BR112016017018B1 - METHOD FOR COATING METALLIC SURFACES, THEIR COATED SUBSTRATES AND THEIR USE - Google Patents

Abstract

METHOD FOR COATING METALLIC SURFACES, THEIR COATED SUBSTRATES AND THEIR USE The invention refers to a method of coating metallic surfaces with an aqueous acidic conversion composition, which contains: in total 0.01 to 1 g/L of TiF62+, ZrF62+ and/or HfF62 calculated as ZrF62+, 0 or 0.01 to 1 g/L respectively of Fe2+-, Mn- and/or Zn ions, of which at least one type of these ions is present in the content range of 0, 01 to 1 g/L, 0 or 0.01 to 2 g/L of polymer and/or organic copolymer, 0 or 0.01 to 2 g/L of SiO2 in very fine particles, of about 0 or 0.01 to 10 g/L of at least one surfactant, about 0 or 0.05 to 10 g/L of anions made from Carbonate, Nitrate and/or Sulfate, and 0 or 0.001 to 2 g/L of carboxylate anions and /or sulfonate, the molybdate and/or oxyanion content containing P being respectively < 0.1 g/L or about 0 g/L and the composition having a pH value in the range of 2.5 to 6.5. The invention also relates to a corresponding coating and the use of substrates coated therewith.

Description

[001] The invention relates to a method of coating metallic surfaces with a colored conversion layer if necessary especially for the application of an alkaline phosphatization such as, for example, an iron-based phosphatization, substrates correspondingly coated with surfaces metals as well as the use of these coated substrates.

[002] Methods for manufacturing alkaline phosphate based coatings, especially as preliminary treatment layers before painting, have been separately described. Alkaline phosphate solutions not yet used normally have practically no, or only very rarely, a minimum content of aluminium, iron and zinc. Aqueous acidic alkali phosphate solutions in addition to ions of at least one alkali metal and/or ammonium also contain phosphate ions and, due to the corrosive effect of these solutions on metallic surfaces, ion contents of the metals separated from the metallic surfaces, e.g. aluminum, iron and/or zinc as well as traces of alloy components of corroded metallic materials. The phases formed mainly during alkaline phosphatization in the alkaline phosphate layer are the corresponding phosphates, oxides and/or hydroxides of the metals originating from the surfaces of the base substrates to be treated.

[003] Alkaline phosphate solutions or coatings are also called when applying iron-based phosphate solutions or coatings to iron and steel materials. Alkaline phosphate coatings are designated According to Werner Rausch: Die Phosphatierung von Metallen, Saulgau 1988 (see especially pages 109 - 118), in general also as layers of so-called "non-layer-forming phosphatization". This designation is misleading, since also in this case layers are formed which, however, are much thinner than other phosphate layers, such as the different types of zinc phosphatizations. The alkali phosphate solution always contains a high content of at least one alkali metal such as, for example, sodium and/or ammonium.

[004] Alkaline phosphatizations can largely be carried out in a simple and inexpensive way. High quality alkali phosphate coatings show however despite the second post conversion treatment only limited corrosion protection, normally a) corrosion protection of no better than, i.e. less than 3 mm infiltration, tested in the corrosion test. salt spray test according to DIN 50021 NSS above 500 hours in the case of electrostatic powder coating based on epoxy-polyester powder coating 60 to 80 μm thick on a sheet metal made of laminated steel normally b) corrosion protection not better than, i.e. not less than 4 mm infiltration, verified in the salt spray test in accordance with DIN 50021 NSS for 500 hours in a base coat wet paint of 60 to 80 μm thick polyurethane-isocyanate lacquer on a sheet metal made of cold-rolled steel and usually c) a paint adhesion of not better than, i.e. not less than, GT 3 in an adhesion test debonding proof in 240 hours of testing according to the KK test according to DIN EN ISO 2409 in an electrostatic powder coating based on epoxy-polyester powder lacquer 60 to 80 μm thick on a sheet metal made of cold rolled steel.

[005] For this reason it is normally necessary in alkaline phosphatizations to apply a second coat of conversion applied additionally and to a large extent still at least one coat of paint applied afterwards. Such multi-stage methods are not only very expensive, but require additional baths and/or treatment zones as well as additional spraying steps and/or drying steps and are also costly and time consuming. Often the paint adhesion of the alkali phosphate coating is also insufficient so that it is necessary to carry out an additional conversion coating, for example based on zirconium hexafluoride and/or silane, before applying the paint. Thus the coating method is especially expensive and expensive. The disadvantage also lies in the high phosphate content of alkaline phosphatizations, as the phosphate has to be disposed of in wastewater at a high cost.

[006] A multi-stage alkaline phosphatization is often applied, in the first stage the cleaning is done primarily and in the second stage the formation of a layer occurs. Then washing or further washing is done.

[007] There was the task of finding aqueous compositions that could be applied more easily that were composed in the most environmentally friendly way possible and produced the highest corrosion protection as high quality alkali phosphate coatings.

