EP2255025A1

EP2255025A1 - Process for coating metallic surfaces with a passivating agent, the passivating agent and its use

Info

Publication number: EP2255025A1
Application number: EP09719612A
Authority: EP
Inventors: Mark Andre Schneider; Petra Grünberg
Original assignee: Chemetall GmbH
Current assignee: Chemetall GmbH
Priority date: 2008-03-11
Filing date: 2009-03-10
Publication date: 2010-12-01
Anticipated expiration: 2029-03-10
Also published as: PL2255025T3; CA2718242A1; EP2255025B2; CN102027157A; JP5562261B2; ES2547119T3; AU2009224757A1; CA2718242C; CN102027157B; MX2010009941A; ES2547119T5; AU2009224757B2; WO2009112480A1; US20110008645A1; DE102008000600A1; DE102008000600B4; US20170314137A1; EP2255025B1; JP2011517727A; PL2255025T5

Abstract

The invention relates to a process for coating metallic surfaces with an aqueous composition as solution or as dispersion, wherein the composition contains at least one phosphate, at least 3 g/l of at least one titanium or/and zirconium compound and at least one complexing agent, and also corresponding aqueous compositions. The coatings produced therewith display very good bare corrosion protection in the NSS salt spray test and in the condensate water constant temperature and humidity test.

Description

Process for coating metallic surfaces with a passivating agent, the passivating agent and its use

The invention relates to a process for the coating of metallic surfaces with an aqueous composition which differs from phosphatizing solutions, the aqueous composition and the use of the process according to the invention.

Phosphate coatings are used on a large scale as corrosion protection layers, as a forming aid and as a primer for paints and other coatings. Especially if it is used as protection for a limited time, in particular storage and then, for example. are painted, they are referred to as a pretreatment layer before painting. However, if the phosphate coating is not followed by a lacquer coating and organic coating, treatment or passivation rather than pretreatment is used. These coatings are also referred to as conversion layers if at least one cation of the metallic surface, ie the surface of the metal part, is dissolved out and used for layer construction.

Among the coating methods, the so-called "no-rinse processes" are of great importance, in particular for the very rapid coating of continuously running tapes of at least one metallic material. These bands may be sheets of small or very large width. On these tapes, a phosphate coating is applied by wetting with a phosphating solution usually directly after galvanizing, but optionally also after suitable cleaning or degreasing and after rinsing with water or an aqueous medium and optionally after activation of the metallic surface and dried. Rinsing after drying of the phosphate coating could adversely affect this, especially if the phosphate coating is not or only partially crystalline. In the past, these problems were largely avoided by adding nickel to the phosphating solution so that it usually contained nickel contents in the range from 0.5 to 1.5 g / l. For zinc-manganese-nickel-phosphating, zinc contents in the range of 0.6 to 3.5 g / l and manganese contents in the range of 0.4 to 2.5 g / l were usually selected.

However, the high-grade phosphating solutions and phosphate coatings contain a significant amount of zinc, manganese and nickel. In particular, nickel is to be avoided because of its toxicity and harmfulness. In addition, the unavoidable heavy metal contents in the waste water, in the phosphate sludge and in the grinding dust are disturbing. For the treatment of tapes, however, there are no methods available that ensure a high level of blank corrosion protection (corrosion protection without lacquer / primer layers), especially for zinc-rich metallic surfaces.

DE 102006052919 A1 teaches aqueous compositions for the corrosion-protective conversion treatment of metallic surfaces based on 5-50 g / L phosphate, 0.3-3 g / L zinc and 0.001-0.2 g / L of titanium or / and zirconium in water-soluble titanium / zirconium compounds.

Despite the comparatively high phosphate content, the compositions of the present application are not phosphating solutions and the coating process is not phosphating since a phosphating solution:

1. for high quality phosphate coatings e.g. in zinc or / and manganese-rich phosphating processes, prior activation e.g. based on titanium phosphate particles or zinc phosphate particles needed, so that then a high-quality phosphate layer can be formed,

2. as a rule can only be used in zinc-containing phosphations in a pH range of 2 to 3.5, 3. usually can not tolerate any content of titanium and / or zirconium compounds of more than 0.05 or more than 0.1 g / l in total without disturbances, since titanium and zirconium compounds are known as bath poisons for phosphating,

4. in practice never contains a substantial content of silanes / silanols / siloxanes / polysiloxanes,

5. rarely contains a low content of a complexing agent, because this is sometimes considered a bad poison,

6. usually contains in bath solutions a total content of cations in the range of 3.5 to 9.5 g / L and of phosphorus-containing compounds in the range of 5 to 20 g / L calculated as PO ₄ ,

7. often contains an increased content of alkali metal and ammonium compounds, the pH remaining in the range from 2.0 to 3.5 even at comparatively high contents of ammonium compounds,

8. if it contains at least one complex fluoride, normally only compounds based on boron or / and silicon complex fluoride,

9. in the phosphating of parts with a zinc or / and manganese-rich phosphating solution at least in the treatment of parts e.g. by dipping or / and spraying usually crystalline layers of often typical crystal forms are formed and

10. In blank corrosion protection, the crystalline zinc phosphated surfaces show a salt spray test on phosphatized, non-lacquered O surfaces of typically only up to two hours without rusting due to pores and lack of closure, while the coatings of the invention usually for at least two days without additional paint treatment in the salt spray test are stable, without that the coatings according to the invention are thicker than the comparable phosphated coatings.

If, in very rare cases in a phosphating process, a titanium o- and / or zirconium compound is used in a phosphating solution, the contents of these compounds are typically less than 0.2 g / L in total. Because it is known that higher contents of these compounds usually lead to coating defects especially on aluminum-rich surfaces. Very rarely, a complexing agent is added to a phosphating solution. If, in very rare cases, a silane is used in a phosphating solution in a phosphating process, the contents are very low. But a combination of these additives is never used in phosphating.

It has been found time and again that the behavior of the aqueous compositions according to the invention and the properties of their coatings are so different compared to phosphating solutions and their phosphate coatings that it is not possible to speak of phosphating in the aqueous compositions according to the invention and their coating methods. Nevertheless, the method according to the invention is a conversion coating method of the first type.

It was therefore the object of proposing a coating method with which the corrosion protection layer produced with an aqueous composition without coating with a lacquer / primer has good corrosion protection (= blank corrosion protection), in particular on a metallic strip. Because the coil (reel) is usually to be processed by the steel manufacturer in further processing operation without rust approaches. In addition, for some embodiments, good formability or / and also good alkali resistance in mild alkaline cleaning or / and during forming with alkaline emulsions is / are advantageous. Optionally, the coating should also possible after forming have a good corrosion protection and preferably also a good paint adhesion.

The object is achieved with a method for coating - in particular for passivation by coating - of metallic surfaces with an aqueous composition as a solution or as a dispersion, wherein the composition comprises at least one phosphate, at least 3 g / L of at least one titanium and / or Zirconium compound and at least one complexing agent and cations of aluminum, chromium (III) or / and zinc and / or at least one compound containing aluminum, chromium (III) or / and zinc and that a wet film of the aqueous composition on metallic tapes or Sheet metal is dried up.

Usually, the aqueous composition according to the invention will be a solution unless particles or / and an emulsion are added, as long as this solution is stable and does not tend to precipitate.

The term "additive" or "adding" in the context of this application means that at least one such substance or mixture is added.

