MXPA98003016A - Post-rinsing composition without chrome for metallic substrates fosfata - Google Patents

Abstract

The composition of a chromium-free post-rinse composition for treating phosphatized metal substrates is disclosed. The composition comprises the reaction product of a functional epoxy material containing at least two epoxy groups, and an alkanolamine or a mixture of alkanolamines. The composition further comprises a metal ion group IV-Bo a mixture of the group of metal ions IV-B. A chrome-free post-rinse concentrate is also provided, a process for treating a phosphatized metal substrate, which comprises contacting said phosphatized metal substrate with the chromium-free post-rinse composition described above, and the coated article prepared by means of this process.

Description

CHROME-FREE POST-RINSING COMPOSITION FOR METALLIC PHOSPHATE SUBSTRATES BACKGROUND OF THE INVENTION The present invention relates to chromium-free passivating compositions employed as post-rinses in the preparation of phosphate-coated metal substrates. Post-rinses or sealants improve the corrosion resistance of metal substrates, particularly those that have been pretreated with phosphate conversion coatings. In the past many post-rinse compositions contained chromic acid. To further develop post-rinse technology considering the environmental and safety fields from the point of view of the formulation rather than from the process point of view, it is desirable to replace the post-rinses with chromic acid by post-rinses without chromium. The post-rinse technology has used some solubilized metal ions other than chromium to improve the corrosion resistance of phosphate metal substrates as shown in U.S. Patent Nos. 3,966,502 and 4,132,572. U.S. Patent No. 3,966,502. These metal ions may include: water-soluble zirconium salt, and fluorophosphate salt or a mixture of fluorophosphate salts. The technology has also used in rinse compositions organic, polymeric or nitrogen-containing materials such as vegetable tannin, poly-4-vinylphenol or its derivative, and a derivative of a polyalkenylphenol, all of which are used in conjunction with other specific components. Rinsing compositions such as those shown in U.S. Patent Nos. 3,975,214, 4. 376,000 and 4,517,028, respectively, improve the corrosion resistance of phosphate-coated metal substrates.

Several examples of rinse compositions with various specific combinations of components are available in the art. For example, the rinse composition of U.S. Patent No. 3,615,895 has an aqueous solution of alkali metal silicate prepared from the metal oxide of sodium or potassium; and a water-soluble quaternary nitrogen compound having at least one non-hydroxylated alkyl group. Another example of an aqueous rinse composition is described in U.S. Patent No. 3,912,548 having ammonium carbonate and zirconium and ammonium fluorozirconate; and polyacrylic acid, esters and their salts. U.S. Patent No. 4,110,129 discloses an aqueous rinse composition with titanium ion and an adjuvant material selected from the group consisting of phosphoric acid, phytic acid, tannin, the salts or esters of the foregoing, and hydrogen peroxide. U.S. Patent No. 4,457,790 discloses a rinse composition that includes a metal ion selected from the group consisting of titanium, hafnium and zirconium and their mixture; and a polymeric material that is a derivative of a polyalkenylphenol. Also U.S. Patent No. 5,209,788 discloses a method of treating metal substrates with an aqueous rinse composition that includes a compound of the Group IV-B metals of the Periodic Table of Elements; and an amino acid or an amino alcohol. Also in GB 1,486,820, which is considered equivalent to FR-A-2255383, a surface treatment of metals is described. This coating gives better corrosion resistance and good adhesion to paints by applying an aqueous solution, dispersion or emulsion of a water-soluble titanium compound and from 0.1 to 12% by weight of a resin. The resin is chosen from vinyl and acrylic polymers and copolymers, polyurethanes, polyesters, epoxies and rubbers. In U.S. Patent 4,775,600, metals are coated with separate films of zinc or its alloy, chromate, and a resin composition as described. This patent is considered equivalent to FR-A-2604729. The resin composition is a base resin obtained by adding one or more basic nitrogen atoms and two primary hydroxyl groups to terminals of an epoxy resin and a polyisocyanate compound. Many of the chrome-free rinses previously used or described in post-rinsing technology do not achieve the performance of chromic acid rinses. The present invention provides a new chromium-free post-rinse composition that can more closely match the performance of chromic acid rinses on commercially popular substrates. COMPENDIUM OF THE INVENTION According to the present invention, a chromium-free post-rinse composition for treating phosphate-containing metal substrates is provided which includes: a) the reaction product of an epoxy-functional material having at least two epoxy groups; and an alkanolamine, or a mixture of alkanolamines; and) a metal ion of Group IV-B of the Periodic Table of Elements, or a mixture of such metal ions of Group IV-B.