[008] The task is solved with a method for coating metallic surfaces with an acidic aqueous conversion composition which is a solution or dispersion that is characterized by the fact that it contains:

[009] in total 0.01 to 1 g/L of TiF62+, ZrF62+ and/or HfF62+ in the form of ions calculated as ZrF62+,

[0010] 0 or 0.01 to 1 g/L respectively in Fe2+-, Mn- and/or Zn ions, of which at least one type of these ions is present in the content range of 0.01 to 1 g/L ,

[0011] where preferably Mn- and/or Zn ions are present,

[0012] 0 or 0.01 to 2 g/L an organic polymer and/or copolymer, which is stable at a pH value < 6.5, referring to the solid matter content,

[0013] 0 or 0.01 to 2 g/L of particular SiO2 with an average particle diameter < 0.3 μm, measured in a scanning electron microscope and with respect to solid matter content,

[0014] about 0 or 0.01 to 10 g/L of at least surfactant,

[0015] about 0 or 0.05 to 10 g/L of anions selected from the carbonate, nitrate and sulfate group, converted to NO3+, even though CO32+ or SO42+ are present, and

[0016] 0 or 0.001 to 2 g/L of carboxylate and/or sulfonate anions, which do not or practically do not impair the layer formation, computed as the corresponding anions,

[0017] being that the content of molybdate computed as MoO42+ and/or the content of oxyanions containing P calculated as PO43+ respectively < 0.1 g/L or approximately 0 g/L and the acidic aqueous composition has a pH value in the range of 2.5 to 6.5 and preferably in the range of 3.0 to 5.5.

[0018] TiF62+, ZrF62+ and/or HfF62+ ions are in the acidic aqueous conversion composition largely monovalent and replaceable but often the ZrF62+ ions produce the best properties of the conversion coating produced here. Preferably, the content of the TiF62+, ZrF62+ and/or HfF62+ aqueous acid conversion composition is 0.05 to < 1 g/L, 0.1 to 0.8 g/L, 0.15 to 0.50 g/L or 0.20 to 0.33 g/L.

[0019] In this case, it is preferred that in a cation content of the aqueous acidic conversion composition only in Fe2+ ions with respect to the total content of Fe2+-, Mn- and Zn ions that content is due at least in part to an intentional addition . The manganese and zinc ions as well as in a limited scope also Fe2+ are in the aqueous acidic conversion composition largely monovalent and replaceable, but often the manganese and/or zinc ions produce the best properties of the conversion coating generated here. . If manganese and zinc are added to the acidic aqueous conversion composition, it is especially preferred to obtain a manganese content that is higher than the zinc content. Preferably it contains 0 or 0.01 to 0.3 g/L or 0.02 to 0.15 g/L of Fe2+- ions as well as 0.01 to 1 g/L of Mn and/or 0. 01 to 1 g/L or 0.1 to 0.6 g/L of Zn ions. It especially preferably contains 0.1 to 0.6 g/L or 0.2 to 0.4 g/L of Mn ions and/or 0.1 to 0.6 g/L or 0.2 to 0.4 g/L of Zn ions.

[0020] It is preferred to work basically phosphate free (< 0.1 g/L PO4) or totally phosphate free (about 0 or exactly 0 g/L PO4). In the case of individual method variants, a phosphate content calculated with PO43+ between 0.001 and < 0.1 g/L cannot be ruled out, especially due to introductions and impurities. Furthermore, it is also preferred to work basically phosphonate-free (< 0.1 g/L PxOy) or totally phosphate-free (about 0 or precisely 0 g/L PxOy) phosphonate-free.

[0021] An addition of organic polymer and/or organic copolymer can contribute to the properties of the conversion coating produced being even more improved and that, if necessary, it is possible to dispense with a subsequent painting application. Preferably, the content of the aqueous acid converting composition of organic polymer and/or organic copolymer is 0.01 to 3 g/L, 0.1 to 2.5 g/L, 0.2 to 2 g/L, 0.4 to 1.5 g/L or 0.6 to 1.2 g/L. The organic polymer and/or copolymer is preferably a copolymer based on (meth)acrylate/(meth)acrylic acid and/or vinylacetate-acryl.

[0022] When dispensing with an application of paint, we can speak in the case of coating produced from a passivation layer and in the case of corrosion protection without coating.

[0023] An addition of SiO2 of finer particles (especially < 0.3 μm) such as SiO2 nanoparticles can show a similar positive action as an addition of organic polymer and/or organic copolymer but often with the difference that the layer formation and therefore the SiO2 coating is even more uniform.

[0024] It is possible to basically add respectively at least one non-ionic, anionic, and/or zwitterionic surfactant. An addition of at least one non-ionic surfactant is preferred in this case especially.

[0025] An addition of anions selected from the group consisting of carbonate, nitrate and sulfate is often done by adding cations over water-soluble salts. In this case, nitrates are especially preferred.

[0026] An addition of carboxylate anions such as, for example, through acetic acid and/or through manganese carboxylate is as an alternative or complement to these anions basically possible and often well suited, to avoid or decrease acid anions minerals. Basically all types of carboxylic acids and their derivatives such as salts and esters can be added, which are water-soluble, which are stable in the pH value range, which have complicated substance composition, which form anions in water, which do not harm depending on the type and quantity of the anions, the formation of a layer and which, if necessary, complex alkali metal and/or alkaline earth ions, which do not participate in the formation of the layer. They are especially aliphatic carboxylic acids and mono, di- and/or polycarboxylic acids, such as, for example, hydroxycarboxylic acids. In the case of the addition of carboxylate anions, attention should be paid to the fact that these do not impair the formation of the layer, for example, citrate and other individual complexing agents may eventually impair the formation of the layer, depending on the type and amount of anions.

[0027] In this case, an addition of at least one sulfonic acid such as, for example, methanesulfonic acid, amidosulfonic acid and/or a derivative thereof is favorable to act as accelerators and/or as another counterion.

[0028] Basically a molybdate content calculated as MoO4 is 0 or in the range of 0.01 to < 0.5 g/L, especially from 0.02 to 0.3 or g/L, from 0.01 to < 0.1 g/l preferably. An addition of molybdate proved successful only in very small amounts of addition.

