ES2972322T3 - Nickel-Free Zinc Phosphate Pretreatment System - Google Patents

Abstract

A substrate pretreatment system is disclosed, comprising (a) an activator rinse for treating at least a portion of a substrate comprising a dispersion of metal phosphate particles having a particle size D90 of no more than 10 μm, in where the metal phosphate comprises divalent or trivalent. metals or combinations thereof; and (b) a pretreatment composition for treating at least a portion of the substrate treated with the activator rinse, comprising zinc ions and phosphate ions, wherein the pretreatment composition is substantially free of nickel. Methods for treating a substrate with the substrate pretreatment system are also described. Substrates treated with the substrate pretreatment system are also described. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Nickel-Free Zinc Phosphate Pretreatment System

field of invention

A system for pretreating a substrate with a nickel-free zinc phosphate pretreatment composition is described.

Background

Phosphate conversion coatings are well known for the treatment of metal surfaces, particularly ferrous metals, zinc and aluminum and their alloys. When applied, these phosphate coatings form a phosphate layer, primarily of zinc iron phosphate crystals, which provides corrosion resistance and/or improves the adhesion of subsequently applied coatings.

Prior to application of the phosphate coating, the metal substrate is typically “conditioned” or “activated” by subjecting the surface of the metal substrate to a dilute aqueous dispersion, sometimes called an activator rinse or activator, by introducing or immersing the substrate. of metal in a tank containing the activator rinse. “Activation” of the metal substrate surface is often achieved due to the adsorption of colloidal titanium phosphate particles, which are present in the activator rinse, to the metal surface. These colloidal titanium phosphate particles, however, have a tendency to agglomerate in the activator rinse bath due to the dissolved cations that are typically present in the conditioning bath of the activator rinse.

Phosphate conversion coating is typically applied to a substrate by immersing the substrate in a heated bath comprising metal phosphate particles.

Conventional techniques for coating such substrates include techniques that involve pretreating the metal substrate with nickel-containing compositions. The use of such nickel-containing compositions, however, imparts environmental concerns.

Document no. WO 01/12341 A1 relates to a metal surface on which a phosphate conversion coating is to be formed and which has been surface conditioned by contact with a liquid surface conditioning composition containing dispersed fine particles of solid phosphate. at least one type of divalent or trivalent metal cations and an adhesion promoting agent. After such conditioning, a conversion coating may be formed on the surface by contact with a nickel-free liquid phosphating composition containing at least zinc cations, phosphate ions and a conversion accelerator.

Document no. WO 00/05066 A1 refers to a conditioning treatment for metal surfaces before phosphating them as it is a suspension in water and contains solid microparticles of at least one phosphate of a divalent or trivalent metal and a specific accelerator.

Document no. US 2007/0240604 A1 refers to a surface conditioning composition that includes bivalent or trivalent metal phosphate particles and an amine compound with a molecular weight of 1000 or less, wherein the metal phosphate particles have a size of D50 particles of 3 pm or less and where the pH of the composition is 3 to 12.

Document no. EP 1930475 A1 refers to a surface conditioning composition comprising a particle of a phosphate of a divalent or trivalent metal, at least one specific metal alkoxide and a stabilizing agent, wherein the phosphate particles have a particle size D50 of 3 pm or less and where the pH of the composition is 3 to 12.

Document no. EP 1930474 A1 refers to a surface conditioning composition comprising a particle of a phosphate of a divalent or trivalent metal, a phenolic compound and a stabilizing agent, wherein the phosphate particles have a particle size D50 of 3 pm or less and where the pH of the composition is from 3 to 12.

Document no. WO 96/16204 A1 relates to zinc phosphate coating compositions containing zinc ions, phosphate ions and an oxime at specific concentrations.

Summary

A metal substrate pretreatment system is described, comprising (a) an activator rinse for treating at least a portion of a substrate comprising a dispersion of metal phosphate particles having a particle size D90 of 50 to 500 nm. , wherein the metal phosphate comprises divalent or trivalent metals or combinations thereof; and (b) a pretreatment composition for treating at least a portion of the substrate treated with the activator rinse, comprising zinc ions and phosphate ions, wherein in the pretreatment composition nickel is only present, if present, in an amount trace of 5 ppm or less, based on a total weight of the composition, and wherein the pretreatment composition further comprises an accelerator, wherein the accelerator includes an oxime, a nitrite, a peroxide or a combination thereof; wherein the particle size D90 determined according to the method described below refers to a volume-weighted particle distribution in which 90% of the particles have a diameter smaller than the D90 value.

Also described is a method of treating a metal substrate with the metal substrate pretreatment system comprising: (a) contacting at least a portion of a surface of the substrate with an activating rinse of the metal substrate pretreatment system previously described; and (b) contacting at least a portion of the surface that has been in contact with the activating rinse with a pretreatment composition comprising zinc ions and phosphate ions, wherein in the pretreatment composition nickel is only present, if is present, in a trace amount of 5 ppm or less, based on the total weight of the composition, and wherein the pretreatment composition further comprises an accelerator, wherein the accelerator includes an oxime, a nitrite, a peroxide or one of their combinations.

Also described is a metal substrate treated with the metal substrate pretreatment system described above.

Detailed description

According to the present invention, the metal substrate pretreatment system comprises, or in some cases consists of, or in some cases consists essentially of: an activator rinse for treating at least a portion of a substrate comprising a dispersion of particles of metal phosphate having a D90 particle size of 50 to 500 nm, wherein the metal phosphate comprises divalent or trivalent metals or combinations thereof; and (b) a pretreatment composition for treating at least a portion of the substrate treated with the activator rinse, comprising zinc ions and phosphate ions, wherein in the pretreatment composition nickel is only present, if present, in an amount trace of 5 ppm or less, based on a total weight of the composition, and wherein the pretreatment composition further comprises an accelerator, wherein the accelerator includes an oxime, a nitrite, a peroxide or a combination thereof; wherein the particle size D90 determined according to the method described below refers to a volume-weighted particle distribution in which 90% of the particles have a diameter smaller than the D90 value.

As used herein, the phrase “activator rinse” refers to a continuous aqueous medium having metal phosphate particles dispersed and/or suspended therein that is applied onto at least a portion of a substrate and/or wherein at least a portion of a substrate is immersed to “activate” or “condition” the substrate in order to promote the formation of a metal phosphate coating on at least a portion of the substrate that was treated with the activator rinse . As used herein, “activate” or “condition” the surface of the substrate means generating nucleation sites on the surface of the substrate. While not wishing to be bound by any theory, it is believed that such nucleation sites promote the formation of metal phosphate crystals on the substrate surface when the substrate surface is subsequently treated with a metal phosphate pretreatment composition. For example, activation of the substrate surface is believed to generate nucleation sites that promote the formation of zinc and zinc/iron phosphate crystals on the substrate surface when the substrate surface is pretreated with a pretreatment composition. of zinc phosphate.

A suitable metal substrate that can be treated with the activator rinse additionally or alternatively includes a metal alloy substrate. For example, the metal and/or metal alloy may comprise or be aluminum, steel or zinc. In accordance with the present invention, a steel substrate may include cold rolled steel, electrogalvanized steel, and hot dipped galvanized steel. In accordance with the present invention, the coated substrate may comprise a portion of a vehicle such as a vehicle body (for example, without limitation, the door, the body panel, the trunk lid, the roof panel, the hood and/or roof) and/or a vehicle frame.

As used herein, the term “vehicle” or variations thereof includes, but is not limited to, civil, commercial and military land vehicles, such as cars and trucks.

As used herein, the term "dispersion" refers to a transparent, translucent or opaque two-phase system in which metal phosphate particles are in the dispersed phase and an aqueous medium, including water, is in the continuous phase. An “aqueous medium” is a liquid medium that is 50 weight percent or more water, with weight percent based on the non-solid content of the activator rinse. The aqueous medium may comprise 50 weight percent or less of other organic cosolvents, such as 10 weight percent or less. According to the present invention, the organic cosolvents are at least partially miscible with water. In the aqueous medium, water-miscible organic solvents may be present, for example, alcohols with up to about 8 carbon atoms such as methanol, isopropanol and the like; or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol or propylene glycol, and the like.

As used herein, the term “pulverized” refers to particles that have variable aspect ratios, where the term “aspect ratio” refers to the relationship between the length and width of a particle (i.e. the aspect ratio does not define a sphere).

According to the present invention, the metal phosphate particles of the dispersion of metal phosphate particles of divalent or trivalent metals or their combinations may have a particle size D90 that is not greater than 500 nm and at least 50 nm and in some cases it may be at least 0.06 gm, such as at least 0.1 gm, such as at least 0.2 gm.

As used herein, the term “D90” particle size refers to a volume-weighted particle distribution in which 90% of the particles in the particle distribution have a diameter less than the “D90” value. . As used herein, the term “D10” particle size refers to a volume-weighted particle distribution in which 10% of the particles in the particle distribution have a diameter less than the “D10” value. . As used herein, the term “D50” particle size refers to a volume-weighted particle distribution in which 50% of the particles in the particle distribution have a diameter less than the “D50” value. .

In accordance with the present invention, particle size can be measured by using an instrument such as a Mastersizer 2000, available from Malvern Instruments, Ltd., Malvern, Worcestershire, United Kingdom, or an equivalent instrument. The Mastersizer 2000 directs a laser beam (0.633 mm diameter, 633 nm wavelength) through a scattering of particles (in distilled, deionized, or filtered water to 2-3% obscuration) and measures the scattering of the scattering light (measuring parameters 25 °C, 2200 RPM, pre-measurement delay 30 seconds, background measurement 10 seconds, sample measurement 10 seconds). The amount of light scattered by scattering is inversely proportional to particle size. An array of detectors measure the scattered light and the data is then analyzed by computer software (Malvern Mastersizer 2000 software, version 5.60) to generate a particle size distribution, from which particle size can be routinely determined. .

