MXPA97004518A - Composition with low sedimentation and process for the treatment of the aluminum and its alea - Google Patents

Abstract

The present invention relates to a conversion coating highly resistant to corrosion and strongly adherent to the paint that forms on the surface of aluminum-metal substrates when these surfaces are contacted for 0.5 to 60 seconds with a surface treatment bath with a base aqueous and sediment-free having a pH of .15 to 4.0 and containing a zirconium compound, phosphoric acid compound, oxidizing agent and a compound that is a source of hydrogen fluoride (in an amount that produces a concentration of HF from 0.00001 to 0.2 g / l in the treatment bath). This contact preferably is followed by a rinse with water and dry

Description

COMPOSITION WITH LOW SEDIMENTATION AND PROCESS FOR THE TREATMENT OF ALUMINUM AND ITS ALLOYS TECHNICAL FIELD This invention relates to a composition for a surface treatment and a process that forms a conversion coating on the surface of aluminiferous metals, which imparts excellent corrosion resistance and adhesion to the paint to these surfaces before the painting process. Aqueous solutions of this composition clear solutions that resist the production of a precipitating solid even when they contain aluminum? Id ?. The presumed ir.vcr.i ion so a li j with particularly good action for the surface treatment of stretched and pressed aluminum cans (hereinafter, it will generally be abbreviated as "aluminum EP cans"). Sediment adhesion in the equipment is inhibited and excellent corrosion resistance and adhesion to the paint is imparted to a substrate surface when the aluminum EP cans manufactured by the drawing and pressing of aluminum alloy sheets are submitted, before be painted and / or printed, to a Li uLuii ent? of supplying a bath for the surface treatment according to the present invention.

BACKGROUND OF THE INVENTION The outer bottom surface of EP aluminum cans are subjected to high temperature sterilization without being painted. If this region has a low resistance to corrosion, the aluminum oxidizes and blackens during this step, and consequently its appearance deteriorates. This phenomenon is generally known as "blackening" as a result, the conversion coating (de-inking) produced by the surface treatment should desirably have an intrinsically high corrosion resistance. So far, the surface treatment of EP aluminum cans is mainly carried out using phosphoric acid-chromate treatments containing Cr (VI) and zirconium-free chromate treatments. These treatments are applied to the surfaces of the cans as aqueous liquid compositions, which from now on will usually be called "bathrooms", for brevity, although these are usually applied by spraying the liquid "bath" on the cans more than by immersion of the cans in the bathrooms. A common example of chromate-free surface treatment baths is described in Patent Publication Japanese No. Sho 56-33468 [33,468 / 1981]. This surface treatment bath is an acid-based coating solution (pH 1.5 to 4.0) with an aqueous base containing phosphate, fluoride and zirconium or titanium or a mixture of these. The characteristics of this treatment bath without chromium, acid, are that it contains effective fluoride and does not contain a solid component that promotes precipitation. Since the chromium-free treatment bath does not contain toxic hexavalent chromium, it has been widely used in the present as a surface treatment agent for aluminum EP cans. However, this bath actually also suffers from significant disadvantages, as described in the following. When the surface treatment baths of the prior art are used in the can making lines, they are usually sprayed on the aluminum EP cans for about 15 to 30 seconds. When an object formed as aluminum cans EP is subjected to a spray treatment for a short period of time, the resulting coating may not be uniform, given the differences that occur between the different regions of the can, the flow rate of the bath and the contact conditions between the bath and the substrate surface. This creates variations or instabilities in anticorrosive performance. However, if the production of a large weight of the conversion coating on the external lower surface of the can is sought to stabilize the anti-corrosion performance, too much conversion coating will occur. icqionep in ol neck and saliont.es that develop after painting. This causes the problem of rolling the paint after the painting process. This variation in coating weight between the aforementioned regions is even more substantial in the case of aged surface treatment baths where the accumulated concentration of aluminum eluted in the solution has reached high values. When the surface treatment bath of the prior art is still mentioned in industry, the prevention of unacceptable paint lamination is a major disadvantage because the use of an effective concentration of fluoride is required, which must be maintained essentially at a constant value during the use of the bath, which is somewhat less than would be more desirable to prevent blackening and to avoid the formation of precipitates. Because of this, when the aluminum ions actually elute and enter the bath, or? uin'ii p; It is also possible to use the surface treatment bath described above, with its distinctive feature of not containing a precipitation-producing solid component. Even with this bath, then problems such as impurities in the equipment, clogging in the nozzles and the like actually occur.