The composition according to the invention and the method according to the invention are used in particular for passivating the metallic surface, but can also be used for pretreatment before a subsequent coating, for example with an organic coating and for other purposes. For the purposes of this patent application, passivation is understood to mean the coating of metallic surfaces, in which normally no subsequent organic coating is applied for permanent protection against corrosion. However, in some cases passivation does not preclude the subsequent application of at least one organic coating such as a primer or even a paint system and / or an adhesive. The aqueous composition according to the invention preferably contains cations of aluminum, chromium (III), iron, manganese or / and zinc or / and at least one compound containing aluminum, chromium (III), iron, manganese or / and zinc. The starting composition according to the invention, that is to say in particular the fresh concentrate and / or the fresh bath composition, but often also the supplementary solution which is added to the bath in use when needed, in particular in order to obtain the bath ready for use, preferably contains one in many embodiments essential content of cations and / or of at least one compound of aluminum, chromium (III), iron, manganese or / and zinc. In many embodiments, in addition to the cations and / or compounds of aluminum, chromium, iron, manganese, titanium, zinc and / or zirconium, it contains no or no substantial content of other heavy metal cations and / or heavy metal compounds in addition to those just mentioned. Often, it also contains no chromium content. However, in contact with the equipment, with the metallic surfaces to be coated or / and by entrainment of impurities, the composition can often take up further cations of and / or compounds. Therefore, the original chromium-free composition may also contain traces or occasionally even low contents, for example, of chromium and / or chromium compounds and / or cations / compounds from other steel refiners. The composition preferably contains a total content of cations of aluminum, chromium (III), iron, manganese or / and zinc or / and of at least one compound containing aluminum, chromium (III), iron, manganese or / and zinc in the range from 1 to 100 g / L calculated as metal. The composition preferably contains a total content of cations of aluminum, chromium (III) or / and zinc or / and of at least one compound containing aluminum, chromium (III) or / and zinc in the range from 1 to 100 g / L as metal. Very particular preference is given to the contents of aluminum, chromium (III), iron, manganese or / and zinc or of aluminum, chromium (III) or / and zinc in the range from 1.5 to 90, from 2 to 80, from 2 , 5-70, 3-60, 3.5-50, 4-40, 4.5-35, 5-30, 5.5-25, 6-20 or from 8 to 14 g / L, calculated as metal. Particularly preferred is a content of chromium (III) as cations and / or compounds zero, in about zero or in the range of 0.01 to 30, from 0.1 to 20, from 0.3 to 12, from 0, 5 to 8, from 0.8 to 6 or from 1 to 3 g / L calculated as metal. With particular preference the composition according to the invention with respect to the cations and / or the metal-containing compounds consists only of cations of aluminum, chromium (III) or / and zinc or / and of at least one compound containing aluminum, chromium (III) or / and Zinc. The content of chromium (VI) as cations and / or compounds may be in particular zero, about zero or in the range of 0.01 to 8, from 0.05 to 5, from 0.1 to 3 or from 0.3 to 1 g / L calculated as metal. Preferably, at least 60%, at least 80%, at least 90% or even at least 95% of these cations and compounds are those based on aluminum and / or zinc. The content of such cations and compounds can be varied widely. If appropriate, these can be complexed. It can also be considered that due to the pickling effect of the main constituent of the metallic surface such as zinc in galvanized surfaces, iron in steel surfaces and aluminum at aluminum surfaces with longer throughput is added at lower levels, because the main component of its own supplements due to the pickling. It is particularly preferred that the composition according to the invention contains essentially only cations of aluminum, titanium, zinc or / and zirconium or only these are added to the composition. It is particularly preferred that only cations and / or compounds of aluminum, chromium (III), titanium, zinc or / and zirconium are added to the composition according to the invention with respect to the cations and / or metal-containing compounds. It is very particularly preferred that the composition according to the invention contains only or essentially only titanium and zinc or titanium and aluminum or are added to the composition. It is particularly preferred that the inventive composition with respect to the cation and / or metal-containing compounds only cations and / or compounds of aluminum, chromium (III), titanium, zinc o- be added to the / and zirconium. Here, if appropriate, further types of cations, in particular trace impurities, introduced impurities or / and impurities thrown out of devices or / and substrates, may occur.

In most embodiments, the content of cations and / or at least one compound of alkaline earth metals is about zero or in the range of 0.001 to 1.5 g / L, from 0.003 to 1 g / L, of 0.01 to 0.5 g / L or from 0.03 to 0.1 g / L, calculated as the respective metal. If the content of these cations / compounds is very low, no disadvantages are to be expected. If the content of these cations / compounds is too high, the stability of the solution is endangered and losses in corrosion protection are to be expected. Alkaline earth metal levels usually interfere with precipitation. Fluoride (including complex fluoride) can easily precipitate with alkaline earth metal. In most embodiments, the content of cations and / or at least one compound of at least one alkali metal is about zero or in the range of 0.001 to 1.5, from 0.01 to 1, from 0.1 to 0.5, of 0.02 to 0.15 g / L, calculated as the respective metal. However, low alkali metal contents and alkaline earth metal contents often do not interfere when they are on the order of the levels of city water.

The aqueous composition of the present invention preferably has a content of phosphate in the range of 1 to 400 g / L calculated as PO ₄ . More preferably, the phosphate content of the composition ranges from 6 to 350, from 12 to 300, from 18 to 280, from 25 to 260, from 30 to 240, from 40 to 220, from 50 to 200, from 60 to 180, of 70 to 160, from 85 to 140 or from 100 to 120 g / L. If the content of phosphate is too low, the corrosion protection is low. Preferably, a phosphate additive is so high that a significant improvement of the corrosion protection and the surface appearance is obtained. If the phosphate content is too high, dull coatings may form. the. Preferably, the ratio of Al: PO ₄ in compositions whose content of cations and / or inorganic compounds selected from those based on aluminum, chromium, iron, manganese o- / and zinc predominantly comprises those based on aluminum, in Be Preferably, the ratio of Zn: PO ₄ in compositions whose content of cations and / or inorganic compounds is selected from those based on Aluminum, chromium, iron, manganese or / and zinc or based on aluminum, chromium or / and zinc predominantly on the basis of zinc, in the range from 1: 4 to 1:20, in particular in the range of 1: 6 to 1: 15. Preferably, phosphate is selected as at least one compound from monophosphates (= orthophosphates based on PO ₄ ^{3 "} , monohydrogen phosphates based on HPO ₄ ^2" , dihydrogen phosphates based on H ₂ PO ₄ ^" ), diphosphates , Tr iphosphates, phosphorus pentoxide and / or phosphoric acid (= orthophosphoric H ₃ PO ₄ ) added. A phosphate additive may be a monometal phosphate additive, an additive of phosphoric acid and metal, phosphoric acid and metal salt / metal oxide, diphosphate, triphosphate, polyphosphate or phosphorus pentoxide to water or to an aqueous mixture.

In the case of an addition, for example, of at least one orthophosphate, of at least one triphosphate or / and of phosphoric acid, a corresponding chemical equilibrium will be established, in particular in accordance with the pH and the concentrations of these additives. The more acidic the aqueous composition, the sooner the chemical equilibrium shifts to orthophosphoric acid H ₃ PO ₄ , and at higher pH values to tertiary phosphates based on PO ₄ ^{3 "} . For the purposes of this application, in principle many different orthophosphates can be added The orthophosphates of aluminum, chromium and / or zinc have proven to be particularly suitable, Preferably, at least one orthophosphate is added to the aqueous composition with an overall addition of .alpha Range of 1 to 400 g / L calculated as PO ₄ , more preferably in the range of 5 to 300, from 10 to 250, from 15 to 200, from 20 to 150, from 25 to 100, from 30 to 80 or from 40 to 60 g / L. The total addition corresponds to the total salary.

The aqueous composition may be prepared with phosphoric anhydride P2O5, with a phosphorus-containing acid, with at least one salt and / or ester of orthophosphoric acid and / or with at least one salt and / or ester of a condensed phosphoric acid, optionally together with at least one metal, carbonate , Oxide, hydroxide or / and salt such as Nitrate together with phosphoric acid.