A chrome-free post-rinse concentrate is also provided for preparing the post-rinse composition without aqueous chromium by dilution with water. Another aspect of the invention is a process for treating phosphatized metal substrates which includes contacting them with the chromium-free post-rinse composition described above; and the coated article prepared by this procedure. DETAILED DESCRIPTION The present invention provides chrome-free post-rinse compositions prepared from polymeric epoxy compounds with the metal ion of Group IVB to improve the corrosion resistance of phosphate-coated metal substrates, and can achieve the performance of chromic acid rinses in resistance tests. the corrosion. While not intending to be limited by any particular theory, it is believed that various theories can be applied to the present invention. It is believed that for species of approximately equal molecular weights, the reaction product improves adhesion when the epoxy functional material contains more than two epoxy groups, and contains aromatic or cycloaliphatic functionality. In addition, epoxy-functional materials should be relatively more hydrophobic than hydrophilic in nature. It is believed that adhesion to phosphate metal substrates improves when aromatic or cycloaliphatic groups are present in the epoxy containing materials and when there are increasing amounts of epoxy groups. It is also theorized that hydrophobic materials are less readily removed by rinsing than hydrophilic materials by rinsing phosphatized metal substrates treated with the chromium-free post-rinse compositions of the present invention with deionized water prior to drying the treated substrates. Among the epoxy-functional materials that can be used are polyglycidyl ethers of alcohols or phenols; epoxy-functional acrylic polymers; polyglycidyl esters of polycarboxylic acids; epoxidized oils; epoxidized melamines; and similar epoxy-functional materials known to those skilled in the art. The polyglycidyl ethers of alcohols or phenols are prepared from aliphatic alcohols or, preferably, polyhydric phenols. Examples of suitable aliphatic alcohols are ethylene glycol; diethylene glycol; pentaerythritol; trimethylol propane; 1,4-butylene glycol; and analogues. Mixtures of alcohols are also suitable. Examples of suitable polyhydric phenols include aromatic species such as 2,2-bis (4-hydroxyphenyl) propane (bisphenol A); 3-hydroxyphenol (resorcinol); and analogues. Cycloaliphatic polyols, for example 1,2-cyclohexanediol; 1,2-bis (hydroxymethyl) cyclohexane; hydrogenated bisphenol A and the like. Also suitable are novolak resins, ie, resinous reaction products of epichlorohydrin with phenol-formaldehyde condensates. These epoxidized novolaks can contain at least two epoxy groups per molecule, and epoxidized novolaks having up to 7 or more epoxy groups are commercially available. In the preferred embodiment of the invention, the epoxy functional material is the diglycidyl ether of bisphenol A, marketed by Shell Chemical Company as EPON® 828 epoxy resin, which is a reaction product of epichlorohydrin and 2,2-bis (4-) hydroxyphenyl) propane (bisphenol A) having a molecular weight of about 400, and an equivalent epoxide (ASTM D-1652) of about 185-192. Examples of epoxy-functional acrylic polymers include copolymers of ethylenically unsaturated acrylic monomers having at least one epoxy group. Examples include glycidyl methacrylate; glycidyl acrylate; allyl glycidyl ether, (3,4-epoxycyclohexyl) methyl acrylate and analogous monoepoxy monomers known to those skilled in the art. Mixtures of these monomers are also suitable. Typically, other polymerizable ethylenically unsaturated monomers are made to bond with the epoxy-functional acrylic monomers. This serves to prevent gelation during the polymerization, or to modify the properties of the epoxy-functional acrylic polymer. Examples of other monomers that could be used include: vinyl aromatics such as styrene and vinyl toluene; nitriles such as acrylonitrile and methacrylonitrile; vinyl and vinylidene halides such as vinyl chloride and vinylidene fluoride and vinyl esters such as vinyl acetate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxymethyl methacrylate; hydroxypropyl acrylate; hydroxypropyl methacrylate; butyl acrylate; 2-hydroxypropyl methacrylate; allyl glycidyl ether and the like, including mixtures thereof. Generally, any amount of these other monomers can be used, provided that the resulting polymer contains at least two epoxy groups. The polyglycidyl esters of polycarboxylic acids are formed from the reaction of polycarboxylic acids with an epihaiohydrin such as epichlorohydrin. The polycarboxylic acid can be formed by the reaction of alcohols with anhydrides using methods known to those skilled in the art. Preferably, the alcohol is a diol, or any higher functional polyalcohol. For example, trimethylol propane or pentaerythritol could react with phthalic anhydride or hexahydrophthalic anhydride to produce a polycarboxylic acid which could also react with epichlorohydrin to produce a polyglycidyl ester containing aromatic or cycloaliphatic functionality. It is also possible to use drying oils that have been epoxidized. Examples of suitable drying oils include linseed oil, tung oil and the like. Preferably, the oils have an equivalent epoxy weight of up to about 400, more preferably from about 150 to about 300, as measured by perchloric acid titration using methyl violet as an indicator; and a carbon chain length of less than about 30 carbon atoms, preferably less than about 20 carbon atoms. Such materials are marketed by Witco Chemical Company under the trade name DRAPEX®. These materials include epoxidized soya bean oils such as epoxidized tallow 2-ethylhexyl carboxylate, epoxidized fatty oils may have 8 to 22 carbon atoms as the resin oil for epoxidized 2-ethylhexyl-tallow oil and cocoamides such as cocodiethanolamide. An example of a preferred material is DRAPEX 10.4, which is an epoxidized linseed oil with an epoxy equivalent weight of 172 and a carbon chain length of about 18, as reported by the manufacturer. Also suitable are epoxidized aminoplast resins having at least two epoxy groups. Suitable epoxy resins include those defined by the following structural formula: O O II / \ Aminoplast-NH-C-RpCH-CH2 where R: represents (CH2) m2, where m2 is an integer of the order of 1 to 2, preferably 1. The aminoplast can be any thermostable resin prepared from the reaction of a amine with an aldehyde, such as melamine resins and urea-formaldehyde resin. An example of a preferred material is an epoxidized melamine resin with an average functionality of six, marketed by Monsanto Company as photostable epoxy LSE-120. Also the mixed aliphatic-aromatic epoxy resins which may be used with the present invention are prepared by the known reaction of a bis (hydroxy-aromatic) alkane or a tetrakis alkane (hydroxyaromatic) with a substituted halogenoaliphatic epoxide in the presence of a base, such as, for example, sodium hydroxide or potassium hydroxide. After removing the hydrogen halide under these conditions, the aliphatic epoxide group is coupled to the aromatic nucleus by an ether linkage. The epoxide groups are then condensed with the hydroxyl groups to form polymer molecules. In place of epichlorohydrin, halogen-substituted aliphatic epoxies containing about 4 or more carbon atoms, generally about 4 to about 20 carbon atoms, can be used. Epichlorohydrin is the material chosen because of its commercial availability. Mixtures of epoxy-functional materials representing all the classes described above can also be used. The epoxy-functional material is reacted with an alkanolamine, or a mixture of alkanolamines. Primary or secondary alkanolamines, or mixtures thereof, are preferably used. Tertiary alkanolamines or mixtures thereof are also suitable, but the reaction conditions differ when these materials are used. Consequently, tertiary alkanolamines are not typically mixed with primary or secondary alkanolamines. Preferred alkanolamines have alkanol groups containing less than about 20 carbon atoms, more preferably, less than about 10 carbon atoms. Examples include methylethanolamine; ethyleneethane-lamellar, diethanolamine, methyliso-propanolamine, ethyl isopro-panolamine, diisopropanolamine, monoethanolamine, and diisopropanolamine and the like. Particularly preferred is diet-nolamine. If tertiary alkanolamines are to be used, it is preferred that they contain two methyl groups. An example of a suitable material is dimethylethanolamine, which is the