In accordance with the present invention, the particle dispersion sample may optionally be sonicated prior to particle size analysis. In accordance with the present invention, the sonication process comprises: (1) mixing the particle dispersion by using a vortex mixer (Fisher Scientific Vortex Genie 2, or equivalent); (2) add 15 ml of ultrafiltered deionized distilled water to a 20 ml screw cap scintillation vial; (3) add 4 drops of the dispersion to the vial; (4) mix the contents of the vial by using the vortex mixer; (5) cap the vial and place it in an ultrasonic water bath (Fisher Scientific Model FS30, or equivalent) for 5 minutes; (6) shake the vial again in a vortex; and (7) add the sample dropwise to the Mastersizer to achieve a darkening between 2-3 for the particle size distribution analysis described above.

According to the present invention, the metal phosphate particles can be substantially pulverized, such that more than 90% of the metal phosphate particles in the activator rinse composition are pulverized, such as more than 91%, such as more 92%, such as more than 93%, such as more than 94%, such as more than 95%, such as more than 96%, such as more than 97%, such as more than 98%, such as more than 99%. According to the present invention, the metal phosphate particles can be completely pulverized, so that 100% of the particles are pulverized.

According to the present invention, the metal phosphate (as a total metal compound) may be present in the activator rinse in an amount of at least 50 ppm, based on the total weight of the activator rinse, such as at least 150 ppm, and in some cases may be present in the activator rinse in an amount of no more than 5000 ppm, based on the total weight of the activator rinse, such as no more than 1500 ppm. According to the present invention, the metal phosphate (as a total metal compound) may be present in the activator rinse in an amount of 50 ppm to 5000 ppm of total metal phosphate based on the total weight of the activator rinse, such as from 150 ppm to 1500 ppm.

According to the present invention, the divalent or trivalent metal of the metal phosphate may comprise zinc, iron, calcium, manganese, aluminum, nickel or combinations thereof. If combinations of different metal phosphates are used, they may comprise the same or different metals, and may be selected from the particular zinc, iron, calcium, manganese and aluminum phosphates mentioned below.

Suitable zinc phosphates useful in the activator rinse bath include, without limitation, Zn3(P04)2, Zn2Fe(P04)2, Zn2Ca(P04)2, Zn2Mn(P04)2 or combinations thereof.

Suitable iron phosphates useful in the activator rinse bath include, without limitation, FeP04, Fe3(P04)2 or combinations thereof.

Suitable calcium phosphates useful in the activator rinse bath include, without limitation, CaHP04, Ca3(P04)2 or combinations thereof.

Suitable manganese phosphates useful in the activator rinse bath include, without limitation, Mn3(P04)2, MnPO* or combinations thereof.

Suitable aluminum phosphates useful in the activator rinse bath include, without limitation, AlP04.

In accordance with the present invention, the activator rinse may further comprise a dispersant. The dispersant can be ionic or non-ionic. Suitable ionic dispersants useful in the activating rinse may comprise an aromatic organic acid, a phenolic compound, a phenolic resin, or combinations thereof. Suitable nonionic dispersants useful in the activating rinse may include nonionic polymers, in particular those compounds of monomers (or residues thereof) including propylene oxide, ethylene oxide, styrene, a monoacid such as (meth)acrylic acid , a diacid such as maleic acid or itaconic acid, an acid anhydride such as acrylic anhydride or maleic anhydride, or combinations thereof. Examples of suitable commercially available nonionic dispersants include DISPERBYK®-190 available from BYK-Chemie GmbH and ZetaSperse® 3100 available from Air Products Chemicals Inc.

In accordance with the present invention, the activator rinse may be substantially free or completely free of ionic dispersants. As used herein, an activator rinse is substantially free of ionic dispersants if the ionic dispersants are present in an amount of less than 1% by weight, based on the total weight of the activator rinse. As used herein, an activator rinse is completely free of ionic dispersants if ionic dispersants are not present in the activator rinse, i.e., 0 wt % based on the total weight of the activator rinse.

In accordance with the present invention, the activator rinse may optionally include a metal sulfate salt. The metal of the metal sulfate may be the same or different to the metal of the metal phosphate particles. According to the present invention, the metal of the metal sulfate salt may comprise a divalent metal, a trivalent metal or combinations thereof, such as, for example, nickel, copper, zinc, iron, magnesium, cobalt, aluminum or their combinations.

In accordance with the present invention, when present, if present, the sulfate ion of the metal sulfate salt may be present in the activator rinse in an amount of at least 5 ppm based on the total weight of the activator rinse, such as such as at least 10 ppm, such as at least 20 ppm, such as at least 50 ppm, and in some cases, no more than the solubility limit of the metal sulfate salt in the activator rinse, such as no more than 5000 ppm, such as not more than 1000 ppm, such as not more than 500 ppm, such as not more than 250 ppm. According to the present invention, the sulfate ion of the metal sulfate salt may be present in an amount of 5 ppm to 5000 ppm based on a total amount of sulfate in the metal sulfate salt, such as 10 ppm to 1000 ppm, such as 20 ppm to 500 ppm, such as 50 ppm to 250 ppm. In accordance with the present invention, the activator rinse may be substantially free, or in some cases, completely free, of sulfate ions. As used herein with respect to the sulfate ion of a metal sulfate salt, the term “substantially free” means that the sulfate ion is present in the activator rinse in an amount of less than 5 ppm based on the total weight. of the activator rinse. As used herein with respect to the sulfate ion of a metal sulfate salt, the term “completely free” means that the activator rinse does not comprise a sulfate ion (i.e., there is 0 ppm sulfate ion (based on the total weight of activator rinse) present in the activator rinse).

According to the present invention, the activator rinse may be in the form of a concentrate, wherein the concentrate has a viscosity sufficient to prevent the metal phosphate particles and the metal sulfate salt (if present) from settling. . In accordance with the present invention, during use, the concentrated activator rinse may be diluted with water and/or an organic solvent.

In accordance with the present invention, the activator rinse may be a 1K composition ("One component" or "One part") or a multi-component composition, such as, for example, 2K compositions ("Two component" or "Two part"). parties"). As defined herein, a "1K" composition is a composition in which all ingredients can be premixed and stored. In contrast, a multi-component composition is one in which at least two of the ingredients are stored separately and mixed together to form the treatment bath.

According to the present invention, the activator rinse may be a 1K composition, wherein the 1K composition is formed from: a dispersion of metal phosphate particles of divalent metals, trivalent metals or combinations thereof, the phosphate particles of metal have a D90 particle size of 50 to 500 nm; a dispersant; and a metal sulfate salt (if present). Optionally, the 1K activator rinse may be a concentrate that is diluted to form the bath containing the activator rinse.

According to the present invention, the activator rinse may be a 2K composition wherein a dispersion of metal phosphate particles of divalent metals, trivalent metals or combinations thereof, the metal phosphate particles having a particle size D90 of 50 to 500 nm, and a dispersant form a part of a first component. A metal sulfate salt may form part of a second component. Additional components comprising any of the optional ingredients described below may also be added to the bath containing the activator rinse. Any of the components of the activator rinse can be a concentrate that is diluted to form the bath containing the activator rinse.

In accordance with the present invention, the activator rinse may include a wetting agent. In accordance with the present invention, wetting agents may be present in amounts of up to 2 weight percent, such as up to 0.5 weight percent, based on the total weight of the activator rinse. In some cases, wetting agents may be present in amounts of 0.1 weight percent to 2 weight percent, based on the total weight of the activator rinse, such as 0.3 weight percent to 0.5 percent by weight. As used herein, a "wetting agent" reduces the surface tension at the interface between the surface of the dispersed phase particles and the aqueous medium to allow the aqueous medium to more uniformly contact or "wet" the surface of the particles of the dispersed phase.

In accordance with the present invention, the activator rinse may have a pH of 6 to 12, such as 6.5 to 9, such as 7.5 to 8.5, such as 7 to 8. A alkaline component in the activator rinse in an amount sufficient to adjust the pH of the activator rinse. Suitable alkaline components may include, for example, sodium hydroxide, sodium carbonate, sodium tripolyphosphate, potassium orthophosphate or combinations thereof.

In accordance with the present invention, the activator rinse may also include a biocide. Suitable biocides include, for example, methylchloroisothiazolinone, methylisothiazolinone or combinations thereof. When used, the biocide may be present in an amount of at least 10 ppm based on the active material in the activator rinse, such as at least 20 ppm, such as at least 80 ppm, such as at least 100 ppm, and in some cases, no more than 140 ppm, such as no more than 120 ppm, such as no more than 40 ppm, such as no more than 30 ppm. According to the present invention, the biocide may be present in an amount of 10 ppm to 140 ppm based on the active material, such as 10 ppm to 40 ppm, such as 20 ppm to 30 ppm, such as 80 ppm. to 140 ppm, such as 100 ppm to 120 ppm. The skilled person will recognize that biocides may be included in the activator rinse in amounts based on the manufacturer's instructions.

In accordance with the present invention, the activator rinse may further comprise silica. In accordance with the present invention, the silica may be a precipitated silica, such as a synthetic amorphous precipitated silica. In accordance with the present invention, the silica may be friable under shear. As used herein, “shear friable” means that the particle size can be reduced with shear. In accordance with the present invention, the silica may comprise, for example, Hi-Sil™ EZ 160G silica (commercially available from PPG Industries, Inc.). In accordance with the present invention, if present, the silica may be present in an amount of at least 50 ppm, based on the total weight of the activator rinse, such as at least 100 ppm, such as at least 150 ppm, and in some cases, no more than 5000 ppm, based on the total weight of the activator rinse, such as no more than 1000 ppm, such as no more than 500 ppm. In accordance with the present invention, silica may be present in the activator rinse in an amount of from 50 ppm to 5000 ppm based on the total weight of the activator rinse, such as from 100 ppm to 1000 ppm, such as from 150 ppm to 500 ppm.