The addition of at least one complexing agent may be advantageous and / or necessary if the pH is to be increased, when diluting the composition with water, when receiving levels of ions and / or compounds, in particular of other types of ions or / and other compounds or / and to stabilize the composition, in particular to prevent precipitation and / or dissolve. It serves to increase the content of compounds, in particular of cations such as aluminum, chromium, iron, manganese, zinc and / or of cations which are introduced, of being leached out of plants or / and of being leached out of the metallic surfaces, in US Pat Keep the composition dissolved. Because precipitations such as fluorides, oxides, hydroxides or / and phosphates in particular of aluminum, iron, manganese o- / and zinc can interfere because increasingly form sludge. If precipitation occurs, complexing agents can be added as needed to re-dissolve the precipitate. The at least one complexing agent serves in particular to complex cations such as aluminum, chromium, iron, magnesium, manganese, titanium, zinc and / or zirconium and thereby stabilize the solution or suspension, in particular at lower acidity. Moreover, in many embodiments, addition of at least one complexing agent has also been found to be more or less corrosive. protective of the ion. Upon re-addition of complexing agent (s) or / and at elevated levels of complexing agent (s) in the aqueous composition, it may be advantageous to also add at least one substantially neutral or basic compound to the composition in order to set a higher pH. The term "complexing agent" in the context of this application also includes chelating agents, in particular at least one compound based on alkoxide, based on carboxylic acid, based on phosphonic acid and / or on the basis of complexing organic compound, eg based on The higher the content of at least one complexing agent, the higher the pH of the composition can usually be adjusted as a function of the amount of cation The content of complexing agent The aqueous composition according to the invention preferably contains a total content of at least one complexing agent in the range from 1 to 200 g / L. More preferably, the total content of at least one complexing agent is in the range from 2 to 180, from 3 to 160, from 4 to 130, from 5 to 100, from 6 to 80, from 8 to 70, from 10 to 60, from 12 to 50, from 15 to 40 or from 20 to 30 g / L. Preferably, the complexing agent content is so high that the composition is a stable solution and that optionally stable solutions are obtained even when diluted with water. If the content of complexing agent is too low, depending on the amount of cation, an increase in pH or / and an increase in the contents of cations and / or compounds can lead to precipitation and thus possibly to precipitation and, if appropriate, to sludge formation. If the content of complexing agent is too high, the corrosion protection and / or the formability may be impaired.

In the process according to the invention, the aqueous composition may preferably contain at least one phosphonic acid, at least one salt of a phosphonic acid and / or at least one ester of a phosphonic acid be added. Preferably, the aqueous composition contains at least one phosphonic acid based compound in the range of from 1 to 200 g / L, more preferably in the range of from 0.3 to 150, from 1 to 80, from 1, 5 to 50 or from 2 up to 30 g / L. Particular preference is given to at least one compound based on phosphonic acid, for example diphosphonic acid, diphosphonic acid having an alkyl chain, for example 1-hydroxyethane-1,1-diphosphonic acid (HEDP), aminotris (methylenephosphonic acid) (ATMP), ethylenediaminetetra (methylenephosphonic acid ) (EDTMP), diethylenetriamine-penta (methylenephosphonic acid) (DTPMP), diethylenetriaminepenta (methylenephosphonic acid) (DTPMP), hexamethylenediamine-tetra) -methylphosphonic acid) (HDTMP), hydroxyethylamino-di (methylenephosphonic acid) ( HEMPA) or / and phosphonobutane-1,2,4-tricarboxylic acid (PBTC). These substances usually act as complexing agents.

In the method according to the invention, the composition preferably contains at least one carboxylic acid and / or its derivative: for example at least one compound based on formic acid, succinic acid, maleic acid, malonic acid, lactic acid, tartaric acid, citric acid or / and a chemically related hydroxycarboxylic acid or / and Aminocarboxylic acid including its derivatives. The at least one carboxylic acid can be complexing and / or anti-corrosive. Preferably, in some embodiments, the aqueous composition contains at least one carboxylic acid based compound in the range of from 0.1 to 100 g / L, more preferably in the range of from 0.3 to 80, from 1 to 60, of 1.5 to 45 or from 2 to 30 g / L.

Preferably, the composition according to the invention contains at least one compound based on phytin or / and tannin. These include, inter alia, compounds such as phytic acid, tannic acid and / or their derivatives such as their salts and their esters including their modified compounds and their derivatives. Compounds based on this chemical base can often have a particularly positive effect on corrosion protection. influence. They also act as complexing agents and are counted for the purposes of this application to the complexing agents. The composition in particular of the compounds based on tannin can vary considerably - for example, depending on the natural raw materials used - and their optionally carried out cleaning and / or chemical modification. They are partly colored. Preferably, the aqueous composition contains at least one compound based on phytin or / and tannin with a total content of these compounds in the range from 0.05 to 30 g / L, particularly preferably in the range from 0.3 to 25 g / L or from 1 to 20 g / L, most preferably in the range of 1, 5 to 15 g / L or from 2 to 10 g / L.

In the process of the invention, the aqueous composition preferably contains a total content of at least one titanium or zirconium compound of at least 5 g / L, 10 g / L, 15 g / L, 20 g / L or 25 g / L. In particular, this total content is in the range of 3 to 200 g / L. It is often present in a content in the range of 1 to 100 g / L of Ti or / and Zr calculated as metal. It may optionally be added partially or wholly as at least one complex fluoride or partly and wholly as at least one complex fluoride in the aqueous composition. More preferably, the aqueous composition contains a total content of at least one titanium or / and zirconium compound in the range of 1.5 to 200, 2 to 160, 3 to 130, 4 to 100, 5 to 80, 6 to 60 from 8 to 50, from 10 to 40 from 15 to 30 or from 20 to 25 g / L. More preferably, the content of Ti or / and Zr calculated as the metal in the aqueous composition is in the range of from 3 to 90, from 6 to 80, from 10 to 70, from 20 to 60, or from 35 to 50 g / L. As a titanium or / and zirconium compound, at least one compound which is usually stable only in the basic medium, but also with the addition of at least one complexing agent such as a phosphonate and / or at least one protective compound such as a surfactant, may also be added in the acidic medium is stable, said compound then being complexed or / and protected in the aqueous composition. More preferably, as the fluoride-containing compound, only at least one titanium-based compound and zirconium compound based on complex fluoride are added. In many embodiments, the composition contains at least one complex fluoride or / and its salt of aluminum, titanium, zinc or / and zirconium, which are present approximately as MeF ₄ or / and MeF ₆ complex. In particular with aluminum-containing metallic surfaces, not too low a complex fluoride addition is important in order to produce an increased pickling effect. More preferably, the aqueous composition contains at least one complex fluoride based titanium and / or zirconium compound in the range of from 1 to 200, from 1.5 to 175, from 2 to 150, from 3 to 120, from 4 to 100, from 5 to 80, from 6 to 60, from 8 to 50, from 10 to 40 from 15 to 30 or from 20 to 25 g / L. Preferably, the addition and content of at least one titanium or / and zirconium compound is so high that a good bare corrosion protection and, if necessary, a good paint adhesion to the subsequent paint / primer coating occurs. If the content of at least one titanium or / and zirconium compound is too high and if complexing agents are present in an insufficient amount, instability of the bath and hence precipitation can easily occur. Because a fluoride or a complex fluoride can also act as a complexing agent. However, fluoride and complex fluoride are not counted as complexing agents for the purposes of this application. The addition and content of a titanium compound has proved to be particularly advantageous for improving the corrosion protection. The addition and content of a zirconium compound has proved to be advantageous in particular in hot-dip galvanized surfaces for improving the paint adhesion. The titanium or / and zirconium compound according to the invention may in one embodiment be at least one corresponding complex fluoride and / or at least one complexed substance such as at least one titanium chelate, in particular at least one titanium alkoxide, the less reactive titanium and / or zirconium compounds are preferred. Vorzugswei- e is the weight ratio of silane / silanol / siloxane / polysiloxane to complex fluoride based on titanium or / and zirconium calculated as added silane or / and polysiloxane or optionally molar converted to H ₂ TiF ₆ less than 2: 1, less than 1, 5: 1, less than 1: 1 or less than 0.5: 1.

