However, pretreatment of a substrate with each of PT-1 and PT-11 results in deposition of high levels of zirconium on one kind of substrate. That is, while pretreatment of an EFP substrate with PT-1 results in higher counts of zirconium on the substrate surface, pretreatment of a CRS substrate with PT-1 results in lower counts of zirconium on the substrate surface. In contrast, pretreatment of a CRS substrate with PT-11 results in higher counts of zirconium on the substrate surface, but lower counts of zirconium on the surface of an EFP substrate.

Example 2

EFP, AA6111, and CRS panels were treated according to Treatment Method A (Table 2). One panel each of EFP, AA6111, and CRS were analyzed for deposition of zirconium using hand-held XRF, as described above. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 7.

TABLE 7
Scribe Creep Results for Example 2
		EFP G-85		AA6111 G-85	CRS Cycle B
Pretreatment	Immersion	scribe creep	EFP XRF	scribe creep	scribe creep	CRS XRF
Code	Time (s)	(42 cycles, mm)	Zr (counts)	(42 cycles, mm)	(30 cycles, mm)	Zr (counts)
PT-2	120	1.06	601	2.28	4.79	138
PT-2	180	1.17	716	—	3.22	167
PT-2	240	1.41	733	—	3.99	167
PT-3	120	1.71	666	—	2.44	140
PT-3	180	2.04	659	—	2.31	211
PT-3	240	2.80	753	—	3.67	219
PT-4	120	1.55	668	—	4.06	308
PT-4	180	4.37	634	—	3.85	302
PT-4	240	4.83	690	—	4.53	310

These data show that pretreatment of substrates with either PT-2, PT-3, or PT-4 resulted in good corrosion performance on EFP, CRS, and AA6111. XRF indicates that there was an increase in Zr deposition on CRS panels pretreated with PT-2, PT-3, or PT-4 in comparison to the Zr deposition on CRS panels pretreated with PT-1 (Table 6). Pretreatment of EFP panels with either PT-2, PT-3, or PT-4 resulted in Zr deposition on the substrate surface that was comparable to Zr deposition achieved on EFP panels pretreated with PT-11 (Table 6).

Example 3

EFP and CRS panels were treated with PT-1 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 8.

TABLE 8
Scribe Creep Results for Example 3
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	6.17	32.24
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	5.36	—
	Creep (mm)
	GMW14872 Scribe	—	17.5
	Creep (mm)
	% O (XRF)	11.9	0.72
	% F (XRF)	16.1	0
	% Zr (XRF)	5.7	0
	% Cu (XRF)	0.19	0.12
	% Ag (XRF)	0	0

These data show the base formulation (PT-1) without an electropositive metal gave good corrosion performance on EFP panels and poor corrosion performance on CRS panels. There was very little copper deposition on CRS panels, but significant conversion of the EFP substrate surface, evidenced by the XRF data in Table 8 confirming presence of oxygen, fluoride, zirconium, and copper on the EFP substrate surface.

Example 4

EFP and CRS panels were treated with PT-5 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 9.

TABLE 9
Scribe Creep Results for Example 4
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	8.26	29.73
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	6.34	—
	Creep (mm)
	GMW14872 Scribe	—	13.7
	Creep (mm)
	% O (XRF)	13.7	0.86
	% F (XRF)	13	0
	% Zr (XRF)	5.3	0.007
	% Cu (XRF)	0.36	1.2
	% Ag (XRF)	0	0

These data show a slight increase in copper deposition on both substrates, and an improvement to corrosion performance on CRS compared to PT-1.

Example 5

EFP and CRS panels were treated with PT-6 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 10.

TABLE 10
Scribe Creep Results for Example 5
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	7.47	19.01
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	7.04	—
	Creep (mm)
	GMW14872 Scribe	—	5.8
	Creep (mm)
	% O (XRF)	13.3	2.3
	% F (XRF)	12.5	0
	% Zr (XRF)	7.3	0.065
	% Cu (XRF	1.6	8.7
	% Ag (XRF)	0	0

These data show increased deposition of Cu and Zr on CRS and EFP substrates and significant corrosion improvement compared to panels pretreated with PT-1 and similar corrosion performance on EFP compared to panels pretreated with PT-1.

Example 6

EFP and CRS panels were treated with PT-7 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 11.

TABLE 11
Scribe Creep Results for Example 6
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	8.61	36.29
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	6.35	—
	Creep (mm)
	GMW14872 Scribe	—	15.2
	Creep (mm)
	% O (XRF)	11.9	0.83
	% F (XRF)	9.2	0
	% Zr (XRF)	4.9	0.007
	% Cu (XRF)	0.19	0.1
	% Ag (XRF)	0	0

These data show less deposition of Cu and Zr on both EFP and CRS substrates and slightly worse corrosion performance on EFP and CRS compared to panels pretreated with PT-1. These data demonstrate that the presence of silver, even at low concentrations, interferes with deposition of copper and zirconium and reduces corrosion protection.

