WO2016193004A1

WO2016193004A1 - Conditioning prior to a conversion treatment of metal surfaces

Info

Publication number: WO2016193004A1
Application number: PCT/EP2016/061208
Authority: WO
Inventors: Kevin D. Murnaghan; Michiel Gerard MAAS; Sophie Cornen; Isabel Kinscheck
Original assignee: Henkel Ag & Co. Kgaa
Priority date: 2015-05-29
Filing date: 2016-05-19
Publication date: 2016-12-08
Also published as: DE102015209909A1

Abstract

The invention relates to a multi-step process for the anti-corrosive pretreatment of components which consist of metallic materials. The components are first subjected to a conditioning wet-chemical treatment with an aqueous composition (A) that contains a conditioner and then to an additional wet-chemical treatment based on water-soluble compounds of the elements Zr, Ti and/or Si, in the course of which treatment a corresponding conversion of the surfaces of the metallic materials takes place, said treatment providing an anti-corrosive primer for additionally applied organic coatings.

Description

Conditioning before a conversion treatment of metal surfaces

The present invention relates to a multi-stage process for the corrosion-protective pretreatment of components made of metallic materials, wherein on a conditioning wet-chemical treatment with an aqueous composition (A) containing a conditioner, a further wet-chemical treatment based on water-soluble compounds of the elements Zr, Ti and / or Si follows, in the course of which a corresponding conversion of the surfaces of the metallic materials takes place, which is a corrosion-protecting primer for additionally applied organic

Coatings mediated.

The conversion treatment of metallic surfaces to provide a corrosion-protective coating based on aqueous compositions containing water-soluble compounds of the elements Zr, Ti and / or Si is a technical field extensively described in the patent literature. To improve the property profile of such conversion treatments in terms of corrosion protection and imparting sufficient paint adhesion, various variants of such metal pretreatment are known, which either aim at the composition of the conversion-causing agents or resort to further wet-chemical treatment steps in the immediate context of the conversion treatment.

EP 1 455 002 A1 describes, for example, that it is advantageous for conversion treatment by means of previously described compositions which additionally contain fluoride ions as complexing agent and metal-oxide-containing agent to reduce the fluoride content in the conversion layer of the actual wet-chemical treatment aqueous sink containing basic compounds immediately following or a drying step is downstream. Alternatively, the reduction of the fluoride content in the conversion layer serves the addition of certain cations selected from calcium, magnesium, zinc, copper or silicon-containing compounds for the conversion of the surface inducing

Composition. With regard to further adaptations of the process sequence in the use of fluoride ions and water-soluble compounds of the elements Zr and / or Ti containing conversion treatment agents, WO 201 1012443 A1 teaches a downstream aqueous sink containing organic compounds having aromatic heterocycles with at least one nitrogen heteroatom ,

Compared to this prior art, the object was to further unify the anti-corrosive properties of conversion layers on various metal substrates obtainable by pretreatment with compositions of water-soluble compounds of the elements Zr, Ti and / or Si and in particular to the

To improve steel surfaces. Here, in particular, the average undermigration values in the corrosive delamination after coating layer build-up should be improved. In one aspect, the pretreatment for environmental health reasons should be largely without the presence of fluorides. A

Pretreatment method according to the present invention must, therefore, in order to realize this aspect, even in the absence of fluorides, a homogeneous and complete conversion of the so-called "free metal surface" so the degreased, purified and having only the natural oxide layer

Effect metal surface. Furthermore, under identical process conditions, a small variance in the conversion layer should result, ie a certain conversion can be reliably achieved in terms of process engineering. With regard to the application to various metal substrates in particular an optimal corrosion protection effect of such composite structures by means of a corresponding wet-chemical pretreatment is desired, which in addition to surfaces of the material iron and / or steel and surfaces of at least one of the materials zinc, galvanized steel and / or aluminum.

This object is achieved by a multi-stage process for corrosion-protective pretreatment of at least partially made of metallic materials

Components in which initially

i) at least part of the surfaces of the component other than the metallic ones

Materials comprising an aqueous composition (A) containing a conditioner which is a source of anions selected from monoalkyl sulfates, and / or monoalkyl sulfonates, and subsequently

ii) at least the same part of the surfaces of the component formed by the metallic materials, with or without intermediate rinsing and / or drying step with an aqueous composition (B) containing one or more water-soluble compounds of the elements Zr, Ti and / or Si is brought into contact.

The treated according to the present invention components can be any arbitrarily shaped and designed spatial structures that originate from a fabrication process, in particular also semi-finished products such as strips, sheets, rods, tubes, etc. and

Composite structures assembled from the aforementioned semi-finished products.

According to the invention, in the first step i) of the process according to the invention, a treatment is carried out with the aqueous composition (A) containing the conditioner. This treatment causes, in the course of the wet-chemical treatment with an aqueous composition (B), a sufficient and homogeneous

Coating is achieved with respect to the elements Zr, Ti and / or Si, so that a conversion of the metal surfaces of the component is effectively carried out, which provides a potentially good Lackhaftgrund. In particular, on steel surfaces is achieved in the course of the inventive method, a reproducible layer support with respect to the elements Zr, Ti and / or Si, which is the basis for effective suppression of corrosive infiltration of defects in an additionally applied

Represents paint coating.