In certain embodiments, the composition of the invention contains at least one titanium or / and zirconium-containing fluoride-free compound, such as a chelate. This compound can serve to incorporate titanium or / and zirconium into the composition in a different form and is therefore a possibility of a source of such a compound. Such a compound can significantly improve the corrosion protection and stably keep the aqueous composition in solution. Preferably, the composition of the invention contains a content of titanium and / or zirconium chelates in the range of 0.1 to 200 g / L, more preferably in the range of 1 to 150, 3 to 110, 5 to 90, 7 to 70, 10 to 50 or 15 to 30 g / L. In particular, the content of such compounds is selected such that a content of titanium or / and zirconium in the range from 3 to 60 or 5 to 45 mg / m ² remains on the metallic surface, calculated as metal, determined by X-ray fluorescence. Such a compound is added in particular if no other titanium- or / and zirconium-containing compound is present in the composition according to the invention. Because it is particularly advantageous that at least one titanium or / and zirconium-containing compound is contained in the composition according to the invention. In particular, dihydroxo bis (ammonium lactate) titanate can be used as such a compound.

In the inventive method, the aqueous composition contains preferably approximately no fluoride content or a content of free fluoride F _freι in the range of 0.01 to 5 g / l and / or a content of total fluoride F _ges amt in the range from 3 to 200 g / L. Particularly preferably, the composition contains a content of free fluoride F _freι in the range of 0.1 to 3.5, 0.3 to 2 or from 0.5 to 1 g / L or / and a content of Total fluoride F _ge including the range of 3 to 180, 5-140, from 8 to 110, from 10 to 90, 12 to 75, from 15 to 60 or from 20 to 40 g / L. In many embodiments, no hydrofluoric acid, no monofluoride or / and no bifluoride is added to the composition of the invention. In that case, a content of hydrofluoric acid, monofluoride or / and bifluoride in the composition according to the invention can be formed in small amounts from at least one complex fluoride or / and its derivative only on the basis of the equilibrium conditions. In individual embodiments, the inventive composition hydrofluoric acid, monofluoride or / and bifluo hd is calculated with a total content of 0.01 to 8 g / L as free fluoride Ffrei, in particular from 0.1 to 5 or from 0.5 to 3 g / L added.

In the context of this invention, the term "silane" is also intended to include its hydrolysis, condensation, polymerization and reaction products, ie in particular silanols, siloxanes and optionally polysiloxanes The term "polysiloxane" should also include the condensation, polymerization and reaction products of Include polysiloxane.

In the process according to the invention, the composition in individual embodiments contains no content of at least one silane / silanol / siloxane / polysiloxane and in many embodiments preferably a content of at least one silane / silanol / siloxane / polysiloxane in the range from 0.1 to 200 g / L, calculated on the basis of silane or polysiloxane of the respective starting compound. It particularly preferably contains a content of at least one compound based on at least one silane / silanol / siloxane / polysiloxane in the range from 0.5 to 180, from 1 to 160, from 2 to 140, from 3 to 120, from 4 to 100 , from 5 to 90, from 6 to 80, from 8 to 70, from 10 to 60, from 12 to 50, from 15 to 40 or from 20 to 30 g / L, calculated respectively based on silane or polysiloxane of the respective starting compound. If the content of silane / silanol / siloxane / polysiloxane is too low, the corrosion protection of the coating deteriorates, in particular in hot-dip galvanized surfaces. If the content of Si lan / silanol / siloxane / polysiloxane is too high, it may lead to instability of the solution and thus to precipitation and / or incomplete wetting of the metallic surface. An addition of and content of at least one surfactant (wetting agent) can prevent problems at high levels, but also affect the corrosion protection of the coating produced. It has been found that a content of at least one surfactant can in some cases have a very strong influence on the properties of the coating according to the invention, in particular in corrosion protection. The corrosion protection can be significantly improved, in particular with less high quality grades of HDG. For this purpose, preferably at least one nonionic surfactant is added, optionally alternatively or additionally, at least one cationic surfactant. A second surfactant may optionally act as a solubilizer, in particular added as silane / silanol / siloxane or as polysiloxane, often improving the corrosion protection significantly. In particular, in most embodiments at least one silane is added, while at least one polysiloxane is added only in individual embodiments either alone or in addition to at least one silane.

The composition preferably contains at least one silane / silanol / siloxane / polysiloxane, in particular based on alkoxysilane, alkylsilane, amidosilane, aminosilane, bis-silyl-silane, epoxysilane, fluorosilane, imidosilane, iminosilane, isocyanatosilane, (meth) acrylatosilane or / and vinyl silane. Among these silanes / silanols / siloxanes / polysiloxanes, aminosilanes-based silanes / silanols / polysiloxanes have been found to be particularly useful, although the other silanes / silanols / siloxanes referred to herein may also be important depending on the embodiment. When adding silanes or / and derivatives thereof, which are optionally present after further condensation, in particular at slightly elevated pH, for example based on silanes / silanols / siloxanes having at least one nitrogen-containing group, eg of at least one amino group (= aminosilanes) , Amido group, imino group or / and imido group and / or under absorption protons with at least one ammonium group, these silanes / silanols / siloxanes contribute to an increase in the pH. Also, this may raise the pH, for example, from the original values in the range of 0.5 to 2 to values in the range of 1.5 to 4. Particular preference is given to a content of silanes / silanols / siloxanes having at least one nitrogen-containing group, for example of at least one amino group (= aminosilanes), amido group, imino group or / and imido group. The alkylsilanes may in particular be di-, tri- and / or tetrafunctional. In particular, the alkylsilanes may be without an organically functional side chain or, in particular, may have a terminal nitrogen-containing group. The alkylsilanes may optionally be without side chain, but may also have at least one side chain with a chain length of up to ten carbon atoms. Preferably, in some embodiments, the aqueous composition comprises each an addition of and content of at least one compound based on at least one silane / silanol / siloxane / polysiloxane a) having at least one nitrogen-containing group such as at least one amino group or ammonium group, b) based on of bis-silane (s), c) based on epoxysilane (s), d) based on fluorosilane (s), e) based on isocyanatosilane (s), f) based on (meth) acrylatosilane ( g) based on vinylsilane (s), h) based on alkoxysilanes or / and i) on the basis of alkylsilane, in each case in the range from 0.5 to 160 g / l, particularly preferably in the range from 1 to 120, from 2 to 80, from 3 to 50, from 5 to 35 or from 8 to 20 g / L. Particularly preferred silanes are 3-aminopropylthethoxysilane or / and 3-aminopropylthmethoxysilane (APS), N- [2- (aminoethyl)] - 3-aminopropyltrimethoxysilane (AEAPS), methylsilane, butylsilane, epoxysilane or / and tetraethoxysilane (TEOS) , For some silanes / silanols / siloxanes / polysiloxanes, higher levels of fluoride may cause the formation of HF gas.

Depending on the type and degree of polymerization, such as, for example, condensation, it is also possible to form siloxanes and / or polysiloxanes. Alternatively, it has been shown that the addition of and content of at least a polysiloxane or the addition of a combination based on silane and polysiloxane may be advantageous.

In the method according to the invention, the composition preferably contains at least one organic monomer / oligomer / polymer / copolymer. The term copolymer in the sense of this application also includes block copolymers and / or graft copolymers. The addition of and content of at least one such organic compound, preferably at least partially based on (meth) acrylic, epoxy, ethylene, polyester or / and urethane, is important in some embodiments to provide corrosion inhibitor, paint adhesion, formability to improve the friction and / or absorption of oil-containing contaminants from the oiled and / or soiled metallic surface. The latter is often used to avoid the cleaning of oiled and / or soiled metallic surfaces. Hereby, if appropriate, a small amount of tempering agent from a temper rolling process, a small amount of rustproofing oil of a coating for reasons of temporary rust protection or / and a small amount of forming oil from a forming process can be absorbed on a metallic surface coated according to the invention. The aqueous composition preferably contains at least one organic monomer / oligomer / polymer / copolymer in the range from 0.1 to 180 g / L, particularly preferably in the range from 2 to 120, from 5 to 80, from 8 to 55 or 12 to 30 g / L. Preferably, the content of organic monomer / oligomer / polymer / copolymer is so high that the formability is improved, in particular the friction is reduced during forming. Preferably, the content of organic monomer / oligomer / polymer / copolymer is so low that the stability of the aqueous composition is maintained and a good surface appearance of the coating is ensured, so that in particular no dull or / and streaky coatings arise. Preferably, the composition contains at least one organic monomer / oligomer / polymer / copolymer based on or / and containing (meth) acrylic, epoxy, ethylene, polyester or / and urethane. The at least one constituent mentioned here can also be at least one constituent of copolymer (s). Preferably, the aqueous composition contains a content of at least one organic monomer / oligomer / polymer / copolymer based on a) (meth) acrylic, b) epoxide, c) ethylene, d) polyester or / and e) urethane in the range of 0.5 to 80 g / L, more preferably in the range of 2 to 60, from 5 to 50, from 8 to 40 or from 15 to 30 g / L.