The activator rinse may optionally further comprise components in addition to the dispersant (i.e., components other than the dispersant), such as nonionic surfactants and auxiliaries conventionally used in the art. Such additional optional components include surfactants that function as antifoams. Amphoteric and/or nonionic surfactants can be used. The antifoam surfactants may be present, in any case, in amounts of at least 0.1 weight percent, based on the total weight of the activator rinse bath, such as at least 0.5 weight percent, and in some In some cases, they may be present in amounts of no more than 1 weight percent, such as no more than 0.7 weight percent, based on the total weight of the activator rinse bath. In some cases, the antifoam surfactants may be present, if at all, in amounts of 0.1 weight percent to 1 weight percent, such as 0.5 weight percent to 0.7 weight percent. , based on the total weight of the activator rinse bath.

In accordance with the present invention, the activator rinse may further comprise a rheology modifier in addition to the dispersant (i.e., different from the dispersant). The rheology modifier may comprise, for example, polyurethanes, acrylic polymers, networks, styrene/butadiene, polyvinyl alcohols, clays such as attapulgite, bentonite and other montmorillonite, cellulose-based materials such as carboxymethylcellulose, methylcellulose, (hydroxypropyl)methylcellulose or gelatin, gums such as guar and xanthan, or their combinations.

In accordance with the present invention, the activator rinse may be substantially or, in some cases, completely free of titanium phosphate particles. As used herein, the term “substantially free,” when used in reference to the absence of titanium phosphate particles in the activator rinse, means that any titanium phosphate particles present in the activator rinse are not added. intentionally and is present in a trace amount less than 5 ppm, based on the total weight of the activator rinse. As used herein, the term “completely free,” when used in reference to the absence of titanium phosphate particles, means that there are no titanium phosphate particles.

The activator rinse of the present invention can be prepared fresh with the above-mentioned ingredients in the specified concentrations or can be prepared in the form of aqueous concentrates in which the concentration of various ingredients is considerably higher, so that the concentrates can be diluted with aqueous medium. such as water or are diluted by feeding them in an activator bath containing an activator rinse that has been in use for some time.

In accordance with the present invention, the activating rinse bath may comprise a chelator. The chelator may comprise, for example, carboxylates such as tartrates, citrates or gluconates, acetate-based complexes such as ethylenediaminetetraacetate or nitrilotriacetate, phosphates such as pentasodium triphosphate or tetrapotassium pyrophosphate, phosphonates, polycarboxylates, acids, esters or salts of any of the aforementioned, or their combinations.

The metal substrate pretreatment system of the present invention further comprises a pretreatment composition comprising zinc ions and phosphate ions. In the pretreatment composition nickel is only present, if present, in a trace amount of 5 ppm or less, based on a total weight of the composition.

[As used herein, the term "pretreatment composition" refers to a composition that, upon contact with a substrate, reacts and chemically alters the surface of the substrate and binds thereto to form a protective layer and containing phosphates of zinc, iron and/or other divalent metals known in the art.] As used herein, the term "substantially free", when used with respect to the absence of nickel, means that the nickel, if present in the bath containing the pretreatment composition, the pretreatment composition and/or the layers formed from and comprising the same and, if present, it is only present in a trace amount of 5 ppm or less , based on a total weight of the composition or layer(s), as the case may be. As used herein, the term "essentially free", when used with respect to the absence of nickel, means that nickel. , if present in the bath containing the pretreatment composition, the pretreatment composition and/or the layers formed from and comprising the same and, if present, it is only present in a trace amount of 1 ppm or less, based on a total weight of the composition or layer(s), as the case may be. As used herein, the term "completely free", when used with respect to the absence of nickel, means that nickel is absent from the bath containing the pretreatment composition, the pretreatment composition and/or the layers. formed from, and comprising the same (i.e., the bath containing the pretreatment composition, the pretreatment composition and/or the layers formed from, and comprising the same contain 0 ppm nickel, which exclude nickel derived from drag, substrate(s) and/or dissolution of the equipment.

According to the present invention, the zinc ion content of the pretreatment composition may be at least 500 ppm, based on the total weight of the pretreatment composition, such as at least 800 ppm and, in some cases, may not be. be more than 1500 ppm, based on the total weight of the pretreatment composition, such as not more than 1200 ppm. According to the present invention, the zinc ion content of the aqueous acid compositions may be from 500 ppm to 1500 ppm, based on the total weight of the pretreatment composition, such as at least 800 ppm to 1200 ppm. The source of the zinc ion may be conventional zinc ion sources, such as zinc nitrate, zinc oxide, zinc carbonate, metal zinc and the like.

According to the present invention, the phosphate content of the pretreatment composition may be at least 8000 ppm, based on the total weight of the pretreatment composition, such as at least 12000 ppm, and in some cases it may not be more of 20,000 ppm, based on the total weight of the pretreatment composition, such as not more than 14,000 ppm. According to the present invention, the phosphate content of the pretreatment composition may be 8000 ppm to 20,000 ppm, based on the total weight of the pretreatment composition, such as 12,000 ppm to 14,000 ppm. The phosphate ion source may be phosphoric acid, monosodium phosphate, disodium phosphate and the like.

The pretreatment composition of the present invention may have a pH of at least 2.5, such as at least 3.0, and in some cases no more than 5.5, such as no more than 3.5. The pretreatment composition may have a pH of 2.5 to 5.5, such as 3.0 to 3.5.

According to the present invention, the pretreatment composition further comprises an accelerator. The accelerator may be present in an amount sufficient to accelerate the formation of the zinc phosphate coating and may be present in the pretreatment composition in an amount of at least 500 ppm, based on the total weight of the pretreatment composition, such as at least 1000 ppm, such as at least 2500 ppm, and in some cases may be present in an amount of no more than 20000 ppm, based on the total weight of the pretreatment composition, such as no more than 10000 ppm, such as no more than 5000 ppm. According to the present invention, the accelerator may be present in the pretreatment composition in an amount of 500 ppm to 20,000 ppm, based on the total weight of the pretreatment composition, such as 1000 ppm to 10,000 ppm, such as 2500 ppm to 5000 ppm. The accelerator includes an oxime such as acetaldehyde oxime and acetoxime, a nitrite such as sodium nitrite and ammonium nitrite, a peroxide such as hydrogen peroxide or combinations thereof.

According to the present invention, the pretreatment composition may also comprise fluoride ions, nitrate ions and various metal ions, such as cobalt ions, calcium ions, magnesium ions, manganese ions, iron ions, copper ions and the like.

The fluoride ion may be present in the pretreatment composition in an amount of at least 100 ppm, based on the total weight of the pretreatment composition, such as at least 250 ppm, and in some cases may be present in an amount of no. more than 2500 ppm, based on the total weight of the pretreatment composition, such as not more than 1000 ppm, and in some cases may be present in an amount of 100 ppm to 2500 ppm, based on the total weight of the pretreatment composition pretreatment, such as 250 ppm to 1000 ppm.

According to the present invention, the nitrate ion may be present in the pretreatment composition in an amount of at least 1000 ppm, based on the total weight of the pretreatment composition, such as at least 2000 ppm, and in some cases may be present in an amount of no more than 10,000 ppm, based on the total weight of the pretreatment composition, such as no more than 5,000 ppm, and in some cases may be present in an amount of 1,000 ppm to 10,000 ppm, based on the total weight of the pretreatment composition, such as for example 2000 ppm to 5000 ppm.

According to the present invention, the calcium ion may be present in the pretreatment composition in an amount of at least 100 ppm, based on the total weight of the pretreatment composition, such as at least 500 ppm and, in some cases, no more than 4000 ppm, based on the total weight of the pretreatment composition, such as no more than 2500 ppm, and in some cases may be present in an amount of 100 ppm to 4000 ppm, based on the total weight of the composition pretreatment, such as 500 ppm to 2500 ppm.

According to the present invention, the manganese ion may be present in the pretreatment composition in an amount of at least 100 ppm, based on the total weight of the pretreatment composition, such as at least 200 ppm, such as at least 500 ppm, and in some cases no more than 1500 ppm, based on the total weight of the pretreatment composition, such as no more than 1000 ppm, such as no more than 800 ppm, and in some cases, in an amount of 100 ppm to 1500 ppm, based on the total weight of the pretreatment composition, such as from 200 ppm to 1000 ppm, such as from 500 ppm to 800 ppm.

According to the present invention, the iron ion may be present in the pretreatment composition in an amount of at least 5 ppm, based on the total weight of the pretreatment composition, such as at least 50 ppm and, in some cases, no more than 500 ppm, based on the total weight of the pretreatment composition, such as no more than 300 ppm, and in some cases, may be present in the pretreatment composition in an amount of 5 ppm to 500 ppm, such as from 50 ppm to 300 ppm.

According to the present invention, the copper ion may be present in the pretreatment composition in an amount of at least 1 ppm, based on the total weight of the pretreatment composition, such as at least 3 ppm and, in some cases, no more than 30 ppm, based on the total weight of the pretreatment composition, such as no more than 15 ppm, and in some cases, may be present in the pretreatment composition in an amount of 1 ppm.

The pretreatment composition of the present invention can be prepared fresh with the above-mentioned ingredients in the specified concentrations or can be prepared in the form of aqueous concentrates in which the concentration of the various ingredients is considerably higher, so that the concentrates can be diluted with aqueous medium such as water or are diluted by feeding them in a zinc phosphating composition that has been in use for some time. Typical concentrates may contain at least 10,000 ppm zinc ions, based on the total weight of the pretreatment composition concentrate, such as at least 12,000 ppm zinc ions, such as at least 16,000 ppm zinc ions, and in some cases may contain no more than 100,000 ppm of zinc ions, based on the total weight of the pretreatment composition concentrate, such as no more than 30,000 ppm of zinc ions, such as no more than 20,000 ppm of zinc ions, and in some cases may contain from 10,000 ppm to 100,000 ppm of zinc ions, based on the total weight of the pretreatment composition concentrate, such as from 12,000 ppm to 30,000 ppm of zinc ions, such as from 16,000 ppm to 20,000 ppm of zinc ions.