preferred tertiary alkane-sheet. The epoxy functional material and the alkanolamines are reacted in an equivalent ratio of from about 5: 1 to about 1: 4, preferably from about 2: 1 to about 1: 2. The epoxy-functional material and alkanolamines can be coreacted by any of the methods known to those skilled in the art of polymer synthesis, including solution polymerization, emulsion, suspension or dispersion techniques. In the simplest cases, the alkanolamine is added to the epoxy-functional material at a controlled rate, and they are simply heated together, usually with some diluent, at a controlled temperature. Preferably the reaction is carried out under a nitrogen blanket or other method known to those skilled in the art to reduce the presence of oxygen during the reaction. The diluent serves to reduce the viscosity of the reaction mixture. Preferred diluents are organic solvents dispersible in water. Examples include alcohols with up to about eight carbon atoms, such as methanol or isopropanol and the like; or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol, or propylene glycol and the like. Glycol ethers are preferred. Water is also a suitable diluent. Other suitable diluents include unreactive oligomeric or polymeric materials with a viscosity in the range of about 20 centipoise to about 1,000 centipoise, measured with a Brookfield viscometer at about 22 ° C (72 ° F); and a vitreous transition temperature less than about 35 ° C, as measured by any of the common thermal analytical methods known to those skilled in the art. Examples include plasticizers such as tributyl phosphate, dibutyl maleate, butylbenzyl phthalate and the like known to those skilled in the art; and silane compounds such as vinyl trimethoxy silane, gamma-methacryloxypropyl trimethoxy silane and the like known to those skilled in the art. Also suitable are mixtures of any of these alternative diluents, water, or organic solvents. If a tertiary alkanolamine is used, a quaternary ammonium compound is formed. In this case, the usual practice is to add all the raw materials to the reaction vessel at one time and heat them together, generally with some diluent, at a controlled temperature. Typically, some acid is present, which serves to ensure that a quaternary ammonium salt is formed in place of a quaternary ammonium oxide. Examples of suitable acids are carboxylic acids such as lactic acid, citric acid, adipic acid and the like. Acetic acid is preferred. Quaternary ammonium salts are preferred because they are more easily dispersed in water, and because they produce an aqueous dispersion with a pH at or near the desired band. In contrast, if a quaternary ammonium oxide is prepared, it can then be converted to a quaternary ammonium salt with the addition of acid. The reaction product of the epoxy-functional material and the alkanolamines described above is referred to below and in the claims appended to this specification "Epoxy Reaction Product". The molecular weight of the epoxy reaction product is limited only by its dispersibility in the other materials that make up the post-rinse composition without chromium. The dispersibility of the epoxy reaction product is determined, in part, by the nature of the epoxy-functional material, the nature of the alkanolamine, and the equivalent ratio in which both react. Typically, the epoxy reaction product has a number average molecular weight of up to about 1500, as measured by gel permeation chromatography using polystyrene as a standard. Optionally, the epoxy reaction product can be neutralized to promote good dispersion in an aqueous medium. Typically, this is done by adding some acid. Examples of suitable neutralizing acids include lactic acid, phosphoric acid, acetic acid and the like known to those skilled in the art. The epoxy reaction product is present in the chromium-free post-rinse composition at a level of at least about 100 ppm, preferably, from about 400 ppm to about 1400 ppm, based on the concentration in the solids weight of the epoxy reaction product over the total weight of the post-rinse composition without chromium. A metal ion of Group IV-B or a mixture of metal ions of Group IV-B is also present in the chromium-free post-rinse composition. The metals of Group IV-B are defined by the Periodic Table of CAS Elements which is set out, for example, in the Handbook of Chemistry and Physics, 63rd edition (1983). The group includes zirconium, titanium and hafnium. Zirconium is preferred. Typically, the metal ions of Group IV-B are added in the form of metal salts or acids because in these forms, the metal ions are water-soluble. For example, zirconium ions may be added in the form of alkali metals or ammonium fluorozirconates, zirconium carboxylates or zirconium hydroxycarboxylates. Specific examples include zirconium acetate, zirconium ammonium glycolate and analogous materials known to those skilled in the art. Fluorozirconic acid is preferred. If titanium is to be used as the metal ion of Group IV-B, it is preferably added as fluorotitanic acid. Because of its relative expense, hafnium is not preferred. The metal ions of Group IV-B are added at a level of up to about 2,000 ppm. If zirconium is to be used, the preferred level is from about 75 ppm to about 225 ppm; if titanium is to be used, the preferred level is from about 35 ppm to about 125 ppm; and if hafnium is to be used, the preferred level is from about 150 ppm to about 500 ppm. The concentrations are based on the weight of the metal ion on the weight of the post-rinse composition without chromium, and "ppm" means parts per million. Optionally, other metal ions could be present in the chromium-free post-rinse composition as non-essential ingredients, for example, zinc, iron, manganese, nickel, aluminum, cobalt, calcium, sodium, potassium or mixtures thereof. These metal ions can be present from the addition of compounds known to those skilled in the art to obtain such metal ions in non-interfering form in aqueous solutions. Water-soluble or water-dispersible oils and bases are typically used to adjust the pH of the chromium-free post-rinse composition to a level of from about 3.5 to about 5.5, preferably from about 4.0 to about 4.7. Suitable acids include mineral acids such as hydrofluoric acid, fluoroboric acid, fluorosilicic acid, phosphoric acid, or mixtures thereof; or organic acids such as lactic acid, acetic acid, hydroxyacetic acid, citric acid, or mixtures thereof. Mixtures of mineral acids and organic acids are also suitable. Nitric acid is preferred. Suitable bases include inorganic metal salts such as sodium hydroxide or potassium hydroxide, or mixtures of inorganic metal salts. Nitrogen-soluble or water-dispersible compounds containing nitrogen are also suitable bases. Examples include ammonia; or amines such as triethylamine, methyl ethyl amine, or diisopropanolamine; or its mixtures. Mixtures of inorganic metal salts and nitrogen-containing compounds are also suitable. Sodium hydroxide is preferred. Other optional materials that could be present include organic solvents dispersible in water, for example alcohols with up to about eight carbon atoms such as methanol, isopropanol and the like known to those skilled in the art; or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol, or propylene glycol and the like known to those skilled in the art. When present, organic solvents dispersible in water are typically used at a level of up to about ten percent, based on the percentage in volume of solvent over the total volume of the chromium-free post-rinse composition. The chromium-free post-rinse composition may also optionally contain surfactants that function as defoamers or as adjuvants to improve substrate wetting. Anionic, cationic, amphoteric or nonionic surfactants can be used. Mixtures of these materials are also suitable, provided there is no incompatibility. In other words, anionic and cationic surfactants are not typically mixed. The nonionic surfactants are preferred. Examples of suitable anionic surfactants include lauryl sulfate and sodium; ammonium nonylphenoxy (polyethoxy) 6_60 sulfonate; and analogs known to those skilled in the art. Examples of suitable cationic surfactants include tetramethylammonium chloride; condensates of ethylene oxide of cocoamines; and analogs known to those skilled in the art. Examples of suitable amphoteric surfactants include disodium N-lauryl ammonium propionate; sodium salts of coconut derivatives of dicarboxylic acid; betaine compounds such as lauryl betaine; and analogs known to those skilled in the art.

