CA1046872A - Metal surface treating aqueous polymer zirconium composition and process - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The corrosion resistance and siccative finish bonding characteristics of a metal surface are improved by contacting the surface with an aqueous composition consisting of a soluble zirconium compound and a polymeric material. The aqueous composition can be applied to a surface having a conversion coating deposited thereon, to improve the qualities of the coating.

Description

104~872 BACKGROUND OF THE INVENTION
In the art of treating metal surfaces, it is common practice to improve the corrosion resistance characteristics and paint bonding qualities of a metal surface by depositing a conversion coating or the like thereon. In order to improve the qualities of the already applied protective coating or conversion coating, it is common practice to subsequently treat the metal surface after the conversion coating has been formed thereon. To enhance the corrosion resistance of an unpainted metal surface, or to prepare a metal surface for the reception of a final finish or siccative coating, such as a paint, enamel~ or sanitary lacquer, various coating methods and compositions have been employed. For example, compositions consisting essentially of aqueous acid phosphate or acid chromate solutions have been employed to treat bare metal surfaces already possessing a conversion coating to improve the :

corrosion resistance and paint bonding characteristics.
Chromate treatments employed to deposit a coating on a metal surface or as a treatment after a conversion coating has been formed thereon are disclosed, for example in United States -Patent Nos. 2,825,697; 2,678,291; 2,936,254 and 2,928,763. ~-An important shortcoming, which treatments of the kind to which reference has been made possess, is the inherent tox-icity and presence of noxious~materials in the effluents, such as hexavalent chromium, phosphates, and fluorides. Waste dis-posal problems, handling problems, and difficulties due to thecorrosive action of the composition on ~he equipment employ-ed are created by the presence of acidic components in the bath effluent.
Another problem encountered with chromium containing treatments is that certain paint or lac~uer systems will chip, peel, or blister when applied to a metal surface which has been treated with chromates. Workpieces having complex configura-tions will accumulate residues of chromium salts in areas such as crevices, pockets and joints. These areas will tend to dis-play blistering, peeling, and generally inferior siccativefinish adhesion.
Resinous materials have been incorporated in a chromate treating solution, so as to provide on the metal surface a final finish or an excellent base for subse~uent painting.
Solutions and dispersions of this kind are disclosed, for exam-ple, in United States Patent Nos. 2,902,3gO; 3,053,692;
3,132,055; 3,185,596; 3,189,488 and 3,189,489. However, these treating solutions and the protective coatings formed therefrom have not eliminated the detrimental effect of the high toxicity ,~
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~3~6872 associated with hexavalent chromium.
The primary object of the present invention is to provide a method for the treatment of metal surfaces which will enchance the corrosion resistance and siccative finish bonding characteristics of the surface.
An added object of this invention is to provide a process and treating composition for metal surfaces which enhance the adhesion properties of a subsequently applied siccative finish while eliminating the waste efflu-ent disposal problems encountered with compositions employed heretofore.
A concomitant object of this invention is to provide an improved method for treating metal surfaces on which a conversion coating has already been deposited.
DETAILED DESCRIPTION OF THE INVENTION
I have discovered a chrome-free process and composition for treating the surfaces of metals such as iron, steel, zinc, aluminum and alloys in which they are the predominant constituent. The aqueous composition em-ployed in the present process consists essentially of a soluble zirconium compound and a polymeric material. When the composition is applied to metal substrate, a coating is obtained which enhances corrosion resistance and siccative finish bonding.
Thus this invention seeks to provide a process for treating a metallic surface to improve the corrosion resistance and the siccative finish bonding characteristics of said surface which comprises contacting said sur-face with an aqueous composition consisting essentially of a soluble zirconium compound in an amount of from about 0.1 grams/liter to about 3.5 grams/liter, measured as ZrO2, and a polymeric material in an amount of from about 0.1 grams/liter to about 5.0 grams/liter.
It should be understood that the term "aqueous composition" or "aqueous solution" utilized herein means the aqueous admixture comprising zirconium, present as a soluble zirconium compound, and a polymeric material.
The concentration of zirconium present in the aqueous composition is expressed herein as the concentration of ZrO2. This means that the zirconium, present as a soluble zirconium compound in solution, is in the ~ .
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1046~372 form of tetravalent zirconium whose concentration is expressed as the concentration of its oxide. Although the resinous or polymeric material may be present in the aqueous composition either in dissolved form, emulsion form, or in the form of in-soluble particles dispersed in the composition, the term "aqueous solution" when employed herein is to be understood as including an emulsion or dispersion of the polymer and zir-conium compound, as well as a solution of the polymer and zir-conium compound. Examples of water soluble polymeric or resin-10 ous materials that can be utilized are polyacrylic acid, poly-vinyl alcohol, hydroxyethyl ethers of cellulose, ethylene maleic anhydride, polyvinyl pyrollidine, and polyvinyl methyl ether.
An example of a polymeric material in the form of dispersed particles that can be utilized is an acrylic copolymer latice. -Of course, the dispersed polymer or late~ should be stable, in the presence of the other ingredients comprising the aqueous composition.
A wide variety of soluble zirconium compounds can be employed. The selection of the compound to be employed will 20 depend on its commercial availability and its stability in solution with the polymeric material. It is, of course, necessary that upon its inclusion in the aqueous solution, it should not hydrolize to insoluble hydrous zirconium dioxide or an insoluble zirconium salt at the operating p~ and temperature of the process, nor should it cause coagulation of the polymeric material.