Description of the invention Problems that are solved by means of the invention The present invention seeks to solve the problems already described for the prior art. In specific terms, the present invention presents a bath and a process that uses this bath and that is not only able to produce a conversion coating strongly adherent to the paint, highly resistant to corrosion, on the substrates surfaces of aluminum metals, It also has excellent properties in terms of uniformity in the conversion coating, inhibition of sedimentation and stability of the process.

SUMMARY OF THE INVENTION It has been found that: (i) a treatment bath can be obtained which maintains a transparent appearance when an oxidizing agent and a hydrogen fluoride generating compound which produces a particular HF concentration value is also present in a surface treatment bath containing a compound of phosphoric acid and a zirconium compound and has a pH of 1.5 to 4.0; (ii) excellent corrosion resistance and good paint adhesion can be imparted to the surface of aluminiferous metal substrates by forming a conversion coating thereon upon contacting the supertype of the? metaJes alum nlieros with the aforementioned conversion bath for 0.5 to 60 seconds; and (iii) the conversion coating formed by this means is very uniform, while at the same time an excellent inhibition of sedimentation is obtained.

The composition in which the sedimentation is largely inhibited, in accordance with the present invention, for the surface treatment of aluminum metals is a surface treatment bath entrained by water which forms a conversion coating on the surface of aluminum metals and is characterized in that it has a pH of 1.5 to 4.0 and comprises, preferably consists essentially of, or more preferably consists of water and the following components: (A) at least one phosphoric acid compound, (H) at least one oxycodone, (C) at least one oxidizing agent, and (D) at least one compound that is a source of hydrogen fluoride, in an amount that produces a total concentration of hydrogen fluoride in aqueous solution in the range from 0.0001 to 0.2 grams per liter (hereafter is usually abbreviated as "g / 1".

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS The aforementioned hydrogen fluoride generating compound in the surface treatment composition according to the present invention is preferably selected from hydrofluoric acid and ammonium fluoride. The aforementioned oxidizing agent in the surface treatment composition according to the present invention preferably consists of at least one selection of hydrogen peroxide, nitrous acid, organoperoxides and salts of the foregoing. The aforementioned zirconium compound (s) are preferably present in a composition for the surface treatment according to the present invention in a total concentration of 0.004 to 0.5 g / 1 as zirconium. The aforementioned phosphoric acid compound (s) is preferably present in a composition for the surface treatment according to the present invention at a concentration of 0.005 to 0.4 g / 1 as Po 3 ions. The equivalent total stoichiometry as ions PO4"3 of all orthophosphoric acid (ie, H3PO4), raetaphosphoric acids (ie [HP0] x where x is a positive integer with a value of at least 3), and condensed phosphoric acids ( that is, H (2) PnO (.-m + i) where n is a positive integer with a value of at least 2) and any of the anionic products that are formed by dissociation of any of these acids, including anions added to the composition in the form of salts, must be understood as constituents of the P ion content? J for the definition of this concentration, independent of the actual degree of ionization, dissociation and / or association that may occur in the composition for the surface treatment. The aforementioned oxidizing agent is preferably present in the composition for the surface treatment, according to the present invention, in a concentration of 0.01 to b / g / 1. A process in which sedimentation is largely inhibited, in accordance with the present invention, for the treatment of aluminiferous metal substrate surfaces is characterized by the formation of a conversion coating on the surface of aluminum metals by contacting the surface for 0.5 to 60 seconds with a treatment bath containing some composition for the surface treatment as directly described above and then, optionally, subjecting the surface to a rinse with water and drying. When the surface treatment agents of the prior art, with their relatively low reaction rates, are sprayed onto an article formed as aluminum EP cans, the resulting conversion coating will usually not be uniform, due to the differences in the flow velocity of the bath and the bath / surface contact conditions that occur between different regions. The conversion coating can therefore exhibit irregular performance. In the specific case of aged surface treatment solutions in which the concentrations of aluminum ions in the solution have reached high levels, fluorine is consumed from the zirconium fluorocomplex and it is necessary to add an additional fluorine source to maintain the zirconium stably dissolved in the bath, that is, to keep the treatment bath transparent. This causes an even more pronounced variation in the weight of the coating between the various reactions of the can.