Examples of the preferred nonionic surfactants include nonylphenoxy (polyethoxy) 6-60 ethanol; ethylene oxide derivatives of long chain acids; condensates of ethylene oxide of long chain alcohols and the like. Two nonionic surfactants which are particularly preferred for use as defoamers are ADVANTAGE® DR285 and SURFYNOL® DF110L. The first is polypropylene glycol that can be purchased from the Hercules Chemical Company market. SURFYNOL® DF110L, is a higher molecular weight liquid inert acetylene polyethylene oxide surfactant with a hydrophilic-lipophilic balance (HLB) of 3.0 that can be purchased from Air Products & Chemicals, Inc. Generally, these surfactant materials with defoaming functionality are used at levels of up to about one percent, preferably up to about 0.10%; and wetting adjuvants may optionally be used at levels of up to about two percent, preferably up to about 0.5%. The percentages are based on the volume of surfantant on the total volume of the post-rinse composition without chromium. The chromium-free post-rinse composition of the present invention is prepared by diluting the epoxy reaction product described above and other ingredients to be used in water with gentle agitation. Deionized water is preferably used. Alternatively, first a chrome-free post-rinse concentrate can be prepared. Typically, this is done by premixing all the ingredients using little water or no water. The concentrate can be stored until just before application, when diluted with water. In the preferred embodiment, the chromium-free post-rinse composition is prepared from the epoxy reaction product of EPON 828 and diethanolamine, and is present at a level from about 400 ppm to about 1400 ppm, based on the level in the weight of solids of the epoxy reaction product on the total weight of the post-rinse composition without chromium. Zirconium ions, added as fluorozirconic acid, are present at a level of about 75 ppm to about 225 ppm, based on the level in the total weight of the chromium-free post-rinse composition. Surf SURFYNOL® DF110L is used as a defoamer at approximately 0.1% volume / volume. The monomethyl ether of dipropylene glycol is also present at a level of up to about 1% volume / volume. Also in the preferred embodiment, the pH of the chromium-free post-rinse composition is adjusted to about 4.0 to 4.7 with aqueous solutions of nitric acid and sodium hydroxide. A material representing the preferred embodiment is represented in the following example 1.