Typical examples of zirconium compounds which can be employed in the aqueous composition are alkali metal and ammon-ium fluozirconate and ammonium zirconium carbonate. The a~ueous composition should comprise at least 0.1 grams/liter of the zirconium compound (measured as ZrO2). In the preferred em-bodiment, ammonium zirconium carbonate will be employed in the aqueous composition and its concentration, measured as ZrO2 will preferably be from about 0.1 grams/liter to about 3.5 grams/
liter.
As has been suggested hereinabove, the resinous or polymeric material may include both water soluble as well as water dispersible polymers. In the preferred embodiment of 10 this invention, the aqueous composition comprises a water sol- `
uble polyacrylic acid. Water dispersible emulsions or latexes of polyacrylic acid derivatives are also commerically available, -;
such as the alkali metal and ammonium salts of polyacrylic acid, ~-and the polyacrylic acid esters. By the term"acrylic acid polymer" or "polyacrylic acid", it should be understood that this means and applies to all types o polymers to be utilized in the aqueous composition, whether they be water dispersible or water soluble salts, esters, or the acid. Aqueous solutions of polyacrylic acid are available commercially, for example, those sold under the name Acryso~ A-l, Acrysol*A-3, and Acrysol*A-5. Water dispersible emulsions of polyacrylic acid esters are also available, for example those sold under the name Rhoplex*Ac-35.
The amount of polymer utilized can vary over a wide range. It is preferred that the polymeric material in the aqueous composition be present in an amount from about 0.1 grams/liter to about ~.0 grams/liter. Naturally, the amount of - -polymeric material present in the solution must be sufficient to aid in the forming of a film on the metal surface. A
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surprising aspect of the present invention is that an a~ueous composition having a concentration of polymeric material within the preferred range indicated above gives satisfactory uniform coatings which adhere to the surface and improve the siccative finishing bonding characteristics of the surface. It is ap-parent that the amount of polymer present should be that amount which will be particularly effective under the particular operat-ing conditions of the treating process, so as to improve the corrosion resistant capabilities and siccative finish bonding properties of the already formed coating, or in the case where no coating has been deposited, to improve the corrosion resis-tance of the bare metal surface and its paint bonding charac-teristics. It has been found that the amount of polymeric ma-terial should preferably range from about 1.0 part to about 2.0 parts by weight for each part by weight of zirconium in the aqueous composition.
~ t should be noted that the combination of a zirconium compound and polymeric material is more effective, in terms of corrosion resistance and paint bonding characteristics, than the individual constituents when applied to a metal surface.
This effect will be evident from the examples included herein-below.
As already set forth herein, any polymeric material which is stable in the presence of the zirconium compound in a water-based composition can be used in the practice of this invention. The aqueous compositions to be used preferably~are prepared by addition of the components to water. This negates any problems with respect to stability for prolonged periods of time should an aqueous concentrate be prepared and then r ~ --6--~ 04687Z
added directly to water in order to prepare the aqueous composi-tion for use. It has been observed that, u~der certain condi-tions, should an aqueous concentrate be prepared to make up the aqueous composition, hydrolysis and salting out of both the zirconium compound and the polym~r is evident.~ of course, to prepare the composition each constituent is preferably added -~
to the appropriate amount of water to prepare a working bath having constituent concentrations within the operative ranges set forth herein.
preferably, the zirconium compound and polymer will evidence stability by remaining uniformly distributed through-out the aqueous phase of the composition, although in certain cases stirring of the composition may be employed to maintain a uniform dispersion during operation. In the preferred embodi-ment of the invention, the polymeric material should already be in solution or dispersed in the aqueous phase prior to the addition of the zirconium compound. This will further insure against any hydrolysis and precipitation of zirconium in the prepared aqueous bath.
It has been observed that should the concentration of polymeric material be less than 0.1 grams/liter no substantial improvement in the siccative finish bonding properties will result. In the preferred embodiment of this invention, with respect to the upper concentation limit of polyacrylic acid, it has been found that no additional improvement over those obtain-ed initially is experienced by the use of more than about 5.0 grams/liter of the polyacrylic acid. The polymeric material by itself has little or no value, but combination of the polymer and the zirconium compound, as described herein, gives excellent and .
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1~4~;872 unexpected corrosion resistance and siccative finish bonding characteristics.
prior to treatment with the aqueous composition, the metal surface can be treated with a solution which reacts with the surface to form a conversion coating. The conversion coat-ing will have been applied using commonly employed processes and techniques known to the art. Particularly, the conversion coatings employed are those referred to as chromate`coatings or phosphate coatings. By chromate coatings, we mean those pro- -duced from aqueous baths containing hexavalent chromium, tri-valent chromium, and/or salts thereof, as well as additional constituents such as phosphoric acid, and fluoride. By phosphate coatings, we mean those produced from aqueous solutions contain-ing phosphoric acid and salts thereof, as well as additional constituents such as fluorides, molybdates, chlorates, nitrates, and various organic accelerators.
Formula 1 is an example of a suitable dry chromate coating composition which can be added to water to form a chromate coating solution which can be employed to treat metal surfaces prior to their treatment with the aqueous composition:

Formula 1 % by Weight Chromic Acid 33_37 Potassium Fluozirconate 15-16 Sodium Bifluoride 45-49 Formula 2 is an example of a suitable concentrated chromate-phosphate coating solution which can be diluted to desired strength with an aqueous hydrofluoric acid solution and can beemployed to treat a~uminum surfaces forming a chromate-phosphate coating thereon, prior to the treatment with theaqueous composition.

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Formula 2 % by Weight Chromic Acid 57-60 Phosphoric Acid (75%) 15-16 Water 24-26 Formula 3 is an example of a suitable concentrated phosphate coating solution which can be diluted to desired strength and can be employed to treat metal surfaces prior to contact with the aqueous composition.

Formula 3 - -O/D by Weight Phosphoric Acid (75%) 2-4 Ammonium Hydroxide (26Be) 1-2 Ammonium Bifluoride .1-.8 Ammonium Molybdate .1-.3 Water 93-96 A surprising aspect of the present invention has been `~
observed when the aqueous composition is employed subsequent to treatment with a coating solution as described in Formula 3 hereinabove. A coating deposited by employing the coating solu-tion prepared with Formula 3 on aluminum surfaces has the tend-ency to discolor, for instance after exposure to boiling water.
Should coatings of this type be applied to aluminum containers and then subjected to the conditions of pasteurization or pasteurization procedures, such as immersion in boiling water at 250F and 15 psi, undesirable discoloration will result~
When the aqueous composition of the present invention is applied to aluminum surfaces having an underlying phosphate con-version coating of the kind formed from a solution of Formula 3, this discoloration can be prevented upon exposure of the sur-face to the temperature and pressure conditions described above.

~: _9_ ~046872 Of course, the compositions of the present invention can be applied to a bare metal surface having no prior coating thereon. A surprising result is that the surface will maintain its original appearance and a coating will be produced which will also improve the adherence of a subsequently applied siccative finish or sanitary lacquer,such asan acrylic based coat, and the surface will portray improved corrosion resistance.
A coating produced in the manner described herein is extremely useful per se, since it does add corrosion resistant properties to the metal surface. Should a siccative finish be applied to the treated surface, unexpected improved adhesion of the applied siccative finish is obtained.
During the coating operation, depletion of the consti-tuents in the aqueous composition will occur at about the same rate. These losses must be replaced to maintain the bath within its optimum operating limits. The coating bath is maintained within its prescribed limits with suitable additions of the constituents in the same proportions in which these constituents exist in the operating aqueous composition.
The preparation of the polymers suitable for use herein is well known to the art. The acrylic acid polymer resins to be employed in the preferred compositions of the present in-vention are prepared by means which can be considered solution-type polymerization processes which result in a low molecular weight polymer. ~owever, resins made by dispersion, bulk and suspension type polymerization processes can also be used.
One skilled in the art will be in a position to choose the particular polymeric material to meet specific conditions and circumstances under which the composition is to be employed.