The inventors discovered that the speed of the conversion coating formation reactions and the uniformity of the conversion coating can be improved by the presence of HE - in addition to zirconium, phosphoric acid and oxidizing agents - for the purpose of stabilizing the quality by eliminating the variations in the coating weight between the regions of an article formed, which would otherwise arise from the differences in the reaction rate. It was also found that the management of the HF concentration from 0.Ü01 to 0.2 g / i to inhibit the precipitation of zirconium in the treatment bath gives rise to an improved inhibition of sediment formation even in the case of treatment baths. aged that have high concentrations of aluminum ions. It is believed that coating formation occurs during treatment with a zirconium-containing treatment bath due to an increase in pH at the interface between the metal substrate and the treatment bath. On the other hand, in relation to the hydrofluoric acid and the aluminum fluorocomposites present in the conversion treatment baths, it is known that the structures of these compounds change as a function of the pH of the treatment bath. Free fluoride (F ~), hydrofluoric acid (HF), and various aluminum fluorocompounds may be present in an aqueous acid solution containing aluminum and fluorine. These proportions vary with variations in the pH of the aqueous solution. Conversion coating formation reactions are believed to occur due to the decrease in HF concentration in the vicinity of the interface. Therefore, it becomes necessary to control the concentration of the HF in the treatment bath to maintain a high conversion activity and a transparent appearance in the treatment bath. In the present invention the concentration of HF is measured as follows. First a commercially available fluoride ions reference solution is diluted with a commercially available solution to adjust the ionic concentration / pH, in order to prepare three reference solutions with the following concentrations of F ions: "F-1" mg / 1, F 10 g / i and F 100? mj / 1. These solutions are then equilibrated at the specified temperature and used to calibrate the measurement values of a fluoride ion meter.A sample of the surface treatment solution then it equilibrates to the specific temperature and its concentration of F "is obtained using the calibrated fluoride ion meter and the conversion is made to the molar concentration, determined as" [F ~] ". The pH of the treatment bath is also measured in the molar concentration of Hf determined as "[H1]" which is derived therefrom. The molar concentration of HF, determined as "[HF]", is then calculated from the known dissociation constant for HF according to the following equation [HF] =. { [H +] # [F ~ J / 10"3-1 '.} The value [HF] thus obtained becomes ag / 1 multiplied by the gram molecular weight of HF The following concentrations are preferred for the composition of surface treatment according to the present invention: zirconium composition 0.005 to 0.5 g / 1 as zirconium, for the compound phosphoric acid 0.005 to 0.4 g / 1 as ions P04, for the oxidizing agent 0.01 to 5 g / 1. with the concentrations of the phosphoric acid compound, zirconium compound and oxidizing agent in the composition for the surface treatment in accordance with the present invention, if any of these is below the lower limits specified in the above, the resulting treatment bath it will have an inadequate conversion coating formation activity and may not be able to deposit a conversion coating of sufficient thickness.No further increase in effect is obtained when these concentr tions exceed the above-specified upper limits, and therefore these concentrations only serve to raise the cost.