Example 7

EFP and CRS panels were treated with PT-8 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 12.

TABLE 12
Scribe Creep Results for Example 7
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	11.48	30.33
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	8.21	—
	Creep (mm)
	GMW14872 Scribe	—	11.1
	Creep (mm)
	% O (XRF)	10.5	0.95
	% F (XRF)	7.7	0
	% Zr (XRF)	5.7	0.013
	% Cu (XRF)	0.13	0.094
	% Ag (XRF)	0.011	0.011

These data show a slight deposition of Ag and Cu on both CRS and EFP substrates. PT-8 resulted in poor corrosion performance on both EFP and CRS substrates. The presence of Cu is much lower on both alloys than what was seen after treatment with PT-5 or PT-6, which may be attributed to Cu present from the alloy or low purity of the Ag (NO₃)₂ used in formulation. This Example shows that the presence of silver in the pretreatment composition fails to provide the improved performance on CRS and comparable performance on EFP compared to a control that the presence of copper achieves.

Example 8

EFP and CRS panels were treated with PT-9 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 13.

TABLE 13
Scribe Creep Results for Example 8
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	9.06	Catastrophic
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	6.74	—
	Creep (mm)
	GMW14872 Scribe	—	11.4
	Creep (mm)
	% O (XRF)	11.1	0.7
	% F (XRF)	15.1	0
	% Zr (XRF)	5.3	0.006
	% Cu (XRF)	0.28	1.1
	% Ag (XRF)	0.004	0.006

These data show very small amounts of Ag on both alloys, and small but significant quantities of Cu. There is significant decay of corrosion resistance on CRS, and slightly worse performance on EFP relative to PT-1. This Example demonstrates that adding silver to a pretreatment composition comprising copper results in substantially worse corrosion performance on CRS and reduced copper and zirconium deposition.

Example 9

EFP and CRS panels were treated with PT-11 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 14.

TABLE 14
Scribe Creep Results for Example 9
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	26.13	12.89
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	16.31	—
	Creep (mm)
	GMW14872 Scribe	—	3.2
	Creep (mm)
	% O (XRF)	10.8	2
	% F (XRF)	2.4	0
	% Zr (XRF)	0.041	1
	% Cu (XRF)	0.15	1.9
	% Ag (XRF)	0	0

These data show that PT-11 does not sufficiently protect EFP, but greatly improves the corrosion resistance of CRS. Much lower counts of F, Zr, and Cu are observed on EFP relative to PT-1, which explains this behavior. In contrast, larger Zr, O, and Cu deposits are seen on CRS here relative to PT-1, which provide the protective conversion coating on that substrate.

Example 10

EFP and CRS panels were treated according to Treatment Method B (Table 3). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 15.

TABLE 15
Scribe Creep Results for Example 10
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	8.57	12.42
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	5.87	—
	Creep (mm)
	GMW14872 Scribe	—	3.1
	Creep (mm)
	% O (XRF)	13.4	2.4
	% F (XRF)	16.9	0
	% Zr (XRF)	5.5	1.3
	% Cu (XRF)	0.17	2.5
	% Ag (XRF)	0	0

These data demonstrate that a two-step pretreatment process, with a first pretreatment demonstrated in Example 3 above to improve corrosion performance on EFP and a second pretreatment demonstrated in Example 9 above to improve corrosion performance on CRS, thereby indicating that the system disclosed herein provides corrosion protection for a multi-metal article. As shown in Table 15, O, Zr, and Cu deposition increased on CRS compared to data shown in Table 8 (Example 3), indicating deposition of a thin-film protective coating on CRS. Table 15 also indicates greater O, F, Zr, and Cu deposition increased on EFP compared to data shown in Table 14 (Example 9), indicating deposition of a thin-film protective coating on EFP.

Example 11

EFP and CRS panels were treated with PT-10 according to Treatment Method A (Table 2). One panel each of EFP and CRS were analyzed for atomic weight % using the PANalytical-Axios DY1474. The remaining panels were then electrocoated with EPIC 200 FRAP according to the parameters described above, then scribed and subjected to cyclic corrosion testing as specified in Table 16.