-` 1046872 In the process of the present invention the metal substrate is brought into contact with the aqueous composition under suitable con-ditions of pH, temperature, and contact time.
The process is employed after cleaning of the metal surface has been accomplished. The cleaning step can be carried out by conventional methods which form no part of the present invention. A conventional acid or alkaline cleaner can be employed followed by a water rinse.
Should the surface be heavily soiled, a detergent cleaner additive may be employed in the cleaning step.
The time of treatment of the metal surface with the aqueous composition need only be long enough to insure complete wetting of the surface and can be as long as 30 minutesO Preferably, contact time be- -tween metal substrate and solution should be from about one second to about one minute. One of the distinct advantages of the present invention is that suitable protection is obtained on the metal surface utilizing a treating time of as little as one second~
The coating process can be effected by employing any of the contacting techniques known to the art. Contact can be effected by spray, immersion, or flow coating techniquesO Preferably the aqueous composition will be applied to the metal by conventional spray methods.
The pH of the composition can vary over a wide range and is influenced by the ingredients comprising the composition, particularly the soluble zirconium compound usedO It has been found that best results are obtained when the operating pH of the composition is from about 6~0 to about 8Ø
The process can be operated at a temperature from about 60FD
to about 120F. It is preferred to operate the process at a temperature of from about 70Fo to about 100F~ Generally, a slight change in the temperature will not ~ 11 -~' -` 1046872 necessitaee substantial alteration of the treating time, concentration parameters, or pH adjustment.
Following application of the aqueous composition, the surface can be subjected to a drying operation. The preferred range of temperaturesfor the drying operation is from about 60F to about 500F and, of course, the length of the drying step will depend upon the temperature utilized.
Once the drying step has been effected, a siccative finish, such as a lacquer, can be applied to the surface with 10 considerable adhesion improvement. After the drying step and application of a siccative finish, the workpiece is ready for use and is highly resistant to corrosive attack, such as from any liquid or foodstuff placed in a formed metallic container formed from the workpiece. A particular advantage of the pre-sent invention is that after contact with the aqueous composi-tion has been accomplished, the workpiece is resistant to c~rrosive attack, even when subjected to prolonged exposure to air due to processing line stoppage prior to application of the siccative finish.
The following examples are illustrative of this inven-tion and are not considered as limiting for other materials or operating conditions falling within the scope of the invention that might be substituted. Example 1 is set forth ~or the purpose of illustrating the preparation of an aqueous composi-tion within the purview of this invention. Examples 2 through 12 illustrate the improved results obtained employing the aqueous composition.
In the examples, certain comparative tests, defined hereinbelow, were effected on representative test specimens.

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-- ~0468~2 Reverse impact tests were performed to determine the adhesive characteristics of an organic or siccative coating applied to the surface. This test is commonly employed in the testing of paints. In the reverse impact test, after the panels are coated with an appropriate paint, the test surface is position-ed with the painted side down and the unpainted surface is impacted by a falling 1/2" ball with a force measured at 24 inch-pounds, thereby deforming the test surface. The impacted area is then subjected to a tape adhesion test wherein tape is applied firmly to the impacted surface and the tape is allowed to sit for a specified length of time, usually about one minute. The tape is then drawn back against itself by a rapid pulling motion in a manner such that the tape is pulled from the surface at the impacted area. The reverse impact test can also be effected after the surface has undergone an immersion test as described below.
Selected test specimens were subjected to an Immersion Test. In this procedure, the test specimens are immersed in deionizing water or in a solution consisting of deionized water and 1% by volume of a li~uid detergent at 180F for 30 minutes. The specimens are then removed from the solution and rinsed, then blotted dry. A portion of the test specimen is immediately scribed with a cross-hatch tool having eleven cutting blades spaced one millimeter apart. Using the cross-hatch tool, one hundred s~uares measuring one millimeter by one millimeter are scribed on the painted surface. This is accomplised by drawing the scribing de~ice across the area to be tested and then repeating the procedure by drawing the device across the same area but at a 90~ angle to the first --` 104~i872 scribing. The cross-hatched area is subjected to a tape ad-hesion test wherein tape is applied firmly to the surface of the test panel over the entire cross-hatched area so that no air bubbles or wrinkles are present between the tape and the surface. The tape is allowed to set for one minute and is then drawn back against itself with a rapid pulling motion in a mmaner such that the tape is pulled from the surface of the specimen.
A specific area on the test specimens which had not been impacted or cross-hatched was also subjected to a Tape Adhesion Test. In this test, tape is applied firmly to a portion of the surface which has not been impacted or cross-hatched. The tape is applied in a manner such that no air bub-bles or wrinkles are present between the tape and the surface.
The tape is allowed to set for one minute and then drawn back against itself with a rapid pulling motion in a manner such that the tape is pulled from the surface of the specimen. This tape adhesion test is referred to herein as a "Field Test".
After each test, the test specimens were evaluated and rated, employing the rating system set forth hereinbelow.
The specimens were evaluated for paint loss or paint failure utilizing a rating scale of 0 to 10 wherein 0 represents complete paint loss and 10 represents no paint loss. This quantitative determination was performed on the impacted area, the cross-hatched area and the "field test" area of the test specimens.
EXAMP~E 1 30 mls. of an acrylic acid polymer (Acrysol*A-l, an aqueous solution comprising polyacrylic acid, manufactured by Rohm and ~aas) were added to 3 liters of water. ~0 mls. of * Trademark ' ~ -14-` ` 1~4~872 commercially available ammonium zirconium carbonate (an aqueous solution having a pH of about 8.5 marketed by TAM, division of National Lead Industries, Inc., and having 9% by weight of zirconium therein (measured as ZrO2) were then added such that an aqueous composition comprising ammonium zirconyl carbonate and polyacrylic acid having about 2 grams/liter of zirconium (measured as ZrO2) was formed. The pH of the solution was measured at 7.2.