Another aspect of the present invention is a process for treating phosphate metal substrates by contacting them with the chromium-free post-rinse composition described above. The chromium-free post-rinse of the present invention is suitable for treating phosphate layers of all types known to those skilled in the art which can be formed into metals, in particular steel, for example, cold-rolled steel, galvanized metal-coated hot, electrogalvanized metal, galvaneal, steel plated with a zinc alloy, aluminized steel, zinc, zinc alloys, aluminum and aluminum alloy substrates. Suitable phosphate conversion coatings that are present in these substrates are generally some of those known to those skilled in the art. For example, among others, zinc phosphate, iron phosphate, manganese phosphate, calcium phosphate, magnesium phosphate, nickel phosphate, cobalt phosphate, zinc-iron phosphate, zinc-manganese phosphate, zinc-nickel phosphate, zinc-calcium phosphate, zinc-nickel-manganese phosphate, and other types of layers, which contain one or more polyvalent cations. Generally, the most pronounced effect can be observed when using cold rolled steel to which an iron phosphate conversion coating has been applied. Other phosphate layers such as those formed by low zinc phosphating processes can be used. Such conversion coatings of iron phosphate or low zinc phosphate can be with or without the addition of other cations, such as Mn, Ni, Co and Mg. The phosphate conversion coating processes known to those skilled in the art are suitable for preparing the phosphatized metal substrate to which the rinse solution of the present invention can be applied. Generally these processes have numerous steps depending on the composition of the substrate and the subsequent coatings to be applied to the treated substrate with rinsing. Typically, in conversion coating processes there may be two to nine steps. For example, a five-step procedure may include cleaning the metal, rinsing with water, coating with a conversion coating, rinsing with water, and rinsing with a post-rinse formulation. Such a procedure can be altered by the addition of steps and / or the addition of several components to one or several steps to reduce the number of steps. For example, additional rinse steps can be used between chemical treatment steps for treating substrates with complex shapes and / or surfactants can be used in the conversion coating step to perform both cleaning and coating in the same step. Examples of such multi-step processes are iron phosphating generally with five steps and zinc phosphating generally with a minimum of six steps. After producing the conversion layer, the excess treatment solution of the surface can be removed as much as possible. This can be done, for example, by drip drying, compressing, draining or rinsing with water or an aqueous solution which can be adjusted so that it is acidic, for example, with an inorganic or organic acid (hydrofluoric acid, boric acid, nitric acid, formic acid, acetic acid, etc.). After the formation of the conversion layer, the metal surface thus treated is ready for the rinsing step. The chromium-free post-rinse composition can be applied by various techniques, such as bathing, dipping, spraying, flooding, or rolling, known to those skilled in the art of metal pretreatment. The rinsing time should be so long as to ensure sufficient wetting of the phosphatized metal substrate. Typically, the rinsing time is from about five seconds to about ten minutes, preferably from about 15 seconds to about one minute. The rinse is typically applied at a temperature from about 5 ° C to about 100 ° C, preferably from about 20 ° C to about 60 ° C. Generally, a rinse with water is applied after applying the chromium-free post-rinse composition. Deionized water is preferably used. Typically, the treated metal substrate is at this point ready for electrodeposition coating of a primer or additional layers of coatings. Alternatively, the treated metal substrate can be dried, by air drying or by forced drying. Typically, a protective or decorative coating or paint is applied to the phosphatized metal substrate after being treated as set forth above. The invention illustrates the following non-limiting examples. EXAMPLES According to the present invention, the following examples show the preparation of various post-rinsing compositions without chromium and their application to phosphate-coated metal substrates. For comparison purposes, deionized water, post-rinse compositions containing chromium, and chromium-free post-rinse compositions representing the prior art to phosphate-coated metal substrates are also applied. In all the examples, the ambient temperature was approximately 20-30 ° C. The weight percentage of solids was determined at 110 ° C for one hour. The acidity index or milliequivalents of acid were measured by titration with methanolic potassium hydroxide using phenolphthalein as an indicator. The milliequivalents of base, nitrogen or quaternary ammonium were measured by titration with aqueous hydrochloric acid using methyl violet as an indicator. The pH was measured at room temperature using a Digital Ionalyzer model # 501, marketed by Orion Research. EXAMPLE 1 PREPARATION OF THE POST-RINSING COMPOSITION WITHOUT PREFERRED CHROME First, an aromatic epoxy functional material was reacted with diethanolamine in an equivalent ratio of 1: 2. The following materials were used: 1 The diglycidyl ether of bisphenol A, marketed by Shell Chemical Company. 2 Propylene glycol monomethyl ether, marketed by the Dow Chemical Company. EPON 828 and DOWANOL PM were added to a two-liter round bottom flask equipped with a nitrogen spray line. The mixture was flushed with nitrogen for five minutes, then the spray line was removed and a stopper was placed in the flask. The reaction mixture was heated to 50 ° C, then the diethanolamine was added. There was an exotherm that raised the temperature to 92 ° C after 30 minutes. The reaction mixture was then heated to 100 ° C and maintained for two hours. The reaction mixture was then cooled and filtered to obtain an epoxy reaction product at 51.16 weight percent solids. The milliequivalents of nitrogen were measured at 1,668. A chromium-free post-rinse composition of the following materials was prepared: The composition was prepared by adding the reaction product and fluorozirconic acid to a portion of tap water with stirring. We used enough tap water to increase the volume to 19 liters. The pH was then adjusted to a final value of 4.57 using 10 ml of 1.5 molar nitric acid. EXAMPLES 2-8 Additional examples of reaction product formation are set forth in Table I, where the method for the preparation of the reaction product was similar to that of Example 1 except that observed herein. The reaction products were formulated to post-rinse compositions without chromium. In Examples 2-4, the reaction products were of an aromatic epoxy and several alkanolamines including: methylethanolamine, diethanolamine, and monoethanolamine. In Examples 5-8, the reaction products were diethanolamine and various epoxy materials including: aliphatic epoxy prepared from a drying oil, aliphatic epoxy prepared from a triol, aromatic epoxy prepared from an epoxidized melamine. In Table I below the temperature 1 and the temperature 2 are, respectively, the temperature at which the mixture of epoxy material, solvent, and deionized water, if any, and the temperature after the addition of the alkanolamine with the exotherm after the indicated period of time. With respect to Example 3, after the exotherm by the addition of the alkanolamine, a sample of one gram of the reaction mixture diluted in 10 grams of deionized water was clear, but difficult to disperse. The reaction mixture was cooled to 100 ° C and maintained for two and a half hours, at which time a one gram sample of the reaction mixture was diluted in 10 grams of deionized water and was clear and easily dispersed. A second portion of deionized water was added. The reaction mixture was then cooled and filtered to yield a reaction product at 46.78 weight percent solids. The milliequivalents of acid were measured at 0; the base milliequivalents were measured at 1,974; and the quaternary hydroxide milliequivalents were measured at 0.420. With respect to examples 4, 5, 6, 7 and 8, the monoethanolamine or diethanolamine and the first portion of DOWANOL PM were added to a two-liter round bottom flask equipped with a nitrogen spray line (one liter in the example 4). The mixture was flushed with nitrogen for five minutes, then the spray line was removed and a stopper was placed in the flask. The reaction mixture was heated to 100 ° C, then the EPON 828 or EPONEX 1511 or DRAPEX 10.4 or modifier HELOXY 44 or LSE 120 and the second portion of DOWANOL PM were added continuously in two hours. There was an exotherm that raised the temperature to 120 ° C in 50 minutes. The reaction mixture was cooled to 100 ° C during the remaining hour of feeding. After the second charge was completely added, the reaction mixture was held for an additional two hours at 100 ° C. The reaction mixture was then cooled and filtered to obtain a reaction product. With respect to example 6, after heating at 100 ° C for three hours after adding the second charge, the equivalent weight of epoxy was measured at 517. The reaction mixture was heated to 120 ° C and maintained for an additional two hours, at which time the epoxy equivalent weight was measured at 561. After another hour at 120 ° C, the reaction mixture was heated to 140 ° C and maintained for an additional ten hours, at which time the epoxy equivalent weight was measured at 857 The reaction mixture was then cooled and filtered to obtain a reaction product.