The metal substrate pretreatment system of the present invention can be used in a method of treating a metal substrate comprising contacting at least a portion of a surface of the substrate with the activating rinse comprising a dispersion of phosphate particles of metal having a particle size D90 of 50 to 500 nm, wherein the metal phosphate comprises divalent or trivalent metals or combinations thereof, and subsequently contacting at least a portion of the surface that has been in contact with the activator rinse with the pretreatment composition comprising zinc ions and phosphate ions, wherein in the pretreatment composition nickel is only present, if at all, in a trace amount of 5 ppm or less, based on a total weight of the composition , and wherein the pretreatment composition further comprises an accelerator, wherein the accelerator includes an oxime, a nitrite, a peroxide, or a combination thereof.

Optionally, the surface of the substrate to be treated in accordance with the methods of the present invention may be cleaned to remove grease, dirt or other foreign matter and/or rinsed before applying the activator rinse. Cleaning the substrate surface is often accomplished by employing mild or strong alkaline cleaners, such as those commercially available and conventionally used in metal pretreatment processes. Examples of alkaline cleaners suitable for use in the present invention include Chemkleen™ 163, Chemkleen™ 177, Chemkleen™ 181ALP, Chemkleen™ 490MX and Chemkleen™ 2010LP, each of which is commercially available from PPG Industries, Inc.

After cleaning, the substrate can optionally be rinsed with running water, and/or an aqueous solution of rinse aids to remove any residue. The wet substrate surface may optionally be dried, such as air dried, for example, by use of an air knife or hot air blower.

In accordance with the present invention, the activator rinse can be applied to the surface of the substrate by spraying, roller coating or dipping techniques. The activator rinse may be applied to the substrate at a temperature of, for example, 15°C to 50°C, such as 25°C to 35°C for any suitable period of time, such as at least 1 second, such as such as at least 10 seconds, such as at least 2 minutes, such as at least 5 minutes.

According to the present invention, the method of treating a metal substrate further includes contacting at least a portion of the surface that has been in contact with the activator rinse with the pretreatment composition described above to form a phosphate coating on the surface of the “activated” substrate. The pretreatment composition can be applied by spraying or immersing the activated substrate in a zinc-containing phosphate bath at a temperature typically ranging from 20°C to 75°C for 1 to 3 minutes. The bath may typically be an acid phosphate bath and may comprise iron and/or other divalent metals known in the art in addition to zinc ions, as discussed above.

Following application of the phosphate coating, the substrate may then optionally be rinsed with a chromium-containing or chromium-free solution, optionally rinsed with water, and/or optionally dried. Paint can then be applied, if desired, such as by electroplating or by conventional spray or roller coating techniques.

The present invention is also directed to a substrate treated with the pretreatment system described herein. The substrate may comprise nucleation sites formed from an activator rinse described above, and may further comprise a metal phosphate coating formed from a metal phosphate pretreatment composition described above applied on the nucleation sites formed on the least a portion of the substrate through the activator rinse. The metal phosphate coating may comprise crystals having a crystal size of at least 0.4 pm, such as at least 0.5 pm, such as at least 0.6 pm, such as at least 0.9 pm, and in some cases no greater than 4 pm, such as no greater than 2.7 pm, such as no greater than 2.5 pm, such as no greater than 2 pm. The metal phosphate coating may comprise crystals having a crystal size of 0.4 pm to 4 pm, such as 0.5 pm to 2.5 pm, such as 0.6 pm to 2 pm.

The crystal size of a phosphate coating can be determined by methods known to those skilled in the art. For example, a representative area of the panel can be selected (i.e., a coated area of approximately 1.27 cm by 1.27 cm without obvious coating defects) and an image of the representative area can be acquired at a magnification of 5000x or 10000x using the using a scanning electron microscope (SEM), such as a Tescan Vega 2 SEM. The magnification used will depend on the crystal size, as a high magnification (10000x) will be required for crystal sizes that are not distinguishable with a 5000x magnification by using an SEM. Nine to twelve evenly spaced crystals, for example ten, can be measured in each image using a computer program known to those skilled in the art, such as, for example, ImageJ (version 1.46), and the sizes of the crystals can be averaged. representative crystal to determine crystal size. One skilled in the art will recognize that there may be variations to this procedure that preserve the essential elements of microscopic imaging and the average representative crystal size.

In one example, the present invention may also be directed to an activation stage such as those used in an automobile manufacturing facility. In accordance with the present invention, the activation step comprises immersion of the substrate in a bath containing the activating rinse of the metal substrate pretreatment system described herein. In accordance with the present invention, the activator rinse is contained within the dip tank at a temperature of 15°C to 50°C. At least a portion of a surface of the substrate is subjected to the activator rinse by immersing the substrate in the activator rinse for any suitable period of time, for example, those already described above. After being immersed in the activator rinse, a portion of the activated substrate can then be subjected to a phosphating step by applying a metal phosphate pretreatment composition, for example, a zinc phosphate pretreatment composition, to the activated substrate. It should be noted, however, that prior to application of the metal phosphate pretreatment composition to the activated substrate, an additional activator rinse may be sprayed onto a portion of the activated substrate through a spray nozzle as the activated substrate is Remove from dip tank. For example, the spray nozzle could be a bank of spray nozzles that is located downstream of the dip tank. After the activated substrate leaves the dip tank and/or after an additional activator rinse is applied to the activated substrate, the activated substrate is phosphated by applying a metal phosphate pretreatment composition to the activated substrate using techniques that are known in the art such as a spray and/or immersion technique.

In accordance with the present invention, the activation step may comprise several spray nozzles that are used to apply the activator rinse bath onto at least a portion of a substrate. Disposed below the spray nozzles is a spray tank that is adapted to collect activator rinse exiting the spray nozzles and/or any excess activator rinse dripping from the surface of the activated substrate. The spray tank is connected to the spray nozzles in a manner that allows the spray nozzles to use the activator rinse that is collected in the spray tank by thereby recycling the activator rinse bath. After applying the activator rinse to at least a portion of the substrate, the activated substrate is then phosphated as described in the previous paragraph.

According to the present invention, after the substrate is contacted with the pretreatment composition, a coating composition comprising a film-forming resin can be deposited on at least a portion of the surface of the substrate that has been contacted. with the pretreatment composition. Any suitable technique may be used to deposit said coating composition on the substrate, including, for example, brush coating, dip coating, fluid coating, spray coating and the like. In some cases, however, as described in more detail below, such deposition of a coating composition may comprise an electroplating step wherein an electrodepositable composition is deposited onto the metal substrate by electrodeposition. In certain other cases, as described in more detail below, said deposition of a coating composition comprises a powder coating step. In certain other instances, the coating composition may be a liquid coating composition.

According to the present invention, 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-stable continuous film on at least one horizontal surface of a substrate upon removal of any diluent or carrier present in the composition or upon curing at room temperature or elevated temperature. Conventional film-forming resins that may be used include, without limitation, those typically used in automotive OEM coating compositions, automotive finish 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 irreversibly "solidify" upon curing or cross-linking, where the polymer chains of the polymer components are linked by covalent bonds. This property is usually associated with a cross-linking reaction of the constituents of the composition often induced, for example, by heat or radiation. The curing or cross-linking reactions can also be carried out under ambient conditions. Once cured or cross-linked, a thermosetting resin will not melt with 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, thus, can undergo liquid flow upon heating and are soluble in solvents.

As indicated above, according to the present invention, a coating composition comprising a film-forming resin can be deposited on the substrate by an electrocoating step wherein an electrodepositable composition is deposited on the metal substrate by electrodeposition. In the electrodeposition process, the treated metal substrate, which serves as the electrode, and an electrically conductive counter electrode are brought into contact with an ionic electrodepositable composition. Upon passage of an electrical current between the electrode and the counter electrode while in contact with the electrodepositable composition, an adherent film of the electrodepositable composition will be deposited in a substantially continuous manner on the metal substrate.

According to the present invention, said electrodeposition can be carried out at a constant voltage in the range of 1 volt to several thousand volts, typically between 50 and 500 volts. The current density is usually between 1.0 amperes and 15 amperes per square foot (10.8 to 161.5 amperes per square meter) and tends to decrease rapidly during the electrodeposition process, indicating the formation of a self-insulating film. keep going.

According to the present invention, the electrodepositable coating composition may comprise a resinous phase dispersed in an aqueous medium wherein the resinous phase comprises: (a) an ionic electrodepositable resin containing an active hydrogen group, and (b) an agent curing agent that has functional groups reactive with the active hydrogen groups of (a).

In accordance with the present invention, electrodepositable compositions may contain, for example, as a primary film-forming polymer, an ionic, often cationic, electrodepositable resin containing active hydrogen. A wide variety of electrodepositable film-forming resins are known and can be used in the present invention provided that the polymers are "water dispersible", that is, adapted to be solubilized, dispersed or emulsified in water. The water dispersible polymer is ionic in nature, that is, the polymer will contain anionic functional groups to impart a negative charge or may contain cationic functional groups to impart a positive charge.

Examples of film-forming resins suitable for use in anionic electrodepositable coating compositions are base-solubilized carboxylic acid-containing polymers, such as the reaction product or adduct of a drying oil or semi-dried 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 material that is further reacted with polyol. Furthermore, at least partially neutralized interpolymers of hydroxyalkyl esters of unsaturated carboxylic acids, unsaturated carboxylic acid and at least one other ethylenically unsaturated monomer are also suitable. Still another suitable electrodepositable film-forming resin comprises an alkyd-aminoplastic carrier, that is, a carrier containing an alkyd resin and an amine-aldehyde resin. Still another anionic electrodepositable resin composition comprises mixed esters of a resinous polyol, such as described in United States Patent No.