3 l/2 " wide aluminum coil stock was employed in this ~ -procedure. The aluminum coil was put into 6" long test panels.
The panels were cleaned with an alkalin~ cleaner at 160~F for 15 minutes and rinsed with water. The test panels were then subiected to a conventional deoxidizing process and then sub-jected to a chromate-phosphate processing sequence providing a chromate-phosphate conversion coating on the surface. A
coating solution was prepared specified in Formula 2 hereinabove was applied to the surface, depositing a chromate-phosphate coating of 5-7 mg. per square foot.
One set of control panels were cleaned and deoxidized and another set of control panels was cleaned, deoxidized, and contacted with the above chromate-phosphate solution.
Coated test panels were immersed in an aqueous com-position consisting of polyacrylic acid and ammonium zirconium car~onate having a polyacrylic acid concentration of 2.7 grams/
liter and a zirconium concentration of 1.8 grams/litèr, for 15 seconds at room temperature, and allowed to air dry. The pH
of the aqueous composition was recorded at about 7.2.
All test panels, i.e. those treated with the ammonium r C~ 15 ' 1046872 zirconium carbonate and polyacrylic acid composition, as well as the control panels, were then subjected to various testing procedures set forth below in order to determine the effects on the workpiece.
A "room temperature weight loss" test ~d "high tempera-ture pressure weight loss" test were performed on the control and test panels. In the high temperature-pressure test, the specimens were placed in a pressure vessel having a glass -liner therein and a carbonated beverage was poured therein.
The vessels were sealed and kept at 180~F for 5 hours in one sequence and 24 hours in a second sequence. The control and test specimens had been weighed prior to the test and were - -weighed thereafter. The average wei&~t losses in milligrams per square foot of the panels is noted in Table 1 below, based on the observed weight loss of the groups of panels in -each treatment sequence.
In the Room Temperature weight loss test, the control and test panels, after weighing, were placed in the vessels at room temperature and the beverage poured therein. Specific groups of specimens were permitted to sit therein for 1, 2, 3, 4, 5, and 7 days, respectively. At the conclusion of the test period, the panels were thoroughly rinsed, dried and re-weighed.
Appreciable differences in weight change were noted. The results are listed in Table I hereinbelow.

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It will be appreciated from the results in Table 1 that the test panels immersed in the aqueous composition gave sup-erior and unexpected protection over the Controls in terms of weight loss, when all test specimens were exposed to the corro-sive effect of the beverage.

3" wide aluminum can stock specimens were employed in this procedure. The specimens were cut into 6" long panels and cleaned in an acid cleaner at 170F for one minute.
Four sets of control panels were immersed in four dif-ferent baths comprising zirconium acetate, the baths having zirconium concentrations of 0.5 grams/liter; 1.0 gram~liter; 1.5 grams/liter; and 2.0 grams/liter respectively (measured as zrO2).
Four sets of control panels were immersed in various ammonium ~irconium carbonate solutions having concentrations of zirconium of 0.5 grams/liter; 1.0 gram/liter; 1.5 grams/liter and 2.0 grams/liter respectively (measured as ZrO2).
Test panels were treated with an aqueous composition comprising ammonium zirconium carbonate and polyacrylic acid.
Four sets of test specimens were utilized in four aqueous compositions having zirconium concentrations of 0.5 grams/
liter; 1.0 gram/liter; 1.5 grams/liter and 2.0 grams/liter and polyacrylic acid concentrations of 0.7 grams/liter; 1.4 grams/
liter; 2.1 grams/liter; and 2.8 grams/liter respectively.
A11 test specimens were then painted with an acrylic white paint and then were subjected to the detergent immersion test procedure. The panels were then subjected to reverse-im-pact, cross-hatch, and "field" tests, and the results are listed in Table 2 below.

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t '(~ - 20-It will be observed that the ammonium zirconyl carbon-ate and polyacrylic acid composition gave outstanding results in the test as compared to the control specimens.