TABLE I: PREPARATION OF THE EPOXY REACTION PRODUCT 1 An epoxidized linseed oil with an epoxy equivalent weight of 172 and a carbon chain length of approximately 18, marketed by Witco Chemical Company. 2 Trimethylol ether trimethylolethane, marketed by Shell Chemical Company. 3 The reaction mixture was heated to 100 ° C, then the HELOXY modifier 44 and the second portion of DOWANOL PM were added continuously in two hours. The temperature was maintained at 100 ° C for two additional hours, then the reaction mixture was cooled and filtered. 4 An epoxidized melamine, marketed by Monsanto Company. The reaction mixture was heated to 100 ° C, then the LSE-100 and the second portion of DOWANOL PM were added continuously in two hours. 6 EPON 828 hydrogenated, marketed by Shell Chemical Company. meq N2 = milliequivalents of nitrogen. The reaction products of Table I were formulated into rinse concentrates and / or compositions as indicated in Table II where the method of preparation was similar to that of Example 1 except where noted. Nitric acid or nitric acid and one molar sodium hydroxide were used to adjust the pH to the indicated value. With respect to Examples 3, 5, 7, 9, and 10, the concentrate was prepared by adding the fluorozirconic acid to the reaction product with stirring, and then adding a portion of deionized water to clarify the viscosity of the mixture. Then the nitric acid was added, followed by a second portion of deionized water. The total amount of deionized water used was enough to increase the final volume of the concentrate to 200 ml in example 3 and 250 ml in examples 5, 7, 9 and 10. A post-rinsing composition without chromium was made by diluting the concentrate prepared previously to a mixture of 1% volume / volume with tap water. In example 4, the concentrate was prepared by adding EL DOWANOL PM to the reaction product with stirring. The fluorozirconic acid was then added, followed by a portion of deionized water to clarify the viscosity of the mixture.