The zirconium-containing pellet is easily produced when the concentration of the hydrogen fluoride source compound in the composition for the surface treatment according to the present invention is below 0.0001 g / l as HF (hydrogen fluoride). When this value exceeds 0.2 g / 1, there is an excessive attack or taxation that prevents the formation of a conversion coating. A process for the surface treatment according to the present invention consists of the formation of a coating of cmivor; i ?? punicinlu on c iitoctv) the target surface of the aluminiferous metal substrate with a treatment bath containing the composition for the treatment as described above, and then, optionally but preferably, therein rinsing with water and drying. This contact between the treatment bath and the metal surface can be implemented using spray or immersion technology, as a one-step process or as an intermittent multi-step process. The total contact time preferably should be from 0.5 to 60 seconds. Because the composition of the specific component of the treatment bath is capable of inhibiting the adhesion of the sediment in the equipment, the process described according to the present invention can achieve excellent operating stability and high treatment efficiency. The surface treatment bath, according to the present invention, is an acid treatment bath containing phosphate ions, a zirconium compound, fluoride and oxidizing agent as its essential components. The source of the phosphate ions in this treatment bath is preferably phosphoric acid, ammonium phosphate and / or an alkali metal salt of phosphoric acid, with phosphoric acid and ammonium phosphate as the most preferred, taking into consideration the sediment inhibition. The preferred content is 0.005 to 0.5 g / 1 as phosphate ions (PO4), while the range of 0.01 to 0.20 g / 1 as phosphate ion is even more preferred. The concentrations of phosphate ions below 0.005 g / 1 result in poor reactivity which makes the formation of satisfactory coatings very difficult. At the other extreme, no additional benefit is obtained with concentrations in excess of 0.4 g / 1, which therefore only serve to raise the cost of the composition for the treatment and in this way is economically undesirable. The presence of the zirconium compound in the treatment baths according to the present invention is more advantageous by the use of water-soluble zirconium compounds, more preferably water-soluble fluorozirconium complexes and still more preferably fluorozirconic acid (H? ZrFfo) and its salts. With regard to the use of zirconium oxide, hydroxide, nitrate or phosphate, this must be done by the use of zirconium oxide, hydroxide, nitrate or zirconium phosphate. i mu i t onoo tl < ? (luoruro) provides the hydrogen fluoride in sufficient quantity to transform the zirconium into water-soluble fluorocomplex and thereby prevent the production of a precipitate.The content of the zirconium compound is preferably from 0.005 to 0.5 g / 1 as zirconium and more preferably from 0.01 to 0.1 g / 1 as zirconium It is possible that adequate film formation with a zirconium content below 0.005 g / 1 will not occur No additional benefit is obtained in concentrations in excess of 0.5 g / 1 , which therefore only serve to raise the costs of the treatment bath and thus are economically undesirable The presence of hydrogen fluoride in the treatment bath, according to the present invention, is more advantageously achieved by adding hydrofluoric acid or ammonium fluoride, the preffered HF content is in the range of 0. 0001 a (). '/ > q / I y o ipo or tolerencio ontro in o] range of »0.01 to 0.1 g / 1. The oxidizing agent present in the treatment bath according to the present invention is exemplified with hydrogen peroxide, nitrous acid and its salts in organoperoxides. The use of hydrogen peroxide is more preferred, based on a consideration of the ease of treatment of the wastewater that is produced by the process according to the present invention. The oxidizing agent works to accelerate the speed of the reactions that produce the zirconium coating. The content of the oxidizing agent is preferably 0.01 to 5 g / 1 and more preferably 0.1 to 1.0 g / 1. The accelerating activity of the reaction may be unsatisfactory at concentrations of the oxidizing agent below 0.01 g / 1. No problem is associated with concentration in excess of 5 g / 1, but these concentrations do not provide any additional benefit, and therefore only raise costs and are economically undesirable. The pH of the treatment bath should be adjusted from 1.5 to 4.0. The degree of etching becomes excessive at pH values below 1.5 and prevents the formation of the conversion coating. The etching becomes too weak with pH values in excess of 4.0 and hinders the formation of a coating highly resistant to corrosion. The preferred pH range is from 2.3 to 3.0. The pH can be adjusted by the use of an acid such as phosphoric acid, nitric acid or hydrochloric acid or by the use of an alkali such as ammonium hydroxide, ammonium carbonate or sodium hydroxide. Phosphoric acid and nitric acid are the preferred acids for pH adjustment, while basic ammonium compounds are preferred as the alkali. The stability of the composition for the treatment can be substantially imparted by the metal ions, such as those of copper, manganese and the like which are produced when the alloying component is eluted from the surface of the aluminum aluminus substrate. This can result in these problems such as sediment production, precipitate formation and the adhesion of the sediment and / or and the precipitate in the equipment and the like. To prevent this from happening, an organic acid or salt thereof can be added, for example, gluconic acid, oxalic acid and its salts to chelate these components and stabilize the bath. A water soluble fluorocomplex, for example, of titanium, silicon and the like can also be added to the surface treatment bath, in accordance with the present invention together with the zirconium compound, for example, a water soluble fluorozirconium complex. An example of the surface treatment process, according to the present invention, for a metallic aluminum substrate includes the following steps: (1) surface cleaning: degreasing (acid, alkaline or solvent based degreasers can be used) ( 2) water rinsing (3) the conversion coating treatment (surface treatment using a treatment bath in accordance with the present invention) (4) rinse with water (5) rinse with deionized water (6) drying The temperature for the treatment with the surface treatment bath according to the present invention is not critical, and a temperature range, for example, can be used from room temperature to 90 ° C. However, taking into consideration the stability, the operating behavior and the productivity characteristics of the treatment bath, the bath is preferably used from 25 to 50 ° C. The treatment time is not critical, but treatment times of, for example, 0.5 to 50 seconds are preferred and the range of 5 to 30 seconds is even more preferred. A complete reaction is usually not obtained in less than 5 seconds; this would avoid the formation of a coating highly resistant to corrosion. At the other end of the range, no additional increase in performance has been observed in times above 60 seconds. The bath and the process for surface treatment according to the present invention will be illustrated through the working examples provided below.