[0029] An addition of P-containing oxyanions such as orthophosphate, phosphonates and condensed phosphates should be avoided especially due to a possible waste water load and possibly also due to a stronger sludge formation which can lead to an expensive final disposal. of wastewater and/or sludge. Especially in the case of P-containing oxyanions it is preferred for reasons of compatibility with the environment and to avoid final disposal effort that no content of P-containing oxyanions is added and care must be taken to ensure that the maximum possible content of P is not introduced. oxyanions containing P.

[0030] In the case of the method according to the invention, it is preferred that the acidic aqueous composition optionally also contains, basically composed of or composed of:

[0031] 0.03 to 5 g/L of the sum of lithium, sodium and/or potassium ions, 0 or 0.05 to 5 g/L of ammonium ions, about 0 or 0.05 to 0.3 g/L of the sum of Co- and/or Ni-ions, respectively 0 or 0.01 to 0.8 g/L of chlorate calculated as CIO3", Nitrite calculated as NO2 and/or peroxide calculated as H2O2, 0 or 0.01 to 0.5 g/L free fluoride calculated as F" and 0 or 0.01 to 0.2 g/L vanadate ions calculated as VO43".

[0032] In principle, lithium, sodium, potassium and/or ammonium contents should normally not be avoided, in order to obtain a charge compensation and not to add only polyvalent cations such as, for example, heavy metal ions. Among the monovalent cations, sodium ions are especially preferred. They are largely equivalent and replaceable in aqueous acid conversion composition and often necessary for pH regulation.

[0033] As in many coating methods, an addition of cobalt and/or nickel is also advantageous in this case, in order to obtain better corrosion protection even if these elements are problematic with regard to environmental compatibility and work hygiene. .

[0034] An addition of at least one accelerator is often necessary, especially an addition of a chlorate, nitrite and/or peroxide. In this case, care must be taken, however, for an adequate amount, for example for a NO2 content of well less than 1 g/L. In the case of adding at least one accelerator the layer formation can be accelerated and the coating properties generated here are improved. In this case, the overdose of accelerators must be avoided so that the formation of a layer is not impaired, such as, for example, B40. An addition of nitroguanidine did not prove to be necessary.

[0035] The complexing fluoride content alone often yields a minimal free fluoride content. A content and/or addition of at least one fluoride can produce a minimally higher content of free fluoride. Often the free fluoride content, which is especially favorable for aluminum-containing surfaces, is in the range of 0.01 to 0.5 g/L, calculated as F-.

[0036] Also an addition of at least one vanadium compound can greatly increase corrosion protection.

[0037] In this case, it is not ruled out the fact that other element contents of the metallic surfaces of the substrates and installations are obtained by the corrosive action of the acidic aqueous conversion composition in the bath and eventually also accumulate in the bath composition, especially ions of Fe2+- and alloying elements or their ions.

[0038] On the other hand, in the case of current coating methods and installations, the fact that ion contents and substances made from other installation areas, for example, from a previously used cleaning step possibly despite washing with water be introduced in minimal amounts. In this way, especially amounts of alkali metals, ammonium, complexing agents, surfactants, anionic impurities from the cleaning bath and/or other impurities or their ions can be introduced into the bath composition according to the invention. A separate upstream cleaning step is, however, not absolutely foreseen so that an ingress of foreign ions through a chemical treatment solution can be largely ruled out. Favorably, a cleaning step can be carried out with water containing surfactant and without a cleaner structure content (Builder).

[0039] On the one hand the cleaning can be done before the conversion coating so that before the contact of the substrate with the aqueous composition it is cleaned, especially with an alkali cleaning. On the other hand, the aqueous composition may also contain or instead of this cleaning step also at least one surfactant so that cleaning and conversion coatings (auch) are carried out in the same process step.

[0040] Preferably, no content or only a minimum content such as respectively up to 0.1 g/L of carboxylic acids, phosphates, phosphonates and/or compounds and/or ions of calcium, chromium, chromate, cobalt, copper, magnesium, molybdenum, nickel, vanadium or/and tin and/or silane/silanol/siloxane/polysiloxane. Silane/silanol/siloxane/polysiloxane means silane, silanol, siloxane and/or polysiloxane, since in water and in the case of coating, for example, starting from a silane silanols and/or siloxanes can result very quickly, which can also sometimes - depending on the chemical definition - result in polysiloxanes.

[0041] The content of the aqueous acid conversion composition in alkaline earth metals such as calcium and/or magnesium is preferably together at most 0.2 g/L, in order to avoid as much precipitation as possible in the presence of fluorides.

[0042] Especially preferred are the following variants:

[0043] The aqueous acidic conversion composition has a pH value in the range of 2.5 to 6.5 and contains, is basically composed of or composed in its entirety: In the case of Variant A:

[0044] 0.01 to 1 g/L of TiF62+, ZrF62+ and/or HfF62+ in the form of ions calculated as ZrF62+ and

[0045] 0 or 0.01 to 1 g/L respectively of Fe2+-, Mn- and/or Zn ions, of which at least one type of these ions in the content range of 0.01 to 1 g/L is present , as well as optionally 0.01 to 2 g/L of particulate SiO2 with an average particle diameter < 0.3 μm, in relation to the solid matter content and/or optionally 0.01 to 10 g/L of at least one surfactant and in the case of a phosphate content < 0.1 g/L PO4. In the case of Variant B:

[0046] 0.01 to 1 g/L of TiF62+, ZrF62+ and/or HfF62+ in the form of ions calculated as ZrF62+,