In the method according to the invention, the composition preferably contains in each case at least one inorganic or / and organic compound in particle form. In particular, organic particles may be present as a component of organic polymer / copolymer. Preferably, in some embodiments, the aqueous composition contains a content of inorganic and / or organic particles in the range of 0.05 to 80 g / L, particularly preferably in the range of 0.3 to 50, of 1 to 30, of 1, 5 to 15 or from 2 to 10 g / L.

The composition according to the invention preferably contains at least one inorganic compound in particle form based on Al 2 O 3, SiO 2,

TiO ₂ , ZnO, ZrO ₂ or / and corrosion protection particles having a mean particle diameter smaller than 300 nm measured under a scanning electron microscope. The inorganic particles such as those based on Al ₂ O ₃ , SiO ₂ , TiO ₂ or / and ZrO ₂ often also act as particles with a barrier effect and, if appropriate, with a connection to the metallic surface. In this case, ZnO particles, for example, can have a corrosion-protecting effect up to their possibly occurring dissolution. The corrosion protection particles may in particular be those based on, for example, silicate, especially alkali silicate or alkaline earth silicate, but also based on phosphates, phosphosilica, molybdates, etc. Corrosion protection particles can in particular Due to their barrier function and / or the release of ions, they help to protect against corrosion. Preferably, the content of inorganic particles is so low that no disturbing friction during forming occurs. Preferably, the content of inorganic particles is so high that the particles exert a barrier function and increased corrosion protection is achieved.

In certain embodiments, the composition according to the invention contains at least one accelerator, e.g. at least one accelerator selected from the group consisting of accelerators based on chlorate, nitrite, nitrobenzenesulfonate, nitroguanidine, perborate and at least one other nitroorganic compound with oxidizing properties which are known from phosphating. These compounds can also help to reduce or eliminate the formation of hydrogen gas at the interface with the metallic surface. In some embodiments, the aqueous composition contains at least one of these accelerators in the range of 0.05 to 30 g / L, more preferably in the range of 0.3 to 20, from 1 to 12, from 1, 5 to 8 or from 2 to 5 g / L.

Preferably, the composition according to the invention contains at least one additive, e.g. in each case at least one wetting agent, a demulsifier, an emulsifier, a defoamer, a corrosion inhibitor and / or a wax. If necessary, at least one additive can be added, as is customary and basically known in the case of conversion coatings, passivations or lacquers / primers. Preferably, the aqueous composition contains at least one additive having a total content of the additives in the range from 0.001 to 50 g / L, more preferably in the range from 0.01 to 30, from 0.1 to 10, from 0.5 to 6 or from 1 to 3 g / L.

The object is also achieved with an aqueous composition according to the main claim. The object is further achieved with a coating produced by the process according to the invention and / or with an aqueous composition according to the invention.

Preferably, the composition according to the invention contains: 1 to 100 g / L Al, Cr (III) or / and Zn together,

5 to 400 g / L phosphate as PO ₄ ,

1 to 200 g / L complexing agent,

1 to 100 g / L Ti or / and Zr calculated together as metal,

0.1 to 200 or approximately zero g / L F from at least one fluorine compound (Ftot) or / and

0.1 to 200 g / L of silicon compound (s) and optionally also at least one of the other compounds mentioned in this application.

Particularly preferably, the aqueous composition contains: 8 to 75 g / L Al, Cr (III) or / and Zn together,

40 to 280 g / L phosphate as PO ₄ , 20 to 120 g / L complexing agent,

3 to 60 g / l Ti or / and Zr calculated together as metal, 5 to 120 or approximately zero g / LF from at least one fluorine compound (F _{es officio} ) or / and

10 to 160 g / L of silicon compound (s) and, if appropriate, at least one of the other compounds mentioned in this application.

These figures apply to both concentrates and baths. In the case of baths, all of the above information on the areas can be divided by the dilution factor 4, for example.

Preferably, the weight ratio of (Al, Cr ³⁺ , Fe, Mn and Zn) is: (Ti and Zr) or / and of (Al, Cr ³⁺ and Zn): (Ti and Zr) in the range of 0.1: 1 to 3: 1. Particularly preferred are these weight ratios in the range of 0.5: 1 to 2.5: 1 or from 1: 1 to 2: 1.

In addition to the added contents, in particular of aluminum, chromium (III), iron, manganese, titanium, zinc or / and zirconium, these and, if appropriate, further cations may be present in the composition according to the invention. from previous baths, by impurities or / and by dissolving e.g. from tank and pipe materials as well as from the surfaces to be coated, on the other hand by adding further cations / compounds with a metal content such as e.g. at least one alkali metal, molybdenum or / and vanadium.

Preferably, in many embodiments, the aqueous composition of the present invention is free or substantially free of compounds based on carboxylic acid, acrylic acid, phenol, starch, chromium (VI) or / and based on other heavy metals, e.g. those based on chromium, molybdenum, nickel, vanadium or / and tungsten. In many embodiments, the aqueous composition according to the invention is preferably free or substantially free of compounds which are used as accelerators in the phosphating, in particular of compounds based on chlorate, nitrite, nitroguanidine, peroxide or / and other N-containing accelerators.

The compositions of the invention are preferably free or substantially free of chromium (VI). However, they may also be free or substantially free of chromium (III) in some of the compositions according to the invention, in particular then optionally free or substantially free of cations and / or compounds of chromium.

Preferably, the aqueous composition contains no or only a content of calcium or / and magnesium of not more than 0.5 g / L, particularly preferably not more than 0.15 g / L, or / and at least one A toxic or environmentally unfriendly heavy metal such as chromium of not more than 0.5 g / L, more preferably not more than 0.15 g / L. Fluoride-free compositions may also contain some or more calcium or / and magnesium.

The composition according to the invention preferably has a pH in the range from 0 to 10. In particular, the pH is in the range from 0.3 to 8, from 0.5 to 6, from 0.8 to 5, from 1 to 4 or from 2 to 3. Concentrates often have a pH value in the range of 0 , 3 to 3, baths often from 1, 5 to 4. The pH is often at the beginning of the work, at high concentrations or / and in non-truncated systems at values of 0.1 to 2, often in the range of 0 , 3 to 1. By dilution with water or / and by addition of certain basic substances such as ammonia, at least one amine compound (monoamines, diamines, thamins, tetramines, pentamines and others) or / and at least one polyamine compound (polymeric amine compound), at least one less acidic or substantially neutral silicon-containing compound or / and at least one organic polymer / copolymer, the pH in a range from 1 to 10, in particular from 1, 5 to 7, from 1, 8 to 5 or of 2 to 3.5 are raised, which is often beneficial. As a result, the composition itself is less corrosive. The at least one amine compound or / and at least one polyamine compound is in many cases also suitable as a pickling inhibitor. In principle, with an increased content of at least one complexing agent, a pH of the composition in the range from 2 to about 10 can be set, in which case an increased amount of at least one approximately neutral or / and basic compound is added. For influencing the pH, in particular ammonia, at least one other basic and optionally nitrogen-containing compound, at least one basic carbonate, hydroxide or / and oxide-containing compound, at least one organic polymer / copolymer or / and at least one silane / Silanol / siloxane / polysiloxane. For example, zinc oxide, manganese carbonate or / and substantially neutral or basic polymers or / and copolymers are added. The content of approximately neutral or / and basic agents which help to adjust the pH and added predominantly or only for the purpose of pH adjustment may preferably be zero or in the range of 0.05 to 100 g / L , more preferably in the range of 0.2 to 60, from 1 to 40, from 2 to 25, from 3 to 18 or from 4 to 12 g / L. Due to levels of fluoride or / and silane / polysiloxane, it may be advantageous not to measure with a glass electrode but to use pH indicator paper.