Finally the nitric acid was added, followed by a second portion of deionized water. The total amount of deionized water used was enough to increase the final volume of the concentrate to 150 ml. A post-rinse composition without chromium was made by diluting the concentrate prepared above to a mixture of 0.6% volume / volume with tap water. In Example 6, the concentrate was prepared by adding the Dowanol DPM to the reaction product with stirring. Then the fluorozirconic acid was added. Finally, enough deionized water was added to increase the final volume of the concentrate to 250 ml. A chromium-free post-rinse composition was made by diluting the above-prepared concentrate to a 0.5% volume / volume mixture with tap water. The pH was then adjusted to the final value of 4.32 using 10 ml of 1 molar sodium hydroxide. In Example 8, the concentrate was prepared by adding the fluorozirconic acid to the reaction product with stirring, and then adding the nitric acid. Next, a portion of deionized water was added to clarify the viscosity of the mixture. Finally Dowanol PM was added, followed by a second portion of deionized water. The total amount of deionized water used was enough to increase the final volume of the concentrate to 250 ml. A chromium free post-rinse composition was made by diluting the above prepared concentrate to a 1% volume / volume mixture with tap water. The pH was then adjusted to a final value using 15 ml of 1 molar sodium hydroxide.

TABLE II: PREPARATION OF RINSING CONCENTRATES AND RINSING SOLUTIONS At concentration to 45 percent. At 1, 5 molar. 1.0 molar sodium hydroxide. At concentration to 67 percent. At concentration to 60 percent, concent. = concentrated.

PREPARATION OF THE PANEL FOR THE CORROSION RESISTANCE TEST The resistance to corrosion produced by various post-rinse compositions is set forth in Table III. Corrosion resistance was measured according to ASTM B117, entitled "Standard test method of verification with salt spray (fog)". For each test, cold rolled steel test panels of 10.16 x 30.48 cm (4 x 12 inches) were treated with Chemfos® 51, a pretreatment composition available from the PPG Industries, Inc. market. This pretreatment composition simultaneously cleans the steel and deposits an iron phosphate conversion coating. The pretreatment composition was applied as an aqueous solution at three percent volume / volume. The Chemfos 51 was heated to 60-63 ° C, then applied by spraying for one minute. Triton® X-100 and Triton CF-32 nonionic surfactants, marketed by Union Carbide Corporation, were added to the pretreatment composition as needed to perform further cleaning of the steel.

After applying the pretreatment composition, the test panels were rinsed by spraying or immersion for 30 seconds with tap water maintained at room temperature. Next, the test panels were immersed for 30 seconds in a post-rinse composition maintained at room temperature. Finally, the test panels were rinsed with a spray of deionized water for about 5-10 seconds, then dried for about 5-7 minutes at 135 ° C. In cases where the post-rinse composition was deionized water, the second immersion step was omitted, and the final rinse with water lasted for approximately 30 seconds instead of approximately 5-10 seconds. After pre-treating the test panels, a coating composition was applied. FSVH55507, a high solids polyester coating composition marketed by PPG Industries, Inc., was reduced according to the manufacturer's instructions and applied by spraying with a film thickness of 0.020 to 0.030 mm (0.8 to 1, 2 thousandths of an inch). The painted test panels were scratched to the metal from corner to corner forming an "X". Typically, three test panels were prepared for each post-rinse composition; for some control materials, only one or two test panels were prepared. The test panels were evaluated after a week of exposure to salt fog. The post-rinsing compositions without chromium were checked in three groups, with a variety of comparative examples included in each test group. The panels taken from the salt spray test were rinsed in running tap water. The loose paint and corrosion products of a scratch line were scraped with a soft abrasive pad, and the panels were dried with a paper towel. The washed scratch line was then covered with filament tape # 780, and then the ribbon was pulled hard at right angles to the panel. Three 2.54 cm (1 inch) segments were measured from each end of said line of hatching. Within each segment of 2.54 cm (one inch), the total width of delamination was measured at its widest point to the nearest 32nd of an inch (0.79 mm). The measurements were then averaged, and half of said mean was then referred to as scoring. The results are given in units of X / 32 inch, a separate result referring to each test panel. A failure indicates a shift greater than 16/32 of an inch in the full length of the line.

TABLE III CORROSION RESISTANCE IN STEEL WITH SEVERAL COMPOSITIONS POST-FLUSH 1 A post-rinse composition with mixed hexavalent / -valent chromium, marketed by PPG Industries, Inc. The post-rinse was used at 208 to 277 ppm of hexavalent chromium and a pH of 4.0-4.5. 2 A zirconium post-rinse composition, marketed by PPG Industries, Inc. Post-rinse was used as a 0.75 volume / volume solution at a pH of 4.2-4.7, at room temperature . EXAMPLE 11 PREPARATION OF A CHROMIUM-FREE POST-RINSING COMPOSITION An aromatic epoxy functional material was reacted with diethanolamine in an equivalent ratio of 1: 2. The following materials were used: Diethanolamine and the first portion of DOWANOL PM were added to a three-liter round bottom flask equipped with a nitrogen spray line. The mixture was flushed with nitrogen for five minutes, then the spray line was removed and a stopper was placed in the flask. The reaction mixture was heated to 100 ° C, then the EPON 828 and the second portion of DOWANOL PM were added continuously in two hours. After fully adding the second charge, the reaction mixture was held for two additional hours at 100 ° C, then deionized water was added continuously in 30 minutes. The reaction mixture was then cooled and filtered to yield a reaction product at 50.97 weight percent solids. The milliequivalents of nitrogen were measured at 1,725. This reaction product was used to make a post-rinse concentrate without chromium as set out in the following table: Concentrate or mix thoroughly with a small portion of deionized water to reduce viscosity. The fluorozirconic acid was mixed with the reaction product with moderate agitation, followed by the addition of nitric acid. Then enough deionized water was added to raise the total volume to one liter. A chrome-free post-rinse was made by diluting the above prepared concentrate to a 1% volume / volume mixture with tap water. The pH of the was adjusted to 4.30 using 1 molar sodium hydroxide solution. EXAMPLE 12 PREPARATION OF A CHROMIUM-FREE POST-RINSING COMPOSITION First a reaction product of an aromatic epoxy functional material and diethanolamine was prepared in an identical manner to that of Example 11. This reaction product was used to make a chrome-free post-rinse concentrate. as it is exposed in the following table: The concentrate was prepared by mixing the reaction product with Surfynol®, and approximately 200 grams of deionized water was added with mixing together with moderate agitation. Fluorozirconic acid and nitric acid were added. Deionized water was added enough to raise the total weight of the concentrate to 1000 grams. A chromium free post-rinse composition was made by diluting the above prepared concentrate to a 1% volume / volume mixture with tap water. The pH of the solution was adjusted to 4.33 using 1 molar sodium hydroxide solution. PREPARATION OF THE PANEL FOR THE CORROSION RESISTANCE TEST The corrosion resistance produced by the post-rinse compositions of Examples 11 and 12 was measured according to ASTM B117, entitled "Standard test method for verification with salt spray (mist). "in a manner similar to the corrosion resistance test for the post-rinse compositions of Table II. There were several exceptions to the panel preparation procedure indicated above for checking. With respect to the verification set "A", set forth in Table IV, aluminum panels 6061-T6 and hot-dip galvanized panels of 10.16 x 30.48 cm (4 x 12 inches) were also processed.