Examples The following samples and performance evaluation tests were used in Work and Comparative Examples. (1) Samples The materials were aluminum alloy sheets (A3004) and aluminum EP cans made from these types of aluminum alloy sheets. Each of these was cleaned, prior to the surface treatment according to this invention, with a hot aqueous solution of an acid degreaser (PALKLIN® 500, a product of Nihon Parizing Company, Limited, Tokyo). (2) Evaluation methods (a) Corrosion resistance and coating uniformity The corrosion resistance and the uniformity of the coating were evaluated in EP cans of aluminum based on the resistance to the blackening by boiling water. The resistance to blackening by boiling water was tested as follows. After the surface treatment, the aluminum EP cans were immersed in boiling tap water for 30 minutes. This was followed by a visual determination of the degree of discoloration (blackening) produced by this in the elevations (reqiones where the flow velocity of the bonus Ioo t) and Jupie;, where the velocity of the bath flow was slow) of aluminum EP cans. These elevations correspond to the flange and regions of the outer side wall of the real aluminum EP cans while * that the depression corresponds to the region of the dome. The corrosion resistance was evaluated by recording the results of the test on the following scale: + = no blackening @ = blackening on one part of the surface X = blackening on the entire surface uniformity of the coating was classified as follows based on site specific evaluation of resistance to blackening with boiling water: a "uniform" record was generated when both locations were free of blackening, while a "non-uniform" record was generated when blackening occurred in only one place . (b) Adhesion of the paint After the aluminum alloy sheet (A3004) had been subjected to the surface treatment it was coated with an epoxy-urea grade paint to give a paint film thickness of 5 to 7 microns. This was followed by baking and drying to give a painted panel. A test panel was then prepared by folding the painted panel into a bending tester, and this test panel was subjected to a peel test using a cellophane tape. The results of the test were recorded as: I + = no peeling occurred X = peeling occurred (c) transparency of the bath the treatment bath that had been used in the specific example or the comparative example was maintained at 40 ° C for 15 minutes. days. The amount of zirconium in the bath was measured before and after this period and the presence / absence of precipitate was determined from the difference of these values. A "+" indicates that no precipitate occurred, while "X" indicates that precipitate occurred. (d) Confirmation test for the adhesion of the sediment The treatment bath that had been used in the particular example or the comparative example was continuously supplied for 16 hours for the spray treatment using a small-scale sprinkler that was maintained at 40 °. C. During this time, the development of sediment in the nozzle of the device was visually inspected. A "+" indicates that there was no sediment adhesion, while "X" indicates that sediment adhesion occurred. Example 1 The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 20 seconds with the surface treatment bath (1) (composition given below) heated to 40 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint. Aluminum nitrate was used as an aluminum source for the purpose of artificially aging the treatment bath.