In the process according to the invention, the aqueous composition preferably has values of the free acid FS (FA) in the range from 2 to 25 points, values of the total acid GS (TA) in the range from 20 to 45 points or / and values of the total acid Fischer GSF ( TAF) in the range of 12 to 20 points. The acid value S for the ratio of FS: GS (FA: TA) is preferably in the range of 0.1 to 0.6. The acid value S for the ratio of FS: GSF (FA: TAF) is preferably in the range of 0.2 to 1.3. Particularly preferably, the values of the free acid FS (FA) are in the range of 6 to 16 points, values of the total acid GS (TA) in the range of 27 to 37 points or / and values of the total acid Fischer GSF (TAF) in the range of 15 to 18 points. More preferably, the acid value S for the ratio of FS: GS (FA: TA) is in the range of 0.2 to 0.5 or / and the acid value S for the ratio of FS: GSF (FA: TAF) is in the range of 0 , 35 to 1, 0. These values apply to titrations at concentrations of 60 g / L of solids and active substances, with the exception of ammonia levels.

An amount of 60 g of the aqueous composition to be analyzed is first made up to 1 liter with water and then diluted. To determine the free acid, 10 ml of the composition after dilution to 100 ml with deionized water (deionised water) using a Titroprocessor and an electrode with 0.1 M NaOH titrated to the inflection point. The consumed amount of 0.1 M NaOH per 10 ml of diluted composition gives the value of free acid (FS) in points.

The total content of phosphate ions is determined by titrating the titration solution to the 2nd inflection point after addition of potassium oxalate solution using a Titroprocessor and an electrode with 0.1 M NaOH following determination of the free acid. The consumption of 0.1 M NaOH for 10 ml of the diluted composition corresponds to Fischer's total acid (GSF). If this value is multiplied by 0.71, the total content of phosphate ions is calculated as P ₂ O ₅ (see W. Rausch: "The Phosphatization of Metals." Eugen G. Leuze-Verlag 1988, pp. 300 ff).

The so-called S value for the ratio FS: GS or FS: GSF is obtained by dividing the value of the free acid by the value of the total acid or total acid according to Fischer.

The total acid (GS) is the sum of the divalent cations present as well as free and bound phosphoric acids (the latter being phosphates). It is determined by the consumption of 0.1 molar sodium hydroxide solution using a Titroprozessors and an electrode. This consumption per 10 ml of the diluted composition corresponds to the total acid number.

Table 2 gives an overview of measurement results. These are formulations with the same starting composition, in which only the pH was varied with different amounts of ammonia.

Preferably, all or most of the compounds which are also contained in the solution in appropriate components are added as additives to the aqueous concentrate for the preparation of an aqueous composition. The composition of the bath is preferably by Dilute the aqueous concentrate with 10 to 1000% of the solids and active ingredient content of the concentrate made with water from the aqueous concentrate. But even a highly concentrated or / and undiluted solution or dispersion can be advantageously used in some embodiments.

All metallic materials can be coated with their metallic surfaces. Preferably metallic surfaces A- luminium, iron, copper, magnesium, titanium, zinc, tin and / or their alloys are coated, in particular zinc, steel, galvanized (hot dip gal vanized, HDG), electrolytically galvanized, Galvalume ^® - Galfan ^® - and / or AIu- si ^® surfaces. The composition according to the invention has proved to be outstanding, especially with zinc-rich or / and aluminum-rich metallic surfaces. For surfaces of iron and steel materials, in particular compositions having a pH in the range of 4 to 10, in particular of at least 5 or even of at least 7 have been recommended in order to avoid rapid rusting (flash rusting). The metallic components coated by the process according to the invention can be used in particular in vehicle construction, as architectural elements in the construction industry or for the production of devices and machines such as domestic appliances.

The coating produced according to the invention may have a widely varying coating composition. In particular, it may be characterized in that it contains: Al, Cr or / and Zn calculates as metal 1 to 100 mg / m ² , Ti or / and Zr together calculated as metal 1 to 100 mg / m ² ,

Si compound (s) calculated as metal 0.1 to 25 mg / m ² or / and P ₂ O ₅ 3 to 400 mg / m ² .

The coating according to the invention particularly preferably comprises: Al, Cr or / and Zn calculated as metal 10 to 70 mg / m ² , Ti or / and Zr calculated as metal 10 to 70 mg / m ² , Si compound (s) calculated as metal 1 to 15 mg / m ² or / and P ₂ O ₅ 80 to 220 mg / m ² .

These levels can be determined by X-ray fluorescence analysis on a trimmed coated sheet. Here, the weight ratio of (Al, Cr ⁰⁺ and Zn): (Ti and Zr) of the coating composition may preferably be in the range of 0.5: 1 to 1.8: 1, more preferably in the range of 0.9: 1 to 1, 4: 1.

The layer weight of the layer formed according to the invention can vary within wide limits. It may range from 0.01 to 12, from 0.05 to 10, from 0.1 to 8, from 0.3 to 6, from 0.5 to 4 or from 0.8 to 2 g / m ² , In the case of coating in strip systems, it can be in the range from 10 to 1000 mg / m ² , preferably in the range from 30 to 800 or from 60 to 650 mg / m ² , more preferably in the range from 100 to 500 or from 130 to 400 mg / m ² , very particularly preferably in the range from 160 to 300 or from 200 to 250 mg / m ² . The total content of titanium or / and zirconium in the dry film is preferably in the range of 1 to 100 mg / m ² of Ti or / and Zr calculated as metal, particularly preferably in the range of 10 to 60 mg / m ² . The total content of titanium or / and zirconium can be measured, for example, by X-ray fluorescence. The total content of silicon in the dry film when coated in strip lines is preferably in the range from 1 to 80 mg / m ² of Si calculated as metal, more preferably in the range of 3 to 40 mg / m ² . The total content of P ₂ O ₅ in the dry film is preferably in the range of 30 to 400 mg / m ² of P ₂ O ₅ , particularly preferably in the range of 60 to 300 mg / m ^2, when coated in strip lines.

The thickness of the coatings of the invention is often in the range of 0.01 to 5.0 microns, in particular in the range of 0.5 to 3.5, from 0.8 to 2.5 or from 1, 0 to 2 when coated in belt systems , 0 μm. When coated in strip lines, the thickness of the coating is often in the range of 0.01 to 1.2 microns, in particular in the range of 0.1 to 1, 0, from 0.2 to 0.8 or from 0.3 to 0.6 microns.

The aqueous compositions according to the invention frequently have a concentration of the solids and active substances (total concentration) in the range from 10 to 800 g / l. A concentrate may often have a total concentration in the range of 200 to 800 g / L, especially from 400 to 750 g / L. It can be diluted with water if necessary. The dilution of a concentrate is preferably carried out by a factor in the range of 1, 1 to 25, more preferably in the range of 1, 5 to 16, from 2 to 10 or from 3 to 6. The content of solids and active ingredients in the aqueous The composition depends above all on the type of substrate to be coated, on the particular installation and on the wet film thickness caused by the installation.

In many embodiments, the composition of the invention is used on metallic strip in coil coating processes. Many of the belt systems have a belt speed in the range of 10 to 200 m / min. The faster the belt is driven, the faster the reactions between the composition according to the invention and the metallic surface must take place so as not to require too long plant sections. The reaction time between application of the composition and its complete drying can take from a fraction of a second up to about 60 seconds. This may, in particular in the case of the faster belt systems, mean that the aqueous composition is too less reactive and therefore has to have a stronger acidity and a stronger pickling power. Preferably, its pH is in the range of 0.5 to 3.5 in coil coating processes. The concentration of all solids and active ingredients of the aqueous composition for coating in belt plants is often in the range of 200 to 800 or from 300 to 650 g / L. The contents of individual components or additives are adjusted according to the total contents. Usually, the aqueous composition is applied to the clean or cleaned metallic strip applied as a wet film by spraying and squeezing, which often has a wet film thickness in the range of 1 to 4 microns. Occasionally, a chemcoater or roller coater can be used instead.