[0047] 0 or 0.01 to 1 g/L respectively of Fe2+-, Mn- and/or Zn ions, of which at least one type of these ions in the content range of 0.01 to 1 g/L is present , and 0.01 to 2 g/L of organic polymer and/or copolymer, which with a pH- value < 6.5 is stable, with respect to the solid matter content,

[0048] as well as possibly 0.01 to 2 g/L of particulate SiO2 with an average particle diameter < 0.3 μm, with respect to the solid matter content, and

[0049] possibly 0.01 to 10 g/L of at least one surfactant,

[0050] and eventually 0.05 to 10 g/L of anions selected from the group composed of carbonate, nitrate and sulfate, converted to NO3+, even though CO32+ or SO42+ are present, and

[0051] possibly 0.001 to 2 g/L of carboxylate and/or sulfonate anions, which do not or practically do not impair the layer formation, calculated as the corresponding anions,

[0052] wherein a content of molybdate calculated as MoO42+ and/or a content of P-containing oxyanions calculated as PO43+ is respectively < 0.1 g/L or about 0 g/L. In the case of Variant C:

[0053] 0.01 to 1 g/L of TiF62+, ZrF62+ and/or HfF62+ in the form of ions calculated as ZrF62+,

[0054] 0 or 0.01 to 1 g/L respectively of Fe2+-, Mn- and/or Zn ions, of which at least one type of these ions in the content range of 0.01 to 1 g/L is present , and a molybdate content calculated as MoO42+ in the range of 0.01 to < 0.5 g/L as well as optionally 0.01 to 2 g/L of organic polymer and/or copolymer, which is stable at a pH value < 6.5 with respect to solid matter content, and eventually 0.01 to 2 g/L of particulate SiO2 with an average particle diameter < 0.3 μm with respect to solid matter content, and

[0055] possibly 0.01 to 10 g/L of at least one surfactant,

[0056] and eventually 0.05 to 10 g/L of anions selected from the carbonate, nitrate and sulfate group, converted to NO3+, even though CO32+ or SO42+ are present, and

[0057] optionally 0.001 to 2 g/L of carboxylate and/or sulfonate anions, which do not or practically do not impair the layer formation calculated as corresponding anions,

[0058] where a content of molybdate calculated as MoO42+ is in the range of 0.01 to < 0.5 g/L and a content of oxyanions containing P calculated as PO43+ < 0.1 g/L or about 0 g/l

[0059] In all three variants it is preferred that Mn- and/or Zn ions are added while the Fe2+ ion content is separated only by the corrosive effect of the acid conversion composition of the iron-rich metallic substrate. Eventually, the coating is then painted at least once.

[0060] Especially preferred is an aqueous acidic conversion composition, which is a solution or dispersion that contains, is composed primarily of or is composed entirely of:

[0061] 0.01 to 1 g/L of TiF62+, ZrF62+ and/or HfF62+ in the form of ions calculated as ZrF62+,

[0062] 0 or 0.01 to 1 g/L of Mn- and/or Zn ions, of which at least one type of these ions in the content range of 0.01 to 1 g/L is present,

[0063] 0 or 0.01 to 0.3 g/L of Fe2+- ions,

[0064] preferably Mn- and/or Zn ions are present,

[0065] 0 or 0.01 to 1 g/L of organic polymer and/or organic copolymer, which is stable at a pH value < 6.5, with respect to solid matter content,

[0066] 0 or 0.01 to 1 g/L of particulate SiO2 with an average particle diameter < 0.3 μm, measured in a scanning electron microscope and with respect to solid matter content,

[0067] about 0 or 0.01 to 6 g/L of at least one surfactant,

[0068] about 0 or 0.05 to 6 g/L of anions selected from the group consisting of carbonate, nitrate and sulfate, converted to NO3+, even though CO32+ or SO42+ are present and

[0069] 0 or 0.001 to 1 g/L of carboxylate and/or sulfonate anions, which do not or almost do not impair the layer formation, calculated as the corresponding anions,

[0070] being that the content of molybdate calculated as MoO42+ and/or the content of oxyanions containing P calculated as PO43+ is respectively < 0.1 g/L or about 0 g/L and being that the aqueous composition presents a value of pH in the range of 2.5 to 6.5 and 4 preferably in the range of 3.0 to 5.5.

[0071] Especially preferably the acidic aqueous composition contains, is composed primarily of or is additionally composed of:

[0072] 0.1 to 5 g/L of the sum of lithium, sodium and/or potassium ions, 0 or 0.05 to 5 g/L of ammonium ions,

[0073] about 0 or 0.05 to 0.2 g/L of the sum of Co- and/or Ni Ions, respectively 0 or 0.01 to 0.4 g/L of chlorate calculated as CIO3", calculated nitrite as NO2 and/or peroxide calculated as H2O2,

[0074] 0 or 0.01 to 0.5 g/L free fluoride calculated as F- and

[0075] 0 or 0.01 to 0.1 g/L of vanadate ions calculated as VO43". In this case, the bath composition according to the invention can preferably be made by diluting one or two concentrates with water in a dilution factor in the range of 5 : 1 to 40 : 1. The second concentrate could, for example, contain at least one surfactant and also be aqueous. form of the corresponding acids The free fluoride content is often in the range of 0.01 to 0.2 g/L.

[0076] Preferably, the aqueous acid conversion composition is worked with tap water with a conductance value of, for example, about 200 to 600 S/cm or with totally desalted water, although for the preparation as well as for the addition of the liquid level in the bath, as well as for the first wash after the conversion coating.

[0077] After this first washing step, a washing with fully desalted water according to the specifications is necessary only as a conclusive wash in order to prevent a drying of the salt load which can allow a worse corrosion protection.