Surface treatment bath (1) phosphoric acid 30 ppm as P0 ions fluozirconic acid 30 ppm as Zr hydrogen peroxide 100 ppm as H202 aluminum nitrate 100 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) concentration of HF = 11 ppm (adjusted with hydrofluoric acid). Example 2 The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 40 seconds with the surface treatment bath (2) (composition described below) heated to 40 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath (2) 20 ppm phosphoric acid as P04 ions fluozirconic acid 10 ppm as Zr hydrogen peroxide 300 ppm as H202 aluminum nitrate 50 ppm as Al pH = 2.7 (adjusted with aqueous ammonia) concentration of HF = 9 ppm (adjusted with hydrofluoric acid). Example 3 The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 15 seconds with the surface treatment bath (3) (composition described below) heated to 40 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath (3) phosphoric acid 40 ppm as ions ü fluozirconic acid 40 ppm as Zr hydrogen peroxide 200 ppm as H202 aluminum nitrate 200 ppm as Al pH = 2.3 (adjusted with aqueous ammonia) concentration of HF = 15 ppm (adjusted with hydrofluoric acid). Example 4 The clean aluminum EP cans and the clean aluminum alloy sheets were immersed for 10 seconds with the surface treatment bath (4) (composition described below) heated to 30 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint. Surface treatment bath (4) phosphoric acid 150 ppm as P04 ions fluozirconic acid 100 ppm as Zr hydrogen peroxide 400 ppm as ti 0? aluminum nitrate 300 ppm as Al pH = 2.5 (adjusted with aqueous ammonia) concentration of HF = 70 ppm (adjusted with hydrofluoric acid). Example 5 The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 5 seconds with the surface treatment bath (5) (composition described below) heated to 30 ° C. This was followed by the rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath 400 ppm phosphoric acid as P04 ions Ammonium fluozirconate 200 ppm as Zr hydrogen peroxide 500 ppm as H? 02 aluminum nitrate 500 μpm as Al pH = .5 (adjusted with aqueous ammonia) concentration of HF = 100 ppm (adjusted with hydrofluoric acid). Example 6 the clean aluminum cans EP and the clean aluminum alloy sheets were sprayed for 15 seconds with the surface treatment bath (6) (composition quo described or ront inunción) cal ntado o 40 ° C, Kr.to was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath (6) phosphoric acid 50 ppm as ions P04 zir oxide zir, tO ppm as Zr hydrogen peroxide 200 ppm as H202 aluminum nitrate 200 ppm as Al pH = 2.3 (adjusted with aqueous ammonia) concentration of HF = 13 ppm (adjusted with hydrofluoric acid). Example 7 The clean aluminum cans EP and the clean aluminum alloy sheets were sprayed for 15 seconds with the surface treatment bath (7) (composition described below) heated to 40 ° C. This was followed by the rinsing with running water, the spray rinse for 10 seconds with deionized water and then the drying in norno of drying with hot air. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath (7) phosphoric acid 50 ppm as ions P04 zirconium oxide 30 ppm as Zr hydrogen peroxide 200 ppm as H202 aluminum nitrate 100 ppm as Al pH = 3.5 (adjusted with aqueous ammonia) concentration of HF = 7 ppm (adjusted with hydrofluoric acid). Comparative Example 1 The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 10 seconds with the surface treatment bath (8) (composition described below) heated to 40 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evacuated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath (0) (without oxidizing agent) 30 ppm phosphoric acid as PQ4 ions 30 ppm fluozirconic acid as Zr aluminum nitrate '200 ppm as Al pH = 3.5 (adjusted with aqueous ammonia) concentration in cl II - 15 ppm (used with hydrofluoric acid). Comparative example 2 The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 10 seconds with the surface treatment bath (9) (composition described below) heated to 50 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath -?) (Without zirconium compound) 50 ppm phosphoric acid as P04 hydrofluoric acid ions 220 ppm as F hydrogen peroxide 500 ppm as H.JO; 100 ppm aluminum nitrate as Al pH = 2.5 (adjusted with aqueous ammonia) concentration of 111 '' - 10 ppm (adjusted with hydrochloric acid). E, omp I i i such a field. > The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 20 seconds with the surface treatment bath (10) (composition described below) heated to 35 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained are evacuated to: e :: s ~: es - te: c_a a -a co:: os: o. "., uniformity of coating and adherence of paint.