In most cases, the wet film is dried on metallic strips or sheets (dry or no-rinse method). The drying can preferably take place in a temperature range from about room temperature to about 75 ^° C. peak metal temperature (PMT). The composition according to the invention can be aligned, for example, by means of suitable concentration and suitable pH, especially for a slow or rapid treatment in a belt system. Thus, neither the wet film, nor the dried film is rinsed with water, so that the ausgebeizten from the metallic surface cations and compounds are not removed, but are incorporated into the coating.

In the coating of metal parts according to the invention, such as sheet metal sections, castings, shaped articles and complicated shaped parts, the reaction time between the first contacting of the composition until its complete drying (no-rinse process) or until rinsing off the components which can be removed by rinsing with water (rinsing method) preferably take 0.5 to 10 minutes. Longer times are possible in principle. The concentration of all solids and active ingredients of the aqueous composition is often in the range of 10 to 300 or 30 to 200 g / L. In particular, in the case of rinsed coatings, it may sometimes be advisable to treat the coatings with a rinse-off solution, since a lot is often removed when rinsing with water. Instead of a layer formation, in some compositions it may also happen that in contact with the composition according to the invention substantially only a staining effect and / or only a very thin coating occurs, so that, for example, in hot-dip galvanized surfaces on zinc grain boundaries the zinc crystallization image is recognizable. This also illustrates the difference to a phosphating.

It was surprising that, in contrast to a phosphate layer, the coating according to the invention offers an unusually strong blank corrosion protection, even if the coating according to the invention is often much thinner than a phosphate layer and even if it is chromium-free. The blank corrosion protection of the coatings according to the invention is often better at least by the time factor 20 or 30 than with comparable zinc-phosphated coatings.

It was surprising that an increased content of ammonia in the composition according to the invention did not deteriorate the corrosion protection and is greatly improved by a content of silane, in particular on hot-dip galvanized surfaces.

It was surprising that the composition of the invention is an unusually stable solution at an increased content of complexing agent even at very high levels of solids and active ingredients.

Examples and Comparative Examples:

Examples (B) and comparative examples (VB) described below are intended to explain the subject matter of the invention in more detail.

Comparative Example VB 0:

Aqueous solutions were used to coat hot dip galvanized sheets in the laboratory roll coater containing only an addition of zinc dihydrogen phosphate (60%) in the range of 40 to 100 g / L and a corresponding molar amount of orthophosphoric acid in deionized water. There were coatings with a coating weight of about 110 to 360 mg / m ² P ₂ O ₅ . The coatings showed in neutral salt spray test (NSS test) according to DIN EN ISO 9227 (blank corrosion test) after about 1 hour Corrosion phenomena of 1 to 5 area% and already after 8 hours full, thick, white layers of zinc corrosion products. The condensate constant climate test according to DIN EN ISO 6270-2 (KK test) revealed white rust of up to 10 area% after 2 days. Such coatings are not usable in European industry for any use.

Inventive Example B 0:

In comparison, an aqueous solution with an addition of zinc dihydrogen phosphate (60%) in the range of 40 to 60 g / L, with an addition of a corresponding molar amount of orthophosphoric acid, to 25 g / LH ₂ TiF ₆ (50 % ig), to 6 g / L of γ-APS (γ-aminopropyltriethoxysilane) and with deionized water as the remainder for coating hot dip galvanized sheets by RoII coaten in the laboratory used. There were coatings of about 110 to 165 mg / m ² P ₂ O ₅ , 36 mg / m ^{2 of} Ti and 6 mg / m ^{2 of} Si. These coatings showed in the neutral salt spray test (NSS test) according to DIN EN ISO 9227 (blank corrosion test) only after 48 to 72 hours on the entire surface related corrosion attack of 1 to 5 area%, although no chromium was included in the coating , For high demands in the European industry resistances in the NSS test over 2 days, rarely over 3 or 4 days, with corrosion phenomena <5 area% are demanded today. Such blank corrosion resistance is usually achieved only with chromium-rich systems. With the process of the present invention, blank corrosion resistances of 2 to 5 days were achieved, with the substrates and compositions being varied. In the case of the condensed water constant climate test according to DIN EN ISO 6270-2 (KK test), however, the improvement compared to comparative example VB 0 is significantly lower than with the neutral salt spray test (NSS test). Even after 10 days of KK testing, no rust had formed.

Inventive Examples B 1 - B 44 and Comparative Examples VB 1 to VB 4: Aqueous compositions were mixed whose compositions are shown in Tables 1 as concentrates. The dilution factor illustrates the dilution to the bath concentration used, that is from a concentrate to a bath, so that for example a concentrate used 200g and diluted with water to 1000g using dilution factor 5. Aluminum was used as monoaluminum phosphate, chromium as complexed chromium (III) fluoride or / and chromium (III) phosphonate, iron as iron (III) nitrate hydrate, manganese as manganese carbonate and / or manganese oxide, zinc as mono zinc phosphate or zinc oxide. As silanes there were added as No. 1) 3-aminopropylthethoxysilane (APS), as No. 2) N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (AEAPS) and as No. 3) tetraethoxysilane (TEOS). The complexing agents used as No. 1) were 1-hydroxyethane-1,1-diphosphonic acid (HEDP) and No. 2) phytic acid. The inhibitors which were added as No. 1) polymeric quaternary ammonium salt, as No. 2) quaternary ammonium salt, as No. 3) polyvinylpyrrolidone and as No. 4) tetraethanolamine. Hexafluorotitanic acid, hexafluorozironic acid or dihydroxo bis (ammonium lactate) titanate were added as the titanium or zirconium compound. The wax used was a wax emulsion based on oxidized polyethylene. In order to further lower the coefficient of friction of the coating according to the invention, it is also possible to add at least one glycol, in particular at least one polyethylene glycol. The adjustment of the pH was optionally carried out by means of aqueous ammonia solution. The pH ranges are valid for both concentrates and bath concentrations. When diluting the concentrates to make bath solutions, care was taken to avoid precipitation. Concentrates and bath solutions were stored at room temperature for one to 24 hours before use.

Then, in each case at least 9 plates made of hot-dip galvanized steel (HDG) in Examples B 1 to B 26 and B 36 to B 44 and in Comparative Examples VB 1 to VB 4, sheets of Galvalume ^® (AZ) in Examples B B 27 to 32, sheets of Galfan ^® (ZA) in Example B 33 or sheets of AIu- si ^® (AS) in Examples B 34 and B 35 are used. Most of the samples used high quality HDG (HDG / 3) sheets, which are referred to in the tables as HDG, while also using a lower quality coil ("HDG / 4").

The sheets were pre-cleaned with a cloth to largely remove adherent corrosion protection oil and to achieve an even distribution of the oil or other contaminants. Subsequently, the panels were spray-cleaned with a mildly alkaline, silicate-free powder cleaner until complete wettability with water was present. The duration for this was generally 20 to 30 s. This was followed by rinsing with city water in the dipping, rinsing with city water for 6 s by spraying and rinsing with demineralised water for 6 s. The majority of the adhered water was then removed from the sheets by squeezing between two rubber rolls. Subsequently, the sheets were blown dry with oil-free compressed air.

The dry sheets were brought into contact with the aqueous composition of about 25 ^° C. with the aid of a laboratory roll coater. The pH of the compositions was determined with pH indicator paper. A wet film of about 9 to 10 μm thickness was applied. By drying this wet film, a dry film of 0.2 to 0.6 μm in thickness was produced. For this purpose, the sheets treated in this way were dried at about 40 or 65 ^° C. PMT. Subsequently, the edges of the coated sheets were taped with commercially available adhesive tape to exclude edge effects during the corrosion test.