[0078] On hot dip galvanized (HDG) sheet metal, paint adhesion and corrosion protection are less favorable than on cold galvanized steel (CRS) sheet metal. When the zinc content in the acidic aqueous conversion composition is decreased or avoided altogether, the coating properties on hot-dip galvanized steel sheet are often improved.

[0079] A content of Fe2+- ions often does not worsen the coating properties, but it is found that Fe2+- ions are gradually oxidized to form Fe3+ and deposited as bath sludge. For this reason it is preferred that the aqueous acid conversion composition has a content of manganese and/or zinc ions.

[0080] An aqueous surfactant-containing composition can help to further improve after degreasing and/or after corrosive attack cleaning or at least dispense with a degreasing prior to conversion coating so that in a one-pot process the cleaning and so that the cleaning stage is suppressed and is done within the scope of the conversion coating.

[0081] In the case of the method according to the invention it is preferred that at least one substrate is placed in contact with metallic surfaces with aqueous composition in the range of 1 second to 10 minutes, especially from 0.5 to 10 minutes during the treatment of parts. Especially preferably in this case it is contacted in the time range of 1 to 10 minutes especially during immersion or preferably from 0.5 to 6 minutes especially during washing. Thus, even in the case of these compositions, the same treatment times are used as in alkaline phosphatization, which facilitates the adjustment of alkaline phosphatization installations for a coating according to the invention. So in the case of alkaline phosphatization, 3 to 5 minutes are often used. Alternatively, the composition according to the invention can also be applied in a spiral if after the spiral coating it has not yet been washed with water (rinsing process). In the case of spiral coating coating the metal strip is contacted with the aqueous composition preferably for a period of time in the range of 1 second to 2 minutes.

[0082] In the case of the method according to the invention, it is preferred that the substrate with metallic surfaces in contact with the aqueous composition has a temperature in the range of 5 to 90 °C and preferably in the range of 15 to 70 °C or 30 to 30 °C. 60°C. On the other hand, it is also preferred that an aqueous composition in contact with the substrate with metallic surfaces has a temperature in the range of 35 to 70°C or 45 to 60°C. With this, also in these compositions, the same temperatures as in alkaline phosphatization, in which 50 to 55 °C is often used, can be used. In the case of a temperature in the range of 50 to 55 °C, the most uniform possible conversion coatings are obtained and even after application of painting, the most uniform layers of paint possible.

[0083] The task is also solved with a substrate coated with metallic surfaces, which has been coated according to the invention.

[0084] In this case, it is preferred that the coating generated here presents a layer thickness of 0.3 to 3 μm and/or that the sum of the measured elemental zirconium and/or titanium support when the conversion coating is located in the range from 1 to 300 mg/m2 or preferably in the range from 15 to 150 mg/m2 , measured with an X-ray fluorescence (RFA) instrument.

[0085] In this case, it is also preferred that the coating generated here be colored, iridescent or gray. Preferably, in the case of the coating generated here, 1st or higher order interference colors occur in colors in which the interference color overlaps with the ion color. These colors are similar or similar as in the case of an alkaline phosphate coating. Colors often help to analyze the thickness and partially also the uniformity and/or quality of an approximate coating. If this is possible even at longer viewing distances, it is especially advantageous in the case of a coating method.

[0086] Especially for application purposes, it is especially preferred that the conversion coating according to the invention generated here is then washed with water or with an aqueous backwash solution, especially with a content of silane, organic polymer and/or of organic copolymer and eventually also receives paint application. After washing can be done with after washing solutions such as Gardolene® D95 with a phenolic resin content or with silane based Gardolene® D6890.

[0087] Especially preferably the afterwash solution contains a content of respectively at least one a) cation selected from alkaline earth metal, aluminum, titanium, yttrium and heavy metal ions, b) organic polymer and/or organic copolymer, c) silane, silanol, siloxane and/or polysiloxane and/or d) complexing fluoride wherein complexing fluoride also represents the corresponding fluorine-containing acid. As silane, in this case, especially aminosilane with one, two or even more amino groups and/or Bis-silyl-silane are preferred.

[0088] In the case of an especially preferred method according to the invention, a coating is applied with an aqueous acidic composition according to the invention, optionally then washed with water and/or optionally then washed with an aqueous composition and at least at least one coating manufactured in this way is then painted at least once.

[0089] In this case, for a method according to the invention especially preferred with an aqueous acidic composition according to the invention based on 0.01 to 1 g/l of TiF62+, ZrF62+ and/or HfF62+ or only of ZrF62+ in the form of ions calculated as ZrF62+ and 0 or 0.01 to 1 g/L respectively of Fe2+-, Mn- and/or Zn ions, of which at least one type of these ions lies in the content range of 0.01 to 1 g/L, as well as optionally 0.01 to 2 g/L of particulate SiO2 with an average particle diameter < 0.3 μm, in relation to the solid matter content and/or optionally 0.01 to 10 g/ L of at least one surfactant, which is basically phosphate-free and basically phosphonate-free, a coating can be applied, optionally then washed with water and/or optionally then washed with an aqueous composition based on fluoride complexing agent. zirconium, silane and/or organic polymer/organic copolymer, which is stable at a pH value < 6.5, and at least one coating so manufactures do can be REM then painted at least once. Due to the content of surfactant in the aqueous acidic composition according to the invention, it is possible, if necessary, to dispense with a previous cleaning stage.

[0090] The conversion coating generated herein according to the invention may, if it contains no organic polymer and no organic copolymer, preferably may be dried without backwashing with water or preferably with an aqueous afterwashing solution having a silane, organic polymer and/or an organic copolymer and optionally also painted.