3,749,657 in col. 9, lines 1 to 75 et al. 10, lines 1 to 13. Other acid-functional polymers may also be used, such as phosphatized polyepoxide or phosphatized acrylic polymers that are known to those skilled in the art.

As mentioned above, it is often desirable for the ionic electrodepositable resin containing active hydrogen (a) to be cationic and capable of being deposited on a cathode. Examples of such cationic film-forming resins include resins containing amine salt groups, such as the acid-solubilized reaction products of polyepoxides and primary or secondary amines, such as those described in US Pat. 3,663,389; 3,984,299; 3,947,338 and 3,947,339. Often these resins containing amine salt groups are used in combination with a blocked isocyanate curing agent. The isocyanate can be completely blocked, as described in US Patent No. 3,984,299, or the isocyanate can be partially blocked and react with the main chain of the resin, as described in US Patent No. 3,984,299. 3,947,338. Furthermore, one-component compositions as described in United States Patent No. 4,134,866 and DE-OS document no. 2,707,405 can be used as a film-forming resin. In addition to the epoxy-amine reaction products, the film-forming resins may also be selected from cationic acrylic resins, such as those described in US Pat. 3,455,806 and 3,928,157.

In addition to resins containing amine salt groups, resins containing quaternary ammonium salt groups may also be used, such as those formed from the reaction of an organic polyepoxide with a tertiary amine salt as described in United States Patent Nos. 3,962,165; 3,975,346 and 4,001,101. Examples of other cationic resins are resins containing ternary sulfonium salt groups and resins containing quaternary phosphonium salt groups, such as those described in United States Patent Nos. 3,793,278 and 3,984,922, respectively. Additionally, film-forming resins that are cured by transesterification can be used, as described in European Application No. 12463. Additionally, cationic compositions prepared from Mannich bases may be used, such as described in United States Patent No. 4,134,932.

In accordance with the present invention, the resins present in the electrodepositable composition are positively charged resins containing primary and/or secondary amine groups, as described in United States Patent Nos. 3,663,389; 3,947,339 and 4,116,900. In United States Patent No. 3,947,339, a polykethymine derivative of a polyamine, such as diethylenetriamine or triethylenetetraamine, is reacted with a polyepoxide. When the reaction product is neutralized with acid and dispersed in water, free primary amine groups are generated. Furthermore, equivalent products are formed when the polyepoxide is reacted with excess polyamines, such as diethylenetriamine and triethylenetetraamine, and the excess polyamine is removed in vacuo from the reaction mixture, as described in US Patent Nos. 3,663,389 and 4,116,900.

According to the present invention, the ionic electrodepositable resin containing active hydrogen is present in the electrodepositable composition in an amount of 1 to 60 weight percent, such as 5 to 25 weight percent, based on the total weight of the electrodeposition bath.

As indicated, the resin phase of the electrodepositable composition often further comprises a curing agent adapted to react with the active hydrogen groups of the ionic electrodepositable resin. For example, both blocked organic polyisocyanate and aminoplast curing agents are suitable for use in the present invention.

Aminoplast resins can be used as the curing agent for anionic electrodeposition, they are the condensation products of amines or amides with aldehydes. Examples of suitable amine or amides are melamine, benzoguanamine, urea and similar compounds. Generally, the aldehyde used is formaldehyde, although products can be prepared from other aldehydes, such as acetaldehyde and furfural. The condensation products contain methylol groups or similar alkyl groups depending on the particular aldehyde used. Often, these methylol groups are etherified by reaction with an alcohol, such as a monohydric alcohol containing 1 to 4 carbon atoms, such as methanol, ethanol, isopropanol, and n-butanol. Aminoplast resins are commercially available from American Cyanamid Co. under the trademark CYMEL and from Monsanto Chemical Co. under the trademark RESIMENE.

Aminoplast curing agents are often used in conjunction with active hydrogen-containing anionic electrodepositable resin in amounts ranging from 5 percent to 60 weight percent, such as 20 to 40 weight percent, the percentages based on the total weight of resin solids in the electrodepositable composition. As indicated, blocked organic polyisocyanates are often used as a curing agent in cathodic electrodeposition compositions. Polyisocyanates can be completely blocked as described in US Patent No. 3,984,299 in col. 1, lines 1 to 68, col. 2 et al. 3, lines 1 to 15, or are partially blocked and reacted with the polymer backbone as described in US Patent No. 3,947,338 at col. 2, lines 65 to 68, col. 3 et al. 4, lines 1 to 30. By "blocked" it is meant that the isocyanate groups have been reacted with a compound such that the resulting blocked isocyanate group is stable for active hydrogens at room temperature but reactive with hydrogens active in the film-forming polymer at elevated temperatures, usually between 90 °C and 200 °C.

Suitable polyisocyanates include aromatic and aliphatic polyisocyanates, including cycloaliphatic polyisocyanates, and representative examples include diphenylmethane-4,4'-diisocyanate (MDI), toluene 2,4- or 2,6-diisocyanate (TDI), including mixtures of the same, p-phenylenediisocyanate, tetramethylene and hexamethylenediisocyanates, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, mixtures of phenylmethane-4,4'-diisocyanate and polymethylenepolyphenylisocyanate. Higher polyisocyanates, such as triisocyanates, may be used. An example would include triphenylmethane-4,4',4"-triisocyanate. Isocyanate prepolymers may also be used with polyols such as neopentyl glycol and trimethylolpropane and with polymeric polyols such as polycaprolactone diols and triols (NCO/OH equivalent ratio greater than 1). .

Polyisocyanate curing agents are typically used in conjunction with the active hydrogen-containing anionic electrodepositable resin in amounts ranging from 5 percent to 60 percent by weight, such as 20 percent to 50 percent by weight, the percentages based in the total weight of the resin solids in the electrodepositable composition.

The electrodepositable coating compositions described herein may in particular be in the form of an aqueous dispersion. The average particle size of the resinous phase is generally less than 1.0 gm (microns) and usually less than 0.5 gm (microns), often less than 0.15 gm (microns).

The concentration of the resin phase in the aqueous medium is often at least 1 weight percent, such as 2 to 60 weight percent, based on the total weight of the aqueous dispersion. When such coating compositions are in the form of resin concentrates, they generally have a resin solids content of 20 to 60 weight percent based on the weight of the aqueous dispersion.

The electrodepositable coating compositions described herein are often supplied as two components: (1) a transparent resin feed, generally including the ionic electrodepositable resin containing active hydrogen, i.e., the main film-forming polymer, the curing agent and any additional non-pigmented, water-dispersible components; and (2) a pigment paste, which generally includes one or more colorants (described below), a water-dispersible grinding resin that may be the same or different from the main film-forming polymer, and, optionally, additives such as humectants or dispersion aids. The electrodeposition bath components (1) and (2) are dispersed in an aqueous medium comprising water and, usually, coalescence solvents.

As mentioned above, in addition to water, the aqueous medium may contain a coalescing solvent. Useful coalescing solvents are often hydrocarbons, alcohols, esters, ethers and ketones. Coalescing solvents that can be used can be alcohols, polyols and ketones. Specific coalescence solvents include isopropanol, butanol, 2-ethylhexanol, isophorone, 2-methoxypentanone, ethylene and propylene glycol and the monoethyl, monobutyl and monohexyl ethers of ethylene glycol. The amount of coalescing solvent is generally between 0.01 and 25 percent, such as between 0.05 and 5 weight percent based on the total weight of the aqueous medium.

After deposition of the electrodepositable 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 120 to 250°C, such as 120 to 190°C, for a period of time ranging from 10 to 60 minutes. According to the invention, the thickness of the resulting film is 10 to 50 microns.

Alternatively, as mentioned above, according to the present invention, after the substrate has been contacted with the pretreatment composition, a powder coating composition can be deposited on at least a portion of the surface of the substrate that is has been brought into contact with the pretreatment composition. As used herein, “powder coating composition” refers to a coating composition that is completely free of water and/or solvent. Accordingly, the powder coating composition described herein is not synonymous of water-based and/or solvent-based coating compositions known in the art.

According to the present invention, the powder coating composition comprises (a) a film-forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. Examples of powder coating compositions that may be used in the present invention include the polyester-based ENVIROCRON line of powder coating compositions (commercially available from PPG Industries, Inc.) or epoxy-polyester hybrid powder coating compositions. . Alternative examples of powder coating compositions that may be used in the present invention include low temperature curing thermosetting powder coating compositions comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Patent No. 7,470,752, assigned to PPG Industries, Inc. .); 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 or at least one siloxane-containing resin (such as those described in United States Patent No. 7,432,333, assigned to PPG Industries, Inc.); and those comprising a solid particulate mixture of a polymer containing reactive groups having a Tg of at least 30°C (such as those described in U.S. Patent No. 6,797,387, assigned to PPG Industries, Inc.).

Suitable film-forming polymers that can be used in the powder coating composition of the present invention comprise a (poly)ester (for example, triglycidyl polyester isocyanurate), a (poly)urethane, an isocyanurate, a (poly) urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidene fluoride, or combinations thereof.

According to the present invention, the reactive functional group of the film-forming polymer of the powder coating composition comprises hydroxyl, carboxyl, isocyanate (including blocked (poly)isocyanate), primary amine, secondary amine, amide, carbamate, urea, urethane, vinyl, unsaturated ester, maleimide, fumarate, anhydride, hydroxyl alkylamide, epoxy or their combinations.

Suitable curing agents (crosslinking agents) that can be used in the powder coating composition of the present invention comprise an aminoplast resin, a polyisocyanate, a blocked polyisocyanate, a polyepoxide, a polyacid, a polyol or combinations thereof.