Surface treatment bath i, '0) fluoromirconic acid 40 ppm as Zr hydrogen peroxide 500 ppm as H ^ O aluminum nitrate 200 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) concentration of HF = 50 ppm (adjusted with hydrofluoric acid) . Comparative example 4 The cans 'i "u J', iiio .. iupj.it, and the clean aluminum alloy sheets were sprayed for 15 seconds with the surface treatment bath (11) (composition described below) heated at 40 ° C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water and then drying in a hot air drying oven.The samples thus obtained were evaluated for their corrosion resistance, uniformity of the coating and adherence of the paint.

Surface treatment bath (II) phosphoric acid 50 ppm as ions P04 fluozirconic acid 50 ppm as Zr hydrogen peroxide 300 ppm as H0; aluminum nitrate 200 ppm as Al pt: -, '. / t.ii? .. hi? K •. c a¡ '! :: i a », or aqueous) concentration of n.F - •• 0.05 ppm (adjusted with hydrofluoric acid). Comparative example 5 The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 10 seconds with the surface treatment bath (12) (composition as described above) heated to 0CC. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath (12) phosphoric acid 40 ppm as P0 oxo ions of Y.? r c > . 4 ppm as Z. hydrogen peroxide 300 ppm as h0 ^ aluminum nitrate 200 ppm as Al pH = 2.8 (adjusted with aqueous ammonia) concentration of HF = 0.01 ppm (adjusted with hydrofluoric acid). Comparative example 6 Jl The clean aluminum EP cans and the clean aluminum alloy sheets were sprayed for 15 seconds with the surface treatment bath (13) (composition described below) heated to 40 ° C. This was followed by ei. rinse under running water, spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples thus obtained were evaluated in their resistance to corrosion, uniformity of the coating and adherence of the paint.

Surface treatment bath (13) phosphoric acid 40 ppm as ions 04 fluozirconic acid 40 ppm as Zr alurrum nitrate 300 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) concentration of HF = 15 ppm (adjusted with hydrofluoric acid). Comparative example 7 The clean aluminum cans EP and the clean aluminum alloy sheets were sprayed for 30 seconds with the surface bonding bath (14) (composition described below) heated to 40 ° C. This was followed by rinsing with running water, the spray rinse for 10 seconds with deionized water and then drying in a hot air drying oven. The samples obtained in this way are evaluated for their resistance to corrosion, uniformity of coating and adherence of the paint.

Surface treatment bath i 1) 100 ppm phosphoric acid as P0 ions fluozirconic acid. 100 ppm as Zr 300 ppm aluminum nitrate as Al pH = 3.0 (adjusted with aqueous ammonia) HF concentration = 20 ppm (adjusted with hydrofluoric acid). The results of: < ? Eba from all the examples and comparative examples were recorded in table 1. Examples 1 to 7 used a surface treatment bath and surface treatment processes according to the present invention, and table 1 confirms The following results of these examples: the conversion coatings obtained showed an excellent resistance to corrosion and adhesion to the paint; the conversion coatings obtained were very uniform; the surface treatment baths maintained their transparency; and the adhesion of sediment was completely inhibited. In contrast, comparative examples 1 to 7 - which used surface treatment baths outside the scope of the invention - in each case gave a general performance insat i sfactopo since all were deficient in at least one aspect (resistance to corrosion, adhesion of the paint, uniformity of the conversion coating, transparency of the treatment bath and inhibition of the adhesion of sediment). The composition of the surface treatment and the "slow cure process" according to the present invention impart excellent corrosion resistance and excellent adhesion of the paint on the surface of aluminum-based substrates prior to the painting process of these substrates. Other desirable effects demonstrated by this composition and process are a very uniform conversion coating, excellent transparency of the treatment bath and an excellent inhibition of thirst adhesion, These characteristics confer a high degree of practical utility to the bath and process according to the present invention for treating the surface of aluminiferous metal substrates Table 1 Abbreviations in the table: "Ahem." = Example "EC" - "Comparative example"