[0091] The conversion coating according to the invention produced herein may alternatively be used if it contains organic polymer and/or copolymer, preferably without a coating with a primer, paint coat or adhesive.

[0092] The conversion coating according to the invention produced herein may be coated after at least one wash with water and/or an aqueous after-wash solution preferably at least once with a primer, primer or adhesive. Thus, the same treatment steps, treatment sequences and treatment methods can also be used in the case of such compositions if necessary as in alkaline phosphatization successfully.

[0093] The coating generated here may surprisingly represent a replacement for an alkaline phosphate coating, for example, for an iron phosphate coating.

[0094] At least one substrate with metallic surfaces, which has been coated according to the invention, is preferably used as an architectural element, as a container, as a construction or joining element, as a profile element, as a heating element element , as a complicated molded part and/or as a component in the field of building construction, energy technology, automotive construction, equipment construction, household appliance construction or machine construction.

[0095] It was surprising that with the aqueous conversion compositions according to the invention excellent coatings were produced, which show extraordinary corrosion resistance, excellent paint adhesion and to a large extent also a defined color. Corrosion resistance on steel surfaces is in this case almost as good as that of a high-quality zinc phosphatization and therefore far superior to the corrosion resistance of a high-quality alkaline phosphatization without a wash solution having been used. later to improve the coating properties. By using an additional after-cleaning solution, it is even possible to obtain the corrosion resistance of high-quality zinc phosphating.

[0096] It was also surprising that in a relatively simple way a very active substitution was possible, produced in a simple method, compatible with the environment and eventually absolutely identical, in relation to an alkaline phosphatization.

[0097] The composition according to the invention and the method according to the invention are especially advantageous in the case of chemical pretreatment of surfaces composed of different steel substrates which are applied in the metal processing industry. In this case, cleaning can be carried out even in one working step and at the same time a paintable conversion layer can be applied, for this purpose this three-stage treatment method consists of cleaning with conversion coating, washing with water and washing with water completely. desalted is enough. Above all, bath analytics can be handled very simply as an accurate determination of anions and cations is only very rarely necessary since the pH value and conductivity provide information as to the chemical bath state.

[0098] The method according to the invention can be used for the manufacture of a colored, iridescent, gray or colorless (as in B40) passivation layer (without applying a coat of paint) or a colored, iridescent conversion coating , gray or colorless (as in B40) (with primer coat). A passivation layer itself is also a coating manufactured by conversion. For this reason, the term "conversion coating" implies in the sense of this patent application also the term "passivation layer", insofar as or if no coat of paint is applied, for example, including in the claims.

[0099] The method according to the invention can be employed as a replacement for an alkaline phosphatization method or separately even as a replacement for a zinc phosphatization method. The products manufactured according to the invention can be used in a variety of ways, especially as an architectural element, as a container, as a construction or joining element, as a profile element, as a heating element element, as a complicated molded part and/or or as a component in building construction, energy technology, automotive engineering, appliance construction, household appliance construction or machine construction and for example as a heating element, as a frame, as plates, as cladding, as corners or as components in the field automotive or aircraft interior. Examples and Comparative Examples:

[00100] The object of the invention is clarified in more detail on the basis of the embodiment examples. The examples were carried out using the substrates listed below, process steps, substances and mixtures.

[00101] Gardobond® C standard sheets made of cold rolled steel, CRS, of St14 DC05, Gardobond® HDG/5 made of corresponding hot-dip galvanized steel or Gardobond® F of AA 5005 of AlMgl manufactured by Chemetall GmbH were used for the coating. If there is no indication to the contrary, standard Gardobond® C plates were used.

[00102] Aqueous conversion compositions corresponding to table 1 were prepared. A non-ionic surfactant from Gardobond® Additiv H7438 was used as surfactant, which allows an additional cleaning of the metallic surface. The SiO2 alkaline dispersion stabilized with Gardobond®Additiv H 7157 potassium hydroxide from Chemetall GmbH had a solids content of 20% as well as an average particle size of 0.2 µm. The polymer dispersion 1 AC 2773 based on Alberdingk's acrylate had a solids content of 53%. The 2 VA 294 VP acrylate content copolymer dispersion from Alberdingk had a solids content of 47%. The copolymer dispersion containing 3 AS 2084 VP acrylate from Alberdingk had a solids content of 53%. Organic polymer, organic copolymer, SiO 2 - particle and/or surfactant were added to the previously prepared aqueous conversion composition separately at the end of the mixing process. In individual tests ammonium molybdate was added.

[00103] In examples B45 to B48, a content of about 0.02 g/L of Fe2+ had already been incorporated in the bath due to the corrosive effect of the acid conversion composition. This iron content removed is therefore higher than in other tests which was < 0.001 to 0.01 g/L Fe2+ in the bath. In compositions B41 and B42, the iron content mentioned in the table was intentionally added.

[00104] Metal sheets were conversion coated at 55 °C for 3 minutes with cleaning effect when active surfactant was present. It was then washed once with operating water and then with VE water, before the coated metal sheets were dried at 120 °C in the drying oven for at least 10 minutes. When using another temperature, no marked difference in quality was observed.

[00105] A coat of paint was then applied respectively to the conversion coated sheet metal: either an Interpon® 700 epoxy powder lacquer from Akzo Nobel Powder Coatings GmbH in a layer thickness of 60 to 80 μm, a lacquer Alexit® Monolayer based on polyurethane and Mankiewicz isocyanate in a layer thickness of 60 to 80 μm or a BASF Cathoguard® 350 black cathode clearcoat in a layer thickness of 15 to 20 μm in example B3 or in examples B45 to B48 a BASF Cathoguard® 800 (KTL) cathode varnish in a layer thickness of 15 to 20 μm and then respectively a layer of an automotive frame by Daimler Benz of 25-30 μm of arga, 11 -15 μm of lacquer base and 40-50 μm of varnish.