Aluminum can stock was employed in this procedure. 3 inch X 6 inch panels were prepared from the can stock. The specimens namely 4 sets of control panels were treated in the zirconium acetate solutions as in Example 3, 4 sets of control panels were treated with the ammonium zirconyl carbonate solu-tions as in Example 3, and 4 sets of test panels were immersedin aqueous compositions comprising ammonium zirconyl carbonate and polyacrylic acid therein and having the respective zircon-ium concentrations of 0.5 grams/liter; 1.0 gram/liter and

2.0 grams/liter (measured as ZrO2) and polyacrylic acid concen-tration of 0.7 grams/liter; 1.4 grams/liter; 2.1 grams/liter and 2.8 grams/liter respectively. A vinyl interior lacquer was applied to all panels and they were then subjected to a detergent immersion procedure and then reverse-impact, cross-hatch, and "field" testing. The results of the tests are list-ed in Table 3 below.

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Groups of aluminum test specimens were employed in this procedure. The cleaned test specimens comprised 3" X 6"
panels. The panels were treated with a zirconium acetate solu-tion, an ammonium zirconium carbonate solution, and an aqueous composition comprising ammonium zirconium carbonate and poly-acrylic acid having the concentration parameters indicated in Table 4 below. The test panels were painted with an acrylic whitepaintandw~ethen subjected to a deionized water immersion test at 180F for 1/2 hour. They were then subjected to reverse-impact, cross-hatch, and "field" testing. The results are list-ed in Table 4 below.

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3" X 6" aluminum can stock panels were used in this procedure. The specimens were cleaned with an alkaline cleaner at 160F for fifteen minutes. They were then rinsed and deoxidized and then subjected to a phosphate processing sequence providing a phosphate conversion coating on the surface. The phosphate coating solution of Formula 3 was applied to the test specimens.
Control panels were then painted with a white 10 acrylic paint. The control panels were then subjected to an immersion soak test with 1% detergent solution and then sub-jected to reverse-impact, cross-hatch, and field testing.
The results are listed in Table 5 below. ~
After deposition of the phosphate coatings, two --sets of test panels were treated with two separate aqueous compositions comprising ammonium zirconium carbonate and polyacrylic acid having a zirconium concentration of 1.0 grams/liter and 2.0 grams/liter respectively and a polyacrylic acid concentration of 1.4 grams/liter and 2.8 grams/liter 20 respectively. The test panels were then painted with the white acrylic paint. The test panels were then subjected to the water-soak immersion test with detergent and then sub3ected to reverse-impact, cross-hatch, and field testing. The results are listed in Table 5 below.

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In this procedure aluminum test panels 3" X 6" ~
were employed. The panels were cleaned in acid cleaner at 180F for one minute. The panels were then subjected to spray treatment with the following compositions: a) poly-acrylic acid; b) ammonium zirconium carbonate;c) ammonium fluozirconate; d) aqueous composition comprising polyacrylic acid and ammonium zirconium carbonate; and e) an aqueous ~composition compris~ polyacrylic acid and ammonium fluozir-conate. The panels were then dried at ambient temperature.
The concentrations of the particular constituents in the respective treating compositions are listed in Table 8 below.
The panels were then treated with an acrylic exterior paint. An additional set of control panels was cleaned and then painted.
Thereafter, the control and test panels were subjected to an immersion test with detergent at 180F for 30 minutes. All panels were then subjected to reverse-impact, cross-hatch, and field testing and the results are listed in Table 6 below.

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u~ ~ n oo o oo oo o h ~d ~ oo o o o ~n ~ ~
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t~
n~ Lr~o o o o oo o o~ O
oo oa- ~t ~: ~ ~

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,.
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~--I o ~ ~ h o ~ h ¢ ~ o h--I h ¢ --~ h--o~ h rJ h ~ h o 8 ~ ~ ~ o o ~ , ~ ¢ ~o.~ ~o o C

~.

~6872 3 inch X 4 inch aluminum test panels were employ-ed in this procedure. The panels were cleaned with an alkaline cleaner at 180F for one minute. They were rinsed with water and groups of the test panels were subJected to various phos-phate processing sequences providing phosphate conversion coat-ings on their surfaces. The phosphate coating solutions employ-ed on the groups of test panels were as follows:

75%
Phosphoric Ammonium Sodium Test Acid Bifluoride Molybdate Runs g/l g/l g/l a 9.8 1.14 0.1 b 1.2 0.29 0.1 c 3.5 0.57 0.1 d 7.0 0,86 0.1 -e 1.2 0.29 0.1 f 3.5 0.29 0.1 -~

After each group of test panels were coated with the particular phosphate conversion coating solutions specified above, test panels from each group were contacted with an aqueous composition comprising ammonium zirconium carbonate and polyacrylic acid having a zirconium concentration of 1.8 grams/liter (measured ZrO2) and a polyacrylic acid concentration of 2.73 grams/liter. A second set from each group of coated panels was treated with a deionized water rinse following the coating sequence with no further treatment thereafter. Each set of panels was then painted with an acrylic exterior white paint.