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

As mentioned above, the coating composition may be a liquid coating composition. As used herein, “liquid coating composition” refers to a coating composition containing a portion of water and/or solvent. Accordingly, the liquid coating composition described herein is synonymous with water- and/or solvent-based coating compositions known in the art.

As mentioned above, according to the present invention, the coating composition may be a liquid coating composition. As used herein, “liquid coating composition” refers to a coating composition containing a portion of water and/or solvent. Consequently, the liquid coating composition described herein is synonymous with water-based and solvent-based coating compositions known in the art.

In accordance with the present invention, the liquid coating composition may comprise, for example, (a) a film-forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. In other examples, the liquid coating may contain a film-forming polymer that can react with oxygen in the air or coalesce into a film upon evaporation of water and/or solvents. These film formation 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 can be used in the present invention include the SPECTRACRON® line of solvent-based coating compositions, the AQUACRON® line of water-based coating compositions, and the RAYCRON® line of UV-cured coatings. (all commercially available from PPG Industries, Inc.).

Suitable film-forming polymers that can be used in the liquid coating composition of the present invention may comprise a (poly)ester, an alkyd, a (poly)urethane, an isocyanurate, a (poly)urea, a (poly)epoxy , an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane, or its combinations.

According to the present invention, the reactive functional group of the film-forming polymer of the liquid coating composition may comprise hydroxyl, carboxyl, isocyanate (including blocked (poly)isocyanate), primary amine, secondary amine, amide, carbamate, urea , urethane, vinyl, unsaturated ester, maleimide, fumarate, anhydride, hydroxyl alkylamide, epoxy or their combinations.

Suitable curing agents (cross-linking agents) that can be used in the liquid coating composition of the present invention may comprise an aminoplast resin, a polyisocyanate, a blocked polyisocyanate, a polyepoxide, a polyacid, a polyol or combinations thereof.

Additionally, a colorant and, if desired, various additives such as surfactants, wetting agents or catalyst may be included in the coating composition (electrodepositable, powder or liquid). As used herein, the term “colorant” means any substance that imparts color and/or other opacity and/or other visual effect to the composition. The colorant may be added to the composition in any suitable form, such as discrete particles, dispersions, solutions and/or flakes. A single dye or a mixture of two or more dyes can be used.

Examples of colorants include pigments, dyes and tinctures, such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA), as well as special effect compositions. . A colorant may include, for example, a finely divided solid powder that is insoluble but wettable under the conditions of use. A dye can be organic or inorganic and can be agglomerated or non-agglomerated. Colorants may be incorporated through the use of a grinding vehicle such as an acrylic grinding vehicle, the use of which will be familiar to one skilled in the art.

Examples of pigments and pigment compositions include, but are not limited to, crude carbazole dioxazine pigment, azo, monoazo, disazo, naphthol AS, salt type (lagos), benzimidazolone, condensation, metal complex, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavantrone, pyrantrone, antantrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketo pyrrole pyrrole red ("DPPBO red"), titanium dioxide , carbon black and their mixtures. The terms "pigment" and "color filler" can be used interchangeably.

Illustrative dyes include, but are not limited to, those that are solvent and/or aqueous based such as phthalo green or blue, iron oxide, bismuth vanadate, anthraquinone, perylene, aluminum and quinacridone.

Illustrative inks include, but are not limited to, pigments dispersed in water-based or water-miscible vehicles, such as AQUA-CHEM 896 commercially available from Degussa, Inc., CHARISMA COLORANTS, and MAXITONER INDUSTRIAL COLORANTS commercially available from the Accurate Dispersions division. from Eastman Chemicals, Inc.

As indicated above, the dye may be in the form of a dispersion including, but not limited to, a nanoparticle dispersion. Nanoparticle dispersions may include one or more highly dispersed nanoparticle dyes and/or dye particles that produce a desired visible color and/or opacity and/or visual effect. Nanoparticle dispersions may include colorants such as pigments or dyes having a particle size of less than 150 nm, such as less than 70 nm or less than 30 nm. Nanoparticles can be produced by grinding organic or inorganic pigments with grinding media that have a particle size of less than 0.5 mm. Exemplary nanoparticle dispersions and methods for manufacturing them are identified in US Patent No. 6,875,800 B2. Nanoparticle dispersions can also be produced by crystallization, precipitation, gas-phase condensation, and chemical weathering (i.e., partial dissolution). To minimize reagglomeration of nanoparticles within the coating, a dispersion of resin-coated nanoparticles can be used. As used herein, a “resin-coated nanoparticle dispersion” refers to a continuous phase in which discrete “composite microparticles” comprising a nanoparticle and a resin coating on the nanoparticle are dispersed. Examples of resin-coated nanoparticle dispersions and methods for manufacturing them are identified in United States Patent Application Publication No. 2005-0287348 A1, filed on June 24, 2004, United States Provisional Application No. 60/482,167 filed June 24, 2003 and United States Patent Application No. Serial No. 11/337,062, filed Jan. 20, 2006 (U.S. Patent Application Publication No. 2006-0251896 A1).

Examples of special effect compositions that may be used include pigments and/or compositions that produce one or more appearance effects such as reflectance, pearlescence, metallic luster, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, goniochromism and/or color change. . Additional special effects compositions may provide other perceptible properties, such as opacity or texture. According to the invention, special effect compositions can produce a color change, such that the color of the coating changes when the coating is viewed from different angles. Examples of color effect compositions are identified in United States Patent No.

6,894,086. Additional color effect compositions may include transparent coated mica and/or synthetic mica, coated silica, coated alumina, a transparent liquid crystal pigment, a liquid crystal coating and/or any composition where the interference results from a differential of refractive index within the material and not due to the differential refractive index between the surface of the material and the air.

According to the invention, a photosensitive composition and/or photochromic composition can be used, which reversibly alters its color when exposed to one or more light sources. Photochromic and/or photosensitive compositions can be activated by exposure to radiation of a specified wavelength. When the composition is excited, the molecular structure changes and the altered structure exhibits a new color that is different from the original color of the composition. When radiation exposure is removed, the photochromic and/or photosensitive composition may return to a resting state, in which the original color of the composition returns. According to the invention, the photochromic and/or photosensitive composition may be colorless in an unexcited state and exhibit a color in an excited state. Complete color change may appear within milliseconds to several minutes, such as 20 seconds to 60 seconds. Examples of photochromic and/or photosensitive compositions include photochromic dyes.

According to the invention, the photosensitive composition and/or the photochromic composition can be associated with and/or at least partially linked to, such as by covalent bond, a polymer and/or polymeric materials of a polymerizable component. In contrast to some coatings in which the photosensitive composition can migrate out of the coating and crystallizes on the substrate, the photosensitive composition and/or photochromic composition that is associated with and or at least partially bonded to a polymer and or polymerizable component according to With the invention, they have minimal migration out of the coating. Examples of photosensitive compositions and/or photochromic compositions and methods for preparing them are identified in United States application no. Ser. 10/892,919 filed July 16, 2004 (United States Patent Application Publication No.

2006-0014099 A1).

In general, the pigments may be present in the coating composition in any amount sufficient to impart the desired property, visual and color effect. The colorant may comprise from 1 to 65 weight percent of the present compositions, such as from 3 to 40 weight percent or from 5 to 35 weight percent, with weight percent based on the total weight of the compositions.

In accordance with the present invention, it has been unexpectedly and surprisingly discovered that application of the activator rinse described herein to a surface of the metal substrate prior to application of the metal phosphate pretreatment composition allows the bath containing the metal phosphate pretreatment composition (and therefore the metal phosphate pretreatment composition to be applied) at a lower temperature than methods employing conventional activator rinses, such as Jernstedt-type activators or other metal phosphate activator rinses. zinc comprising metal phosphate particles having a particle size D90 greater than 10 gm. As G. W. Jernstedt discovered the beneficial effects of activating metal surfaces by treating them with a titanium-containing solution together with sodium phosphate prior to zinc phosphating, titanium-containing activator compositions are now generally called "Jernstedt-type activators." For example, according to the present invention, the phosphate bath containing the nickel-free metal phosphate pretreatment composition may be at a temperature of no more than 60°C, such as no more than 50°C, such as no exceeding 40 °C, such as not exceeding 30 °C, such as not exceeding 25 °C. According to the present invention, the temperature of the bath containing the nickel-free metal phosphate pretreatment composition may vary from 20°C to 60°C, such as from 25°C to 50°C, such as from 30°C. C to 40°C. In accordance with the present invention, application of the herein described activator rinse to a surface of the metal substrate prior to application of the nickel-free metal phosphate pretreatment composition may allow the bath containing the pretreatment composition with nickel-free metal phosphate is kept at room temperature (20 °C).

It has also been unexpectedly and surprisingly discovered that application of the activator rinse described herein to a surface of the metal substrate prior to application of the nickel-free metal phosphate pretreatment composition results in a metal phosphate coating formed on the substrate surface having a lower coating weight, smaller phosphate crystal size, greater coating coverage and improved adhesion performance compared to metal phosphate coatings formed on substrate surfaces treated with conventional activator rinses, such as such as Jemstedt type activators or activator rinses comprising metal phosphate particles having a D90 particle size of greater than 10 gm. While not wishing to be bound by any theory, it is believed that the smaller phosphate crystal sizes are the result of a more rapid reaction of the activator rinse with the substrate surface and impart more complete coverage of the substrate surface with the nucleation sites, leading to more complete coverage of the substrate surface with the subsequently applied nickel-free metal phosphate-containing pretreatment composition.

As used herein, unless otherwise indicated, a plural term may include its singular equivalent and vice versa, unless otherwise indicated. For example, although reference is made herein to "a" metal sulfate salt and "a" dispersant, a combination (i.e., a plurality) of these components may be used. Additionally, in this application, the use of "or" means "and/or" unless specifically stated otherwise, although "and/or" may be used explicitly in certain cases.