Claims (1)

1. CLAIMS An aqueous liquid composition highly inhibiting sedimentation for surface treatment of metals to UJ? Nll ei, osla composition has a pll from 1.5 to 4.0 and contains water and: (A) at least one phosphoric acid compound , (B) at least one zirconium compound, (C) at least one oxidizing agent, and (D) at least one compound that is a source of hydrogen fluoride, in an amount that produces a total concentration of hydrogen fluoride in an aqueous composition in the range of 0.0001 to 0.2 g / 1 or composition li ^. a a ... osa, according to claim., wherein the component (D) is selected from the group consisting of hydrofluoric acid, ammonium fluoride, and mixtures thereof. The aqueous liquid composition according to claim 2, wherein the component (C) is selected from the group consisting of hydrogen peroxide, nitrous acid and its salts, organoperoxides and mixtures of two or more of the previous ones. The aqueous liquid composition according to claim 1, wherein the component (C) is selected from the group consisting of hydrogen peroxide, acid or nitrogen and their salts, organoperoxides and mixtures of any two or more of The above The aqueous liquid composition, according to claim 4, wherein the concentration of the component (3) is from 0.005 to 0.5 g / 1, measured as zirconium. The aqueous liquid composition according to claim 3, wherein the concentration of component (B) from J.005 to O.b g / i, measured as zirconium. The aqueous liquid composition, according to claim 2, wherein the concentration of component (B) is from 0.005 to 0.5 g / 1, measured as zirconium. The aqueous liquid composition, according to claim 1, wherein the concentration of. component (3) is from 0.00o to 0.5 g / 1, measured as zir with i o. The composition . Iqu.da ac-osa, according to claim b, in which the concentration of the component (A) is from 0.005 to 0.4 g / 1, as ions PO,. The aqueous liquid composition, according to claim 7, wherein the concentration of component (A) is from 0.005 to 0.4 g / 1, as P04 ions. 11. The aqueous liquid composition, according to claim b, in which the concentration of the component (A) is from 0.0000 n 0.4 g / 1, as PO ions,. 12. The aqueous liquid composition, according to claim 5, wherein the concentration of the component (?) From 0.005 to 0.4 q / 1, as O, ions. 13. The aqueous liquid composition according to claim 4, wherein the concentration of the component (A) is from 0.005 to 0.4 g / 1, as PO ions,. 14. The aqueous liquid composition, according to claim J, wherein the concentration of component (A) is from 0.005 to 0.4 g / 1, as FU ions. 15. The aqueous composition according to claim 2, wherein the concentration of the component (A) s from 0.005 to 0.4 g / 1, as P ions,. 16. The aqueous liquid composition, according to claim 1, wherein the concentration of component (A) is from 0.005 to 0.4 g / 1, as O, ions. The aqueous liquid composition according to any of claims 1 to 16, wherein the concentration of the component (C) is 0.01 to 5.0 and / i. A process for forming a protective conversion coating on an aluminiferous substrate surface, this process comprises contacting the surface of the substrate with an aqueous liquid composition according to claim 17 for from 0.5 to segundos seconds, and optionally, then subjecting the substrate surface to an opjuage ion here.j and so..jd < > . A μi c S '.. or' < •; • a i! ,.; In my protective conversion method on an aluminiferous substrate surface, this process comprises contacting the surface of the substrate with an aqueous liquid composition according to any of claims 1 to 16 for from 0.5 to 60 seconds, and optically, then submit the suporicio do r '. St i J o to a rinse with water and drying. LIELUIMEN l E I.? INVENTION The present invention relates to a conversion coating highly resistant to corrosion and strongly adherent to the paint that forms on the surface of aluminum metallic substrates upon contacting these surfaces for 0.5 to 60 seconds with bath, surface treatment with water-based and sediment-free base which has a? 5 to 4.0 and which contains r. composed of iron, phosphoric acid, oxidizing agent and a compound that is a source of hydrogen fluoride (in an amount that produces a concentration of HF from 0.0001 to 0.2 g / l in the treatment bath). This contact preferably is followed by a rinse with water and drying.