~r~
~ ~ -31-`` -` ` lQ46872 The painted pa~els were then subjected to the following tests: `
a) Immersion in water at 150~F for 30 minutes -and then subjected to the cross-hatch test. -~
b) Immersion in a 1% detergent solution at ~' 180~F for 30 minutes and then subjected to ;,"S!.' the cross-hatch test.
;
,.~ . . :
;' ~ The table below lists the results of the tests.
.:
The specimens were qualitatively evaluated for paint loss.
The ratings appearing in Table 7 below are as follows: (+) representing no paint loss, (0) representing slight or moderate .," .
paint loss, and (-) representing heavy or total paint loss.
~i ~ .
Table 7 Zirconium ~;~' + .
Polyacrylic Acid Deionized Water Test Water 1% Detergent Water 1% Detergent ~ Runs Immersion Immersion Immersion Immersion i`l a + 0 ~,20 b + + + ~
;. . c + +
d + + +
, e + + + 0 ;~
~ f +
,. .
~ .
~1, ~ EXAMPLE 9 -, 2" X 4" tin plated steel panels were used in this procedure. The specimens were cleaned with an alkaline cleaner o ,`~ ` at 17~`F for one minute and rinsed. Control panels were cleaned with the alkaline cleaner, rinsed and dried. Control panels ; were painted with a whi~e acrylic paint. Two sets o~ test .

panels were treated with two separate a~ueous compositions `` 113 46~72 comprising ammonium zirconium carbonate and polyacrylic acid having a zirconium concentration of 0.5 gram/liter and 1.5 grams/liter respectively and a polyacrylic acid concentration of 0.7 grams/liter and 2.1 grams/liter respectively. The test panels were driedfor one minute at 400F and then painted with white acrylic paint. Test panels, and Controls were then subjected to the water soak immersion test with detergent and then subjected to cross-hatch and field testing. The results are listed in Table 8 below.
Table 8 Treatment Cross Field ~-Hatch Test_ Controls 0 2 Ammonium Zirconyl Carbonate and Polyacrylic Acid ZrO~ Concentration Polyacrylic Acid Concentration 0.5 g/l 0.7 g/l 10 9 1.5 g/l 2.1 g/l 10 9 In this procedure aluminum test panels 3" X 6"
were employed. The panels were cleaned in an acid cleaner at 180F for one minute and rinsed. Cleaned and dried Gontr test panels were painted with a white acrylic paint.
Test panels were immersed in various aqueous compositions comprising ammonium zirconyl carbonate and various polymeric materials listed in Table 9 below for fifteen seconds at room temperature. The test panels were then dried at 400F
for one minute and painted with a white acrylic paint. The con-centrations of the par~icular constituents in the respective aqueous compositions listed in Table 9 were 2.0 grams/liter 1~6872 of ammonium zirconium carbonate and 2.0 grams/liter of the polymeric mater~al.
Thereafter the control and test panels were sub-jected to an immersion test in boiling ~ater for 30 minutes. All panels were subjected to reverse impact, cross hatch, and field testing and the results are listed in Table 9 below.

Table 9 Ammonium zirconium Carbonate +Reverse Cross Field ~~ Polymeric Materials Impact Hatch Test Controls Polyacrylic Acid, (Acrysol A-l, Rohm & Haas) 10 10 10 Polyacrylic Acid, (Acrysol A-3, Rohm & Haas) 10 10 10 Polyacrylic Acid, (Acrysol A-5, Rohm & Haas) 10 10 10 Polyacrylic Acid, (Goodrite*K37, Goodrich) 10 10 10 Polyacrylic Acid, (Goodrite*K702, Goodrich) 9 2 6 Carboxy vinyl polymer (Carbapol* ~ D
801, Goodrich) 10 10 10 Acrylic c~polymer dispersion, (Acrysol W~4, Rohm ~ Haas) 10 10 10 Ammonium polyacrylate, (Acrysol G110, Rohm & Haas) 4 10 10 Polyvinyl alcohol, (Lemol 5-88, Borden) 9.8 10 9 Acrylic emulsion (Rhoplex ~V-l, Rohm & Haas) 5 10 9 Acrylic hydrosol emulsion, (Elvacet*~012, Du Pont) 5 3 3 Additional test panels were immersed in aqueous compositions comprising ammonium zirconium carbonate and a * Trademark ~, -34-1~4687Z
polymeric material for 15 seconds at room temperature. The specimens were then dried at 400F for one minute and painted with a white acrylic paint. The concentration of ammonium zirconium carbonate in the aqueous compositions was 1.0 grams/
liter and the concentration of the polymeric material was 1.0 grams/liter. All panels were subjected to an immersion test in boiling water for 30 minutes and then subjected to the reverse impact, cross hatch, and field test and the results are listed in Table 10 below.