As used in the present description, "including", "containing" and similar terms are understood in the context of this application as synonyms of "comprising" and, therefore, are open-ended and do not exclude the presence of additional elements, materials, ingredients or method steps not described or mentioned. As used in the present description, "consisting of" is understood in the context of this application as excluding the presence of any element, ingredient or step. of the unspecified method. As used herein, “consisting essentially of” is understood in the context of this application to include the specified elements, materials, ingredients, solvents or method steps, where applicable, while other unspecified materials are not added. intentionally to the composition and are only present as impurities in a combined amount of less than 5% by weight based on a total weight of the composition.

As used herein, unless otherwise indicated, the term “substantially free” means that a particular material is not intentionally added to the activator rinse, and is only present as an impurity in a trace amount less than 1% by weight based on a total weight of the activator rinse. As used herein, unless otherwise indicated, the term “completely free” means that an activator rinse does not comprise a particular material, that is, the activator rinse comprises 0% by weight of said material.

For the purposes of the following detailed description, it should be understood that the invention may assume various alternative variations and sequences of steps, except where otherwise expressly specified. Furthermore, other than in any working example, or where otherwise indicated, all numbers such as those expressing values, quantities, percentages, intervals, subintervals and fractions may be read as preceded by the word “approximately,” even if The term does not appear expressly. Consequently, unless otherwise indicated, the numerical parameters set forth in the following specification and the attached claims are approximations that may vary depending on the properties to be obtained by the present invention. Although the numerical ranges and parameters setting forth the broadest scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, necessarily contains certain inherent errors as a result of the standard deviation found in their respective test measurements. 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 interpreted in light of the number of significant digits reported and by applying customary rounding techniques. . When a closed or open-ended numerical interval is described in this description, all numbers, values, quantities, percentages, subintervals and fractions within or included in the numerical interval are to be considered specifically included and pertaining to the original description hereof. application as if these numbers, values, quantities, percentages, subintervals, and fractions were explicitly written in their entirety.

The following examples illustrating the invention should not be considered as limiting the invention to its details. All parts and percentages in the examples, as well as throughout the specification, are by weight unless otherwise indicated.

Examples

Rinse activator compositions

The following activator rinse compositions were prepared as follows:

RC: RC (a Jernstedt-type activating rinse concentrate commercially available from PPG Industries, Inc., also known as VERSABOND® RC) was diluted in deionized (DI) water to a concentration of 1 g concentrate/L DI water for Prepare a bath containing the activator rinse composition.

RC30: 1.1 grams of RC30 (a zinc phosphate-based activating rinse concentrate with an average zinc phosphate particle size of approximately 1 pm and a D90 of 1-3 pm, commercially available from PPG Industries) was added. , Inc., also known as VERSABOND® 30) to 1 liter of deionized water to produce a zinc phosphate dispersion with a concentration of 1.1 g/l.

Micromedia Milled Zinc Phosphate (MMM) Activator: Micromedia Milled Zinc Phosphate (MMM) is a zinc phosphate based activator rinse that was prepared as follows: 1288.4 grams of pigment were sieved of zinc phosphate in a premixed mixture of 724 grams of deionized water, 787.7 grams of dispersant (Disperbyk-190, commercially available from BYK-Chemie GmbH) and 25.6 grams of antifoam (BYK-011, commercially available from BYK -Chemie GmbH) and mixed for 30 minutes by using a Fawcett air mixer, model LS-103A with a Cowles style blade/angle teeth type 1. This mixture was then ground in recirculation mode through a mill Eiger Mini 250 horizontal media mixer (from EMImills) containing 1.2-1.7 mm zirconia media for 8.1 minutes residence time. To 1695.7 grams of this preliminary dispersion were added 150.3 grams of deionized water. This material was then milled in recirculation mode through the Eiger mill described above, except that 0.3 mm zirconium oxide medium was used. The mixture was milled for an additional residence time of 40.1 minutes. An additional 718 grams of deionized water were added throughout the grinding process, as well as 158.3 grams of Disperbyk-190 and 2 grams of Byk-011. Several intermediate samples of the process were taken throughout the grinding, so that a final yield of 1657.3 grams was obtained. This material had a concentration of 27% by weight of zinc phosphate. 1.85 grams of the above zinc phosphate dispersion were mixed per liter of deionized water to give an activating bath with a zinc phosphate concentration of 0.5 grams per liter.

In the examples that follow, some activator baths included metal sulfates of type and in the amounts indicated in Tables 1 and 2, below.

Nickel-free phosphate pretreatment composition

A nickel-free zinc phosphate pretreatment concentrate was prepared by carefully combining the following materials and mixing well until clear:

5 gallons (18,927 liters) of a nickel-free zinc phosphate pretreatment bath were then prepared by adding the following materials in order to the deionized water:

‘ Materials available from PPG Industries, Inc.

The nickel-free zinc phosphate pretreatment bath was adjusted to a free acid value of 0.8-1.0 ml with buffer M. The free acid value was measured by titrating a 10 ml sample of the bath with a solution of 0.1 N sodium hydroxide, by using bromophenol blue as an indicator and titrating to a blue-gray end point.

Example 1

Four hot-dip galvanized panels (4 in. x 6 in., automotive grade material from Salzgitter Mannesmann Stahlservice GmbH) and four cold-rolled steel panels (10.5 cm (4.13 in.) inch), standard test panels from Chemetall GmbH) were spray cleaned with a mixture of Chemkleen 2010LP(1.25% v/v)/Chemkleen 181ALP (0.125% v/v) for 2 minutes at 49°C, followed by immersion rinse in DI water for 15 seconds and spray rinse with DI water for 15 seconds. The panels were then immersed in a bath (20°C-25°C) containing the MMM activator rinse (either with or without metal sulfate, predissolved in a minimal amount of DI water before adding to the MMM activator rinse. MMM, as shown in table 1) for 1 minute. Then, all panels were immersed in the nickel-free zinc phosphate pretreatment bath (50 °C) for 3 minutes. The panels were then rinsed by spraying with DI water for 20-30 seconds. The panels were dried with hot air using a Hi-Velocity hand dryer manufactured by Oster® (model number 078302-300-000) on high setting at a temperature of approximately 50-55°C until the panel It was dry (approximately 1-5 minutes).

For each run, one panel was used to determine the complete status of the phosphate coating. The other panel was cut in half to produce two panels each 5.08 cm x 7.62 cm (2” x 3”) and one of the middle panels was used to determine the weight of the coating and the other middle panel was used to determine the average crystal size.

The weight of the zinc phosphate coating was determined on one of the 5.08 cm x 7.62 cm (2” x 3”) panels using the weigh-strip-weigh method. The treated panels were weighed on an analytical balance with a precision of 0.1 mg. Cold rolled steel panels were immersed in a solution composed of 100 g of sodium hydroxide granules and 25 milliliters of 98% triethanolamine diluted to a total volume of 1 liter with deionized water for 1.5 minutes to dissolve the entire coating. with zinc phosphate of the panels without dissolving the substrate. Hot-dip galvanized steel panels were immersed in a solution consisting of 16 g of ammonium dichromate [(NhUhC^Owj dissolved in 1 liter of concentrated ammonium hydroxide for 2 minutes to dissolve all zinc phosphate coating on the panels. without dissolving the substrate. After the extraction procedure, the panels were rinsed thoroughly with deionized water, gently wiped with a tissue to remove any weakly adherent phosphate coating, rinsed again with deionized water, and dried with warm air using a cloth. Hi-Velocity hand dryer manufactured by Oster® (model number 078302-300-000) on high setting at a temperature of approximately 50-55°C until the panel was dry, typically 1-5 minutes. The dry panel was weighed and the weight loss was used to calculate the weight of the coating per unit area.

The average zinc phosphate crystal size was determined in 5.08 cm x 7.62 cm (2” x 3”) panels by first selecting a representative area of the panel, i.e., a coated area of approximately 1.27 0.5 inch by 0.5 inch (1.27 cm) near the center of the 2”x3” (5.08 cm x 7.62 cm) panel with no obvious coating defects, and then purchased an image at 5000x or 10000x magnification using a Tescan Vega 2 scanning electron microscope (SEM). Magnification was determined based on crystal size, with 10000x magnification being necessary for smaller crystal sizes. Nine to twelve evenly spaced crystals were measured in each image using ImageJ software (version 1.46) and the results were averaged. ImageJ software is a public domain computer program, available at http://imagej.nih.gov/ij/. More details of the method have already been described above.

After pretreatment, for each run, two panels of the treated panels were coated using Enviroprime NT, a cathodic electrocoat available from PPG Industries, Inc. and applied according to the manufacturer's instructions. Electrodeposition was carried out at 220 volts, using a 30 second ramp. The temperature of the electrodeposition bath was 32.2 °C (90 °F). The current density was 0.14 A/m2 (1.5 A/ft2) and the panels were coated at 27 coulombs to achieve a dry film thickness of 18 20 pm.

The paint adhesion of the electrocoated panels (dry adhesion and exposed adhesionF described in more detail below) was tested by cross-scratching and tape removal. For the dry adhesion test, a razor blade was used to draw eleven lines parallel and perpendicular to the length of one of the electrocoated panels. The resulting grid area of the drawn lines was 1F27 cm (0F5”) x 1F27 cm (0F5”) at 1.91 cm (0.75”) to 1.91 cm (0.75”) square. Dry adhesion was evaluated using 3M Scotch 610 tape, which adhered firmly to the scribed grid area when rubbed with fingers several times before removal. Paint loss in the scratched area was evaluated on a scale of 0 to 10F with 0 being total paint loss and 10 being no paint loss. In the automotive industry an adhesion value of 7 is considered acceptable. For the exposed adhesion test F after electrodeposition F the other panel was immersed in deionized water (40 °C) for ten days, at which time the panels were removed , towel dried and allowed to sit at room temperature for one hour before scratching and removing the tape to evaluate paint adhesion as described above.