TABLE 16
Scribe Creep Results for Example 11
	Corrosion Test	EFP	CRS
	ASTM G-85 A2	Catastrophic	18.97
	Scribe Creep
	(5 weeks, mm)
	CASS Scribe	Catastrophic	—
	Creep (mm)
	GMW14872 Scribe	—	6.0
	Creep (mm)
	% O (XRF)	14.4	1.1
	% F (XRF)	9.9	0
	% Zr (XRF)	12.6	0.087
	% Cu (XRF)	0.94	5.9
	% Ag (XRF)	0.014	0.018

These data show less F, increased Zr, Cu, and Ag have deposited on EFP compared to EFP treated with PT-1 (Example 3). The data also show more O, Zr, Cu, and Ag deposited on CRS compared to CRS treated with PT-1 (Example 3). In this example, we observe good corrosion performance on CRS relative to Example 3, and poor corrosion on EFP relative to Example 3. We attribute this behavior to less F deposition on the EFP, which was likely caused by too high a concentration of electropositive metals. The presence of electropositive metals at this concentration did not disrupt formation of a protective coating layer on CRS.

Example 12

Free fluoride of PT-12 and PT-13 were measured as described above using a DualStar pH/ISE Dual Channel Benchtop Meter (ThermoFisher Scientific) equipped with a fluoride selective electrode (Orion ISE Fluoride Electrode, solid state, available from ThermoFisher Scientific). Results are shown in Table 17.

TABLE 17
Free Fluoride Levels of PT-12 and PT-13
	Code	Additive	pH	Free fluoride (ppm)
	PT-1	—	2.3	81.2
	PT-5	Cu(NO3)2	2.5	X
	PT-12	—	2.65	64
	PT-13	Cu(NO3)2	2.67	110

These data demonstrate the free fluoride levels for PT-12 and PT-13, which are compositions comparable to those of PT-1 and PT-5, respectively.

Claims

1. A pretreatment composition comprising:

a Group IVB metal present in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition;

total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition; and

an electropositive metal comprising copper.

2. The pretreatment composition of claim 1, wherein the pretreatment composition is substantially free of a second electropositive metal.

3. The pretreatment composition of claim 1, wherein the pretreatment composition is substantially free of a third metal.

4-5. (canceled)

6. The pretreatment composition of claim 1, wherein copper is present in an amount of 2 ppm to 200 ppm based on total weight of the pretreatment composition.

7. The pretreatment composition of claim 1, wherein the composition comprises a pH of 1 to 5.

8. A pretreatment composition comprising:

a Group IVB metal in an amount of greater than 500 ppm based on total weight of the pretreatment composition; and

free fluoride in an amount of 50 ppm to 750 ppm based on total weight of the pretreatment composition,

wherein the pretreatment composition has a pH greater than 4.

9. The pretreatment composition of claim 8, further comprising a Group IIIB metal.

10. The pretreatment composition of claim 9, wherein the Group IIIB metal is present in an amount of at least 10 ppm based on total weight of the pretreatment composition.

11. The pretreatment composition of claim 8, wherein the Group IIIB metal comprises yttrium.

12-19. (canceled)

20. A method of treating a substrate, comprising contacting at least a portion of a surface of the substrate with the pretreatment composition of claim 1.

21. The method of claim 20, wherein the method excludes contacting the substrate surface with a second pretreatment composition.

22. (canceled)

23. A system for treating a substrate comprising:

a pretreatment composition of claim 1; and

a cleaner composition and/or a film-forming resin.

24. The system of claim 23, wherein the system excludes a second pretreatment composition.

25. A system for treating a substrate comprising:

a first pretreatment composition comprising a Group IVB metal and free fluoride; and

a second pretreatment composition comprising a Group IVB metal present in an amount of 200 ppm to 5,000 ppm based on total weight of the pretreatment composition, total fluoride in an amount of 1,000 ppm to 25,000 ppm based on total weight of the pretreatment composition, and an electropositive metal.

26. The system of claim 25, wherein the second pretreatment composition comprises the electropositive metal in an amount of 2 ppm to 200 ppm, based on total weight of the second pretreatment composition.

27. The system of claim 25, wherein the second pretreatment composition comprises a pH of 1 to 5.

28. (canceled)

29. A substrate comprising a film formed on at least a portion thereof, wherein the film is formed from the pretreatment composition of claim 1.

30. A substrate comprising a film formed on at least a portion thereof, wherein the film is formed from the pretreatment composition of claim 8.

31-33. (canceled)

34. The substrate of claim 30, wherein the substrate comprises aluminum, steel, and/or magnesium.

35-40. (canceled)

41. A system for treating a substrate comprising:

a pretreatment composition of claim 8; and

a cleaner composition and/or a film-forming resin.

42. A method for treating a substrate, comprising contacting at least a portion of a surface of the substrate with the pretreatment composition of claim 8.