The coated sheets were then tested for their blank corrosion protection in the condensed water constant climate test (KK test) in accordance with DIN EN ISO 6270-2 and in the neutral salt spray test (NSS test) in accordance with DIN EN ISO 9227. The evaluation was done visually. The values given for the corrosion correspond to the percentage of the surface area which corresponds to the total corresponds to the area of chemical exposure (100%). In Galvalume ^® -Blechen "black rust" and "white rust" were evaluated in total. The results of the corrosion tests illustrate the range of corrosion protection, using all measurement results including the measured values, which are to be regarded as outliers.

In comparative examples VB 5 to VB 7, electrolytically galvanized sheets (ZE) were brought into contact with typical zinc-containing phosphating solutions after prior mild-alkaline cleaning, rinsing with tap water and activation with titanium phosphate. The phosphating was carried out in Comparative Examples VB 5 and VB 6 at temperatures ranging from room temperature to 40 ⁰ C by spraying and rinsing (rinse method), in the Comparative Example CE 7 at 55 to 60 ⁰ C by rolling and drying (no-HNSE method). The former were also oiled or rinsed.

Table 1: Overview of the compositions of the solutions used and their composition and the properties of coatings produced therewith and of corresponding compositions for comparison

The coatings according to the invention showed a layer weight in the range from 350 to 650 mg / m ² total circulation and a thickness approximately in the range of 0.2 to 0.6 microns. They were produced so thin and so fast that the substances in the coatings are not sufficiently crystalline to be determined by X-ray analysis. Scanning electron micrographs of these coatings essentially reveal the topography of the cleaned metallic substrate surface. The applied coatings according to the invention have not been significantly topographically imaged under the scanning electron microscope. The coatings are apparently homogeneous transparent layers. Depending on the substrate type and coating, they give the metallic surface a light matte finish, just as well as without a coating or with a stronger shine. The coatings are usually without color cast.

In another series, a powder coating based on polyester in a layer thickness of about 80 microns thickness was applied to the hot-dip galvanized and pretreated sheets based on the composition of B 10. In the following cross-cut test of the painted sheets according to DIN EN ISO 2409, a value of Gt 0 always resulted before the corrosive action.

The compositions in Examples B 1 to B 6 each contain aluminum and zinc whose contents have been varied. The KK test for 10 days on the associated coatings was flawless. In the case of the examples B 7 to B 13 containing only zinc as cation, in particular PO ₄ content, Ti content, pH value, complexing agent type and silane type were varied. At lower phosphate content, the corrosion protection may decrease. This may particularly affect the results of the KK test. The complexing agent 1) behaved better than the complexing agent 2). The silanes 1) and 2) behaved slightly better than the silane 3). Examples B 14 and B 15 selected zinc and manganese as cations. This is fit that the manganese content does not deteriorate the corrosion protection. Examples B 16 and B 17 compare the addition of a titanium compound with the addition of a zirconium compound. The addition of a titanium compound enables significantly higher corrosion protection on hot-dip galvanized surfaces. In Examples B 18 to B 21, various corrosion inhibitors were additionally used. The corrosion inhibitors improve the corrosion protection, with the corrosion inhibitor 4) acting somewhat less protective. The addition of tannin in Example B 22 brought no significant improvement. In Examples B 23 to B 26, the additions of cations were varied. The addition of chromium (III) improved the corrosion protection very clearly. The use of only iron cations was less successful for corrosion protection. In Examples B 27 to B 32 Galvalume ^®, an excellent corrosion protection showed. An addition of silane is not necessary for Galvalume ^® surfaces, but it is advantageous for a high corrosion protection. Example B 33 proves that even on Galfan ^® - surfaces good corrosion protection results are obtained. For examples B 34 and B 35 for Alusi ^® surfaces, it must be ensured that the cation and phosphate content is not too low. In examples B 36 to B 44, hot-dip galvanized surfaces were again coated. In Examples B 36 to B 41 was worked with or without silane and with varying titanium compound content. The addition of silane or an increased titanium compound content resulted in better corrosion protection. The complexing agent 1) usually behaves better than the complexing agent 2). The replacement of titanium complex fluoride by a titanium chelate in Example B 42 resulted in excellent corrosion protection for a silane-free and fluoride-free composition. In Examples B 43 and B 44, only aluminum was used as cations. The associated coatings appeared a bit dull. The corrosion protection was good.

The blank corrosion protection of the examples according to the invention determined in the NSS test is usually better at least by the time factor 20 or 30 than with comparable zinc-phosphated coatings. As the main cause For this purpose, it is assumed that the coating according to the invention is unusually closed and free of pores.

Claims

claims

A process for coating metallic surfaces with an aqueous composition as a solution or dispersion, characterized in that the composition comprises at least one phosphate, at least 3 g / L of at least one titanium and / or zirconium compound, at least one complexing agent and cations of aluminum , Chromium (III) or / and zinc or / and at least one compound containing aluminum, chromium (III) or / and zinc, and that a wet film of the aqueous composition is dried on metallic strips or sheets.

2. The method according to claim 1, characterized in that the composition additionally contains cations of iron and / or manganese and / or at least one compound containing iron or / and manganese.

3. The method according to claim 2, characterized in that the composition has a total content of cations of aluminum, chromium (III), iron, manganese and / or zinc and / or at least one compound containing aluminum, chromium (III), iron , Manganese or / and zinc in the range of 1 to 100 g / L calculated as metal.

4. The method according to any one of the preceding claims, characterized in that the composition contains substantially only cations of aluminum, iron, manganese, titanium, zinc and / or zirconium.

5. The method according to any one of the preceding claims, characterized in that the composition contains a content of phosphate in the range of 1 to 400 g / L calculated as PO ₄ .

6. The method according to any one of the preceding claims, characterized in that the composition contains a total content of at least one complexing agent in the range of 1 to 200 g / L.

7. The method according to any one of the preceding claims, characterized in that the composition contains a total content of at least one titanium and / or zirconium compound based on complex fluoride in the range of 1 to 200 g / L.

8. The method according to any one of the preceding claims, characterized in that the composition has a content of free fluoride F _freι in the range of 0.01 to 5 g / L or / and a content of total fluoride

Total in the range of 3 to 180 g / L.

9. The method according to any one of the preceding claims, characterized in that the composition contains at least one compound based on phosphonic acid and / or at least one compound based on carboxylic acid.

10. The method according to any one of the preceding claims, characterized in that the composition contains at least one compound based on phytin or / and tannin.

11.A method according to any one of the preceding claims, characterized in that the composition contains at least one silane / silanol / siloxane / polysiloxane.

12. The method according to claim 11, characterized in that the composition contains a content of at least one silane / silanol / siloxane / polysiloxane in the range of 0.1 to 200 g / L, calculated on the basis of silane or polysiloxane of the respective starting compound.

13. The method according to any one of the preceding claims, characterized in that the composition contains at least one organic monomer / oligomer / polymer / copolymer.

14. Process according to claim 13, characterized in that the composition comprises at least one organic monomer / oligomer / polymer / copolymer based on or / and containing (meth) acryl, epoxide, ethylene, polyester or / and urethane.

15. The method according to any one of the preceding claims, characterized in that the composition contains at least one inorganic see and / or organic compound in particulate form.

16. The method according to claim 15, characterized in that the composition contains at least one inorganic compound in particle form based on Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, ZrO ₂ or / and corrosion protection particles having an average particle diameter of less than 300 nm measured under a scanning electron microscope.

A method according to any one of the preceding claims, characterized in that the composition comprises at least one additive, e.g. each contains at least one wetting agent, a demulsifier, an emulsifier, a defoamer, a corrosion inhibitor and / or a wax.

18. The method according to any one of the preceding claims, characterized in that the composition has a pH in the range of 0 to 10.

19. The method according to any one of the preceding claims, characterized in that as a metallic surface such on the basis of aluminum, iron, magnesium, titanium, zinc and / or tin are treated with the aqueous composition, in particular parts, bands and / or sheets ,

20. An aqueous composition according to any one of claims 1 to 19.

21. Coating produced by a process according to any one of claims 1 to 19 and / or with an aqueous composition according to claim 20.

22. Use of the coated according to the method according to claims 1 to 19 metallic components in vehicle construction, as architectural elements in construction or for the manufacture of equipment and machinery such. Domestic appliances.