Metal phosphate coating weight (g/m2), metal phosphate crystal size, and dry and exposed adhesion performance for the treated panels are reported in Table 1 below.

Board

As shown in Table 1, immersion of hot-dip galvanized steel panels in activator baths made of MMM activator rinse compositions that did not include a metal sulfate or that included zinc sulfate had an exposed adhesion value of zero, indicating extremely poor adhesion. In contrast, when the panels were immersed in activator baths made of activator rinse compositions that included nickel sulfate or cobalt sulfate, the exposed adhesion performance was significantly improved to a rating of 9. As noted above, an adhesion value of at least 7 is considered acceptable in the automotive industry. The inclusion of nickel sulfate or cobalt sulfate in the activator rinse composition also resulted in a decrease in coating weight and a decrease in crystal size.

Example 2

For each run shown in Table 2, “North American” hot-dip galvanized (HDG) panels (10.2 cm (4 in.) x 15.2 cm (6 in.), from ACT Test Panels) and four panels “European” HDGs (10.5 cm (4.13 in) x 15.2 cm (6 in), from Chemetall GmbH) were spray cleaned with a mixture of Chemkleen 2010LP (1.25% v/v)/Chemkleen 181 ALP (0.125% v/v) for 2 minutes at 49°C followed by immersion rinse in DI water for 15 seconds and spray rinse with DI water for 15 seconds. The panels were then immersed in a bath (20°C-25°C) containing RC, RC30, or MMM activator rinse (with or without metal sulfate, as shown in Table 1) for 1 minute. The panels were then immersed in a nickel-free zinc phosphate pretreatment bath (30°C or 50°C) for 3 minutes or in a nickel-containing zinc phosphate pretreatment bath (50°C) for 3 minutes. . The panels were then rinsed by spraying with DI water for 20-30 seconds. The panels were dried with hot air using a Hi-Velocity hand dryer manufactured by Oster® (model number 078302-300-000) on high setting at a temperature of approximately 50-55°C until the panel It was dry (approximately 1-5 minutes).

The coating weight and average crystal size of zinc phosphate were measured as described in Example 1.

Two panels were electrocoated using Enviroprime NT, a cathodic electrocoater available from PPG Industries, Inc. using the same process described in Example 1. One panel was then tested using the dry adhesion test and the other panel was electrocoated. tested by the exposed adhesion test, as described in example 1.

Coating weight (g/m2), glass size, and dry and exposed adhesion performance for the North American HDG panels are reported in Table 2 and for the treated European HDG panels are reported in Table 3.

Table 2

* CE: Comparative example

Table 3

* CE: Comparative example

The results in Tables 2 and 3 show that the inclusion of nickel sulfate or cobalt sulfate in the RC30 or MMM activator rinse results in reduced crystal size and coating weight of an applied nickel-free zinc phosphate coating subsequently compared to the use of activating rinses that do not include nickel sulfate or cobalt sulfate. Table 2 further shows that the inclusion of nickel sulfate or cobalt sulfate in an activator rinse generally improves the dry and exposed adhesion of an electrodepositable coating subsequently applied over the phosphate coating, even when the zinc phosphate pretreatment composition was applied at low temperatures.

Example 3

Comparative Example I was prepared according to Example 2 of United States Publication No.

2012/0160129A1 from Inbe. RC and composition 2A were prepared as described above.

The dispersion of comparative I was characterized as follows and compared to the activation properties of composition 2A.

X-ray diffraction of the dry solids of Comparative I showed both ZnO and zinc phosphate.

Particle size (D-i0, D50 and D90) was measured using a Mastersizer 2000 (available from Malvern Instruments, Ltd., Malvern, Worcestershire, United Kingdom). A laser beam (0.633 mm diameter, 633 nm wavelength) was directed through a scattering of particles (in deionized water to 2 3% obscuration). The light scattering of the scattering was measured (measurement parameters 25 °C, 2200 RPM, pre-measurement delay 30 seconds, background measurement 10 seconds, sample measurement 10 seconds) and the data were analyzed using the computer program (Malvern Mastersizer 2000 program, version 5.60) to generate a particle size distribution, from which particle sizes (mean, D10, D50, and D90) were determined and reported in Table 4.

Table 4.

* CE: Comparative example

For each run shown in Table 5, cold-rolled steel, electrogalvanized steel, or 6022 aluminum alloy panels (10.2 cm x 15.2 cm (4”x6”), all available from ACT, were spray cleaned Test Panels, LLC) with a mixture of Chemkleen 2010LP (1.25% v/v)/Chemkleen 181 ALP (0.125% v/v) for 2 minutes at 49°C/120F, followed by rinsing by immersion in DI water for 15 seconds and spray rinse with DI water for 15 seconds. The panels were then immersed in a bath (20°C-25°C) containing Comparative Example I or Composition 2A, as shown in Table 5, for 1 minute. Activated panels (Comparative Example I or Composition 2A) were then immersed in a zinc phosphate pretreatment bath (made from Chemfos 700AL, commercially available from PPG Industries, Inc., prepared according to instructions provided by the supplier). at a bath temperature of 25.6 °C (78 F) for 2 minutes. All panels were then rinsed by spraying with DI water for 20-30 seconds. The panels were dried with hot air using a Hi-Velocity hand dryer manufactured by Oster® (model number 078302-300-000) on high setting at a temperature of approximately 50-55°C until the panel It was dry (approximately 1-5 minutes).

For each run, one of the panels was used to determine the complete state of the phosphate coating. The other panel was cut in half to produce two panels each measuring 5.1 cm x 7.6 cm (2” x 3”) and one of the middle panels was used to determine the coating weight and the other middle panel was used to determine the average crystal size.

The complete state of the zinc phosphate coating and the weight of the coating were determined as described in Example 1. The average crystal size of zinc phosphate was determined as described in Example 1. The data are presented in the table 5, below.

Table 5.

As shown in Table 5, composition 2A provided 100% full coating state on CRS and 95% full coating state on 6022 aluminum alloy panels. In contrast, Comparative I provided only 60% % of the complete coating state in CRS and 40% of the complete coating state in 6022 aluminum alloy panels. Both composition 2A and comparative I gave 100% of the complete coating state in EG steel panels, but the expert understands that EG panels are typically 100% coated. Also as shown in Table 5, additionally, the crystal size was smaller and the weight of the coating was lower in the panels treated with composition 2A than in those treated with comparative I, regardless of the substrate.

Claims (14)

1. A metal substrate pretreatment system, comprising: a) an activating rinse for treating at least a portion of a substrate comprising a dispersion of metal phosphate particles having a particle size D90 of 50 to 500 nm, wherein the metal phosphate comprises divalent or trivalent metals or their combinations; and b) a pretreatment composition for treating at least a portion of the substrate treated with the activator rinse, comprising zinc ions and phosphate ions, wherein in the pretreatment composition nickel is only present, if present, in a trace amount of 5 ppm or less, based on a total weight of the composition, and wherein the pretreatment composition further comprises an accelerator, wherein the accelerator includes an oxime, a nitrite, a peroxide or a combination thereof; wherein the D90 particle size determined according to the method described in the specification refers to a volume-weighted particle distribution in which 90% of the particles have a diameter smaller than the D90 value. 2. The pretreatment system according to claim 1, wherein the D90 particle size is measured from a sample of the activator rinse that has been sonicated. 3. The pretreatment system according to claim 1 or 2, wherein the activator rinse further comprises a metal sulfate salt, wherein the sulfate of the metal sulfate salt is present in an amount of 5 ppm to 5000 ppm based on total weight of activator rinse. 4. The pretreatment system of any of the preceding claims, wherein the divalent or trivalent metals of the metal phosphate in the activator rinse comprise zinc, iron or a combination thereof. 5. The pretreatment system of any of the preceding claims, wherein the activating rinse comprises a dispersant comprising nonionic polymers. 6. The pretreatment system of any of the preceding claims, wherein in the activator rinse the ionic dispersants are present in an amount of less than 1% by weight, based on the total weight of the activator rinse. 7. The pretreatment system according to claim 3, wherein the metal of the metal sulfate salt comprises nickel, copper, zinc, iron, magnesium, cobalt, aluminum or their combinations, preferably nickel, cobalt or their combinations. 8. A method of treating a metal substrate comprising: a) contacting at least a portion of a surface of the substrate with an activating rinse as defined in any of claims 1 to 7; and b) contacting at least a portion of the surface that has been in contact with the activating rinse with a pretreatment composition comprising zinc ions and phosphate ions, wherein in the pretreatment composition nickel is only present, if present , in a trace amount of 5 ppm or less, based on a total weight of the composition, and wherein the pretreatment composition further comprises an accelerator, wherein the accelerator includes an oxime, a nitrite, a peroxide or a combination thereof . 9. The method of claim 8, wherein contacting the pretreatment composition comprises immersing the substrate in a bath comprising the pretreatment composition, wherein the temperature of the bath is from 20°C to 60°C. 10. A metal substrate treated with the pretreatment system of any of claims 1 to 7, preferably in a method according to any of claims 8 or 9. 11. The substrate according to claim 10, wherein the phosphate coating formed from the pretreatment composition comprises metal/zinc phosphate crystals having an average crystal size of 0.4 pm to 2 gm, preferably 0.7 gm to 1.5 gm measured with a scanning electron microscope at a magnification of 10000x. 12. The substrate according to claims 10 or 11, wherein the phosphate coating has a weight of 4.4 gIm2 or less and an exposed adhesion value of 6 or greater. 13. The substrate of any of claims 10 to 12, wherein the phosphate coating has a weight of 0.5 to 4 g/m2 measured by the weigh-strip-weigh method. 14. The substrate of any of claims 10 to 13, wherein the substrate further comprises an electrodeposited layer.