Another exception referred to the verification set "B", shown in Table V, where, in addition to the cold-rolled steel, electrogalvanized, ganvaneal and electro-zinc / iron panels measuring 10.16 x 30.48 cm ( 4 x 12 inches). The panels were cleaned in a Chemkleen intermediate alkaline cleaner 163 that can be obtained from PPG Industries Inc., as a ChemFil product. After rinsing, the panels were treated in Chemfos® 158, an iron phosphate pretreatment composition marketed by PPG Industries, Inc. The pretreatment was sprayed on the panels at 66 ° C for one minute at a total acid value of 9, 6 points and a pH of 5.4. The panels were rinsed in room tap water and then post-rinsed and painted as in the previous panel assemblies. Verification set B also included zinc phosphate panels; a panel of each substrate for each post-rinse composition. These panels were cleaned in a standard intermediate alkaline cleaner, and rinsed in a conditioning rinse. The panels were phosphatized by immersion using Chemfos® 700, a zinc phosphate pretreatment composition marketed by PPG Industries, Inc. The treatment time was two minutes and the temperature was about 52 ° C. The zinc phosphate was followed by an ambient rinse, post-rinse and paint as in the previous panel assemblies.

TABLE IV ASSEMBLY OF VERIFICATION TO Good corrosion resistance shown in cold rolled steel and hot dip galvanized steel can be achieved without sacrificing corrosion resistance on aluminum substrates where multiple types of substrates are rinsed with the rinse composition of the present invention.

TABLE V TEST ASSEMBLY B Good corrosion resistance is achieved for these different substrates as they represent the lower values in Table V for the rinse solution of example 12.

Claims (19)

1. CLAIMS 1. A chrome-free post-rinse aqueous passive composition for treating phosphate metal substrates including:
2. A. The reaction product of an epoxy functional material containing at least two epoxy groups; and an alkanolamine, or a mixture of alkanolamines; Y
3. B. A material selected from the group consisting of Group IV-B metal ion, or a mixture of Group IV-B metal ions. The composition of claim 1, wherein the metal ion of Group IV-B is titanium present in an amount of 35 ppm to about 125 ppm. The composition of claim 1, wherein the reaction product is present at a level of at least 100 ppm, based on the level in the weight of solids of the reaction product on the total weight of the post-rinse composition without chromium.
4. 4. The composition of claim 1, wherein the reaction product is present at a level of about 400 ppm to about 1400 ppm, based on the level of the solids weight of the reaction product on the total weight of the composition post. -Rinse without chromium.
5. The composition of claim 1, wherein the epoxy functional material contains aromatic groups.
6. 6. The composition of claim 5, wherein the epoxy functional material is the diglycidyl ether of a polyhydric phenol.
7. The composition of claim 1, wherein the reaction product is prepared using a primary or secondary alkanolamine, or mixtures thereof.
8. The composition of claim 7, wherein the reaction product is prepared using diethanolamine.
9. 9. The composition of claim 1, wherein the Group IVB metal ion is zirconium ions which are present at a level of up to about 2000 ppm. The composition of claim 9, wherein the zirconium ions are present at a level of approximately

   75 ppm to about 225 ppm. The composition of claim 9, wherein the zirconium ions are added as a solution of fluorozirconic acid. The composition of claim 1, wherein the pH of the chromium-free post-rinse composition is from about 3.5 to about 5.5. The composition of claim 1, wherein the pH of the chromium-free post-rinse composition is from about 4.0 to about 4.7. 14. A chrome-free post-rinse concentrate to be diluted with water to treat phosphate-coated metal substrates including:

   A. The reaction product of: An epoxy-functional material containing at least two epoxy groups; and An alkanolamine, or a mixture of alkanolamines; Y

   B. A material selected from the group consisting of Group IV-B metal ion, or a mixture of Group IV-B metal ions. 15. A process for treating a phosphatized metal substrate that includes contacting said phosphatized metal substrate with the chromium-free post-rinse composition of claim 1. 16. The method of claim 15, wherein the chromium-free post-rinse composition is applies at a temperature of about 5 ° C to about 100 ° C. The method of claim 15, wherein the chromium-free post-rinse composition is applied at a temperature of about 20 ° C to about 60 ° C. The method of claim 15, wherein the phosphate conversion coating used to prepare the phosphatized metal substrate is an iron phosphate conversion coating. 19. The coated article prepared by the method of claim 15.