Insofar as in the present case in step i) of the method according to the invention of the presence of a conditioner is mentioned, so are only those chemical compounds comprising selected in water in anions of monoalkyl sulfates and / or

Monoalkylsulfonaten able to dissociate or selbige anions can give off in the aqueous phase and thus represent a source of these anions. The conditioner contained in the aqueous composition (A) in step i) is therefore preferably dissolved and / or dispersed in water. A conditioner dissolved or dispersed in water according to the invention takes in the aqueous phase an average particle diameter of less than 1 μm. The middle one Particle diameter can be determined according to ISO 13320: 2009 by means of laser light diffraction from cumulative particle size distributions as a so-called D50 value directly in the aqueous composition (A) at 20 ° C.

The conditioner in the aqueous composition (A) is preferably selected from salts of monoalkyl sulfates and / or monoalkyl sulfonates, more preferably salts of monoalkyl sulfates, each preferably not more than 5

Carbon atoms in the alkyl radical, and particularly preferably selected from salts of methyl sulfate and / or ethyl sulfate and the corresponding acids. Preferred salts are in particular salts of alkali metals and / or alkaline earth metals and the corresponding ammonium salt and / or salts of quaternary organic amines, particular preference is given to the corresponding salts of quaternary organic amines.

Furthermore, it has been found that it is generally advantageous according to the invention if the proportion of the conditioner calculated as the equivalent amount of SO _{4 is} preferably at least 0.05 g / kg, more preferably at least 0.2 g / kg, particularly preferably at least 0.4 g / kg, but preferably not greater than 5 g / kg, more preferably not greater than 3 g / kg, based in each case on the aqueous composition (A). Above 5 g / kg, even if the conditioning in step i) is followed by a rinsing step, no further increase or homogenization of the conversion layer formation in step ii) is effected, so that any amount of conditioner beyond this would be used uneconomically in the process according to the invention.

Surprisingly, the presence of quaternary organic amines increases the suitability of the conversion coating applied in step ii)

Lackhaftgrund to be. In addition, in step ii) a further acceleration of the conversion layer formation is observed, which is necessary for a good corrosion protection. Consequently, the aqueous composition (A) in step i) in a preferred embodiment of the process according to the invention also contains at least one quaternary organic amine. A quaternary organic amine in the context of the present invention contains at least one nitrogen atom which has exclusively covalent bonds with carbon atoms and therefore possesses a permanent positive charge. In this context, it has been found preferable if the quaternary organic amine is at the same time the cationogenic constituent of the conditioner, the same being both source of the monoalkylsulfate anion and / or monoalkylsulfonate anion and source of the corrosive deletion suppressing quaternary organic amine and the ionic freight in the aqueous composition (A) thus can be reduced to a minimum.

The quaternary organic amines may also be a structural component of polymeric compounds, although in the context of the present invention preferably such quaternary organic amines are included in the aqueous composition whose weight average molecular weight M _{w is} less than 5,000 g / mol.

Furthermore, it has been found that especially heterocycles with at least one

Nitrogen heteroatom having exclusively covalent bonds with carbon atoms, suitable quaternary organic amines, so that they are preferred in a method according to the invention as part of the aqueous composition (A).

In a preferred embodiment, a quaternary organic amine contained in the aqueous composition (A) is a heterocycle having at least one nitrogen heteroatom of the following structural formula (I):

with the radicals R ¹ , R ² and R ³ , which are each selected from hydrogen, branched or unbranched aliphatics having not more than 6 carbon atoms or the radical - (CR ⁴ R ⁴ ) x- [Z (R ⁴ ) ₍ pi) - (CR ⁴ R ⁴ ) y] n Z (R ⁴ ) _p , wherein each Z is selected from oxygen or nitrogen and p in the case where Z is nitrogen, takes the value 2 and otherwise equals 1 and x and y respectively natural numbers from 1 to 4 and n as well is a natural number from 0 to 4 and R ^{4 is} selected from hydrogen or branched or unbranched aliphatics having not more than 6 carbon atoms, with the proviso that at least one of R ² or R ^{3 is} not selected from hydrogen;

with Y as the ring-constituting divalent radical having not more than 5 bridging atoms, wherein not more than one of carbon atoms

Heterobridatom selected from oxygen, nitrogen or sulfur can be bridging atom and the carbon atoms in turn independently of one another with radicals R ¹ or such radicals substituted, via which a Anellierung of aromatic homocycles having not more than 6 carbon atoms is realized.

In principle, it has proven advantageous that the quaternary organic amine is represented by such heterocycles having the backbone of imidazole, imidazoline, pyrimidine, purine and / or quinazoline. In this connection, it is therefore preferred that the heterocycle according to the structural formula (I) be used as

ring-constituting divalent radical Y has such substituents selected from ethylene, ethenediyl, 1, 3-propanediyl, 1, 3-Propendiyl, 1, 4-butanediyl, 1, 4-butenediyl, 1, 4-butadiendiyl, -CH = N -, -CH ₂ -NH-, (N, N-dimethylene) amine, (N-methylene-N-methyllyliden) amine, more preferably from ethenediyl, 1, 4-butadiendiyl, -C