Table 10 Ammonium Zirconium Carbonate +Reverse Cross Field Polymeric Material Impact Hatch Test Control 0 0 0 Polyacrylic acid, (Acrysol A-l, Rohm ~ Haas) 10 10 10 Polyvinyl alcohol, (Lemol 5-88, Borden) 4 2 2 Polyacrylamide homopolymer, (P250, American Cyanamid) 10 10 8 Polyvinyl Methyl ether, (Gantrez M154, GAF) 3 10 12 Polyvinyl Pyrollidone, (NP-K30, GAF) 1 0 Phosphated Starch, (ARD 1230, American Maize) 9.9 10 10 ~ydroxy methyl cellulose, (WP-40, Union Carbide) 10 10 10 2'~ X 4" steel panels were used in this procedure.
The panels were cleaned with an alkaline cleaner at 170~F

for one min~te and rinsed. Control panels were dried and * Trademark painted with a white acrylic paint.
After cleaning and water rinsing, the test panels were treated with an aqueous composition comprising ammonium -zirconium carbonate and polyacrylic acid having a zirconium - -concentration of 1.0 gram/liter (measured as ZrO2) and a polyacrylic acid concentration of l.0 gram/liter. The panels were th~ndried on~ minute at 400F. The test panels were then painted with the white acrylic paint.
Test and control panels were subjected to the water --soak immersion test with 1.0% detergent solution and then sub~
jected to cross hatch and field testing. The results are ~ -listed in Table 11 below.

Table 11 Treatment Cross Hatch Field Test Ammonium Zirconium 9.0 9.5 Carbonate + Polyacrylic Acid Control - 0 0 EXAMPLE 12 `

2" X 4" galvanized steel panels were employed in this procedure. The specimens were cleaned with an alkaline cleaner at 170F for one minute and rinsed. Control panels were cleaned with an alkaline cleaner, rinsed and dried.
Control panels were painted with a white acrylic paint~

Test panels were treated with an aqueous composition comprising ammonium zirconium carbonate and polyacrylic acid -~
having a zirconium concentration of 1.0 gram/liter and a poly-acrylic acid concentration of 1.0 gram/liter. The panels were L~

then dried one minute at 400F and painted with the white - acrylic paint.
Test panels and controls were subjected to the water soak immersion test with 1% detergent solution and then subjected to cross hatch and field testing. The results are listed in Table 12 below.

Table 12 Treatment Cross Hatch Field Test Ammonium Zirconium Carbonate and Polyacrylic 10 10 Acid Control 2 4 . ~

Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for treating a metallic surface to improve the corrosion resistance and the siccative finish bonding characteristics of said surface which comprises contacting said surface with an aqueous composition consisting essentially of a soluble zirconium compound in an amount of from about 0.1 grams/liter to about 3.5 grams/liter, measured as ZrO2, and a polymeric mat-erial in an amount of from about 0.1 grams/liter to about 5.0 grams/liter.

2. A process as defined in claim 1 wherein the soluble zirconium compound is selected from the group consisting of ammonium zirconium carbonate, alkali metal fluozirconate and ammonium fluozirconate.

3. A process as defined in claim 1 wherein the polymeric material is selected from the group consisting of polyacrylic acid, esters and salts thereof.

4. A process as defined in claim 1 wherein the polymeric material is an acrylic acid polymer.

5. A process as defined in claim 4 wherein the polymeric material is polyacrylic acid.

6. A process as defined in claim 2 wherein the zirconium compound is ammonium zirconium carbonate.

7. A process as defined in claim 2 wherein the zirconium compound is ammonium fluozirconate.

8. A process as defined in claim l wherein the aqueous composition has a pH of from about 6.0 to about 8Ø

9. A process as defined in claim 1 conducted at a temperature of from about 60°F to about 120°F.

10. A process which comprises applying to a conversion coating, which has been deposited onto a metal surface, an aqueous composition as defined in claim 1.

11. A process as defined in claim 10 wherein an overlying siccative coating is applied after application of the aqueous composition to the conver-sion coating.

12. A process as defined in claim 11 wherein the conversion coating is a phosphate coating and the siccative coating is an organic finish coating.

13. A metallic surface having been treated with the composition defined in claim 1.

14. A metallic surface having a conversion coating and a coating of a composition as defined in claim 1, on said conversion coating.

15. A metallic surface having a conversion coating, an intermediate coating of a composition as defined in claim 1, and a siccative top coating.