[00106] The lacquer adhesion of the varnished samples was determined using the grid-cut method according to DIN EN ISO 2409 before or after a 240 h test of changing climatic conditions. The corrosion resistance of the varnished samples was determined in the salt spray test according to DIN 50021 for 500 hours in the NSS neutral salt spray test. In this case, unlike what happens in the Asian and North American market, only a single layer of varnish was applied.

[00107] Surprisingly, in the salt spray test after 1000 h with 0 mm B44, extraordinary corrosion resistance was also obtained.

[00108] The layer weight was measured in mg/m2 for an elemental zirconium layer measured with the X-ray fluorescence equipment. The zirconium element is often the conductive element of the coating quality and according to each metallic substrate with the same aqueous composition different metallic layers are separated in zirconium.

*Azul desigual

[00109] The examples according to the invention were compared in the case of the comparative examples VB1 and VB2 with an internationally widely used high quality alkaline phosphatization in Gardobond® C metal sheets made of cold rolled steel: in this case the typical process cycle when alkaline phosphating, which is also called when using iron and steel materials iron phosphating, was operated with Gardobond® WH = Gardobond® A 4976 on steel surfaces at 55 °C for 3 minutes, when washing with VE water and, if necessary, after washing for 5 minutes with a ZrF6-based Gardolene®D 6800/6 after washing solution, before drying at 120 °C in the drying oven for at least 10 minutes. Alternatively, it was operated with a Gardolene® D 6890 after washing solution based on aminosilane with surfactant, with an Oxsilan® 9810/3 after washing solution based on two aminosilanes of different types and ZrF6 or with a washing solution of an acrylate-based polymeric dispersion 1 AC 2773, before and having been dried at 120 °C in the drying oven for at least 10 minutes. Table 1: Overview of the compositions of the aqueous baths and the properties of the respective coated samples and coatings

*Uneven blue

[00110] The examples show that with the aqueous conversion compositions according to the invention, despite the compositions that are often very simple and of minimal contents, extraordinary coatings have been obtained which have extraordinary corrosion resistance under these conditions, an extraordinary lacquer adhesion. -naria and largely also a defined color. With these compositions, both strongly dyed and colorless coatings can be produced. Corrosion resistance on steel surfaces is nearly as good as a high quality zinc phosphatization and therefore far superior to the corrosion resistance of a high quality alkaline phosphatization (eg B3 compared to VB1).

[00111] In the case of the comparative example VB2, the coating properties were determined only after a second additional conversion treatment - unlike what happened in the examples according to the invention. Lacquer adhesion on steel surfaces is even as good as a high quality zinc phosphatization and therefore far superior to the lacquer adhesion of a high quality alkaline phosphatization. In addition, the aqueous conversion compositions according to the invention are composed in an environmentally compatible way, advantageous with regard to working hygiene and free from phosphate.

[00112] When a backwash solution, for example with a silane, organic polymer and/or organic copolymer content was used after conversion coating according to the invention and after at least one water wash, it obtained lacquer adhesion is obtained on steel surfaces which is at least as good as with a high quality zinc phosphatization and corrosion resistance which is at least as good as with a zinc phosphatization is also obtained.

[00113] In short, it has been found that the acidic aqueous conversion compositions according to the invention are extraordinarily suitable for replacing alkaline phosphatization on different metal substrate surfaces of different types and not only for iron phosphatization on metal substrate surfaces. iron and Steel. In this case even a multiple metallic capacity was obtained during the treatment so that at the same time or successively a mixture of metallic surfaces of different types can be treated in the same bath.

[00114] When exchanging ZrF6 for TiF6, you can have minimal damage, especially on steel, compared to the improved layer properties in corrosion protection.

[00115] In the case of using only zinc as the added heavy metal cation, high quality coatings were obtained, even though the zinc content of the coatings remained unexpectedly remarkably low and when no phosphate was added. Using only manganese as the heavy metal cation resulted in high quality coatings, although the manganese content of the coatings also unexpectedly remained very low and when no phosphate was added. When manganese and zinc were added at the same time, minimal damage was obtained with respect to only one of these heavy metal cations when no phosphate was added.

[00116] Using only Fe2+ as a heavy metal cation or additionally Mn and/or Zn ions, high quality coatings were also obtained. In this case Fe2+ was supplied and subsequently extracted from the substrate by the corrosion process conditioned to the bath reaction of iron-containing substrate surfaces. This was oxidized, but many times by stirring in a bath forming Fe3+ and removed from the bath as a reactive component. Despite the addition of Fe2+ an adjustment was made many times to a stationary Fe2+- concentration in the range of 0.025 to 0.1 g/L of Fe2+ , as also in examples B41 and B42.

[00117] As in the case of longer lasting coatings, for example with a plurality of substrates the main elements and a part of the alloying elements in the aqueous acid conversion composition have been removed by corrosion and may partially accumulate in the bath composition , several cations are often present in the bath simultaneously, which can interfere with the composition of the coating and, consequently, its properties.

[00118] If no heavy metal cations were added as in the case of comparative examples VB3 and VB4, largely worse coatings were obtained. Zn and Mn are separated in contrast to Zr, only in amounts irrelevantly measurable with respect to measurements with X-ray fluorescence analysis. Zr is, however, the main component of the layer and can be present, for example, as (Zr(OH )xFy). Zn acts in the boundary area of the metallic coating many times as a fluoride scavenger, in which less fluorine can be incorporated into the layer, which produces better results in the depositor's understanding. Zn and Mn are only in minute amounts a component of the layer and can therefore be more accurately verified by means of XPS/ESCA photoelectron spectroscopy.

[00119] The generated properties of the coatings are often the best when the Zr layer in comparative tests is the largest. However, the Zr layer - on different steel units and even on the same steel units differs in terms of surface properties.

[00120] In the tests, a non-ionic surfactant was also added, which further improved the cleanliness of the metallic surface of the standard metal sheets used made of CRS Gardobond® C. Therefore, it was possible to dispense with a preliminary cleaning stage. When, in comparison, it was possible to dispense with the addition of surfactant, no other properties of the coating were obtained at first, except that the metallic surfaces were not cleaned satisfactorily, which could negatively interfere with the layer properties. .

[00121] In the case of higher molybdate additions, pay attention to the possibility of a slight detachment of the coating.

[00122] Additions of organic polymer, organic copolymer and SiO2- nanoparticles proved especially suitable. In this case, attention should be paid to the fact that in addition amounts above 0.5 g/L, there are no foaming disorders, incrustations and lateral thickening.

Claims (15)

1. Method of coating metal surfaces with an aqueous acid conversion composition, which is a solution or dispersion characterized by containing: a total content of 0.01 to 1 g/L of TiF62-, ZrF62- and/or HfF62 -, in the form of ions, calculated as ZrF62-; 0 or 0.01 to 1 g/L, respectively, of Fe2+, Mn and/or Zn ions, of which at least one type of these ions is present in the content range of 0.01 to 1 g/L, 0.01 to 2 g/L of an organic polymer and/or an organic copolymer based on (meth)acrylate/(meth)acrylic acid and/or vinyl acetate-acrylic copolymer, which are stable at pH <6.5 , with respect to solids content, 0 or 0.01 to 2 g/L of SiO2 in particles with an average particle diameter <0.3 μm, with respect to solids content, 0 or 0.01 to 10 g/ L of at least one surfactant, 0 or 0.05 to 10 g/L of anions selected from the group consisting of carbonate, nitrate and sulfate, converted to NO3-, even though CO32- or SO42- is present, and 0 or 0.001 to 2 g/L of carboxylate and/or sulfonate anions, which cause little or no deterioration in the layer formation process, calculated as the corresponding anions, where the molybdate content, calculated as MoO42+ and/or the content of oxyanions containing P , calculated as PO43-, is <0.1 g/L or 0 g/L, and the acidic aqueous composition has a pH in the range of 2.5 to 6.5, wherein no content of silane, silanol, siloxane and/or polysiloxane is intentionally added to the aqueous conversion composition. Method according to claim 1, characterized in that the acidic aqueous composition additionally contains: 0.03 to 5 g/L of the sum of lithium, sodium and/or potassium ions, 0 or 0.05 to 5 g/L of ammonium ions, about 0 or 0.05 to 0.3 g/L of the sum of Co and/or Ni ions, respectively 0 or 0.01 to 0.8 g/L of chlorate calculated as CIO3- , Nitrite calculated as NO2 and/or a peroxide calculated as H2O2, 0 or 0.01 to 0.5 g/L free fluoride calculated as F- and 0 or 0.01 to 0.2 g/L vanadate ions calculated as VO43-. Method according to at least one of the preceding claims, characterized in that the coating produced here has a layer thickness of 0.3 to 3 μm. Method according to any one of the preceding claims, characterized in that the sum of the measured elemental zirconium and/or titanium layer is in the range from 1 to 300 mg/m2, measured with an X-ray fluorescence equipment. Method according to at least one of the preceding claims, characterized in that the coating generated here is colored, iridescent or grey. Method according to at least one of the preceding claims, characterized in that the coating produced here represents a replacement for an alkaline phosphate coating. Method according to at least one of the preceding claims, characterized in that the bath composition is produced by diluting one or two concentrates with water at a dilution factor ranging from 5:1 to 40:1. Method according to at least one of the preceding claims, characterized in that at least one substrate with metallic surfaces is placed in contact with an aqueous composition for a period ranging from 1 second to 10 minutes. Method according to at least one of the preceding claims, characterized in that the substrate with metallic surfaces, when in contact with the aqueous composition, has a temperature in the range of 5 to 90°C. 10. Method according to at least one of the preceding claims, characterized in that an aqueous composition, when in contact with the substrate with metallic surfaces, has a temperature in the range of 35 to 70 °C. 11. Method according to at least one of the preceding claims, characterized in that before the substrate is placed in contact with the aqueous composition, cleaning is carried out. Method according to at least one of the preceding claims, characterized in that the aqueous composition also contains at least one surfactant and that the cleaning and conversion coating are carried out in the same process step. Method according to at least one of the preceding claims, characterized in that the conversion coating produced here is then washed with water or with a post-wash solution, especially with a content of silane, organic polymer and/or a organic copolymer and optionally also lacquered. Method according to at least one of the preceding claims, characterized in that the conversion coating produced here is washed with water or an aqueous afterwash solution, wherein the afterwash aqueous solution contains at least one of each: a) cation selected from alkaline earth metal, aluminum, titanium, yttrium and heavy metal cations, b) an organic polymer and/or an organic copolymer, c) silane, silanol, siloxane and/or polysiloxane and/or or d) complex fluorine. Method according to at least one of the preceding claims, characterized in that the conversion coating produced here is coated, after at least one wash with water and/or an aqueous post-wash solution, at least once with primer, lacquer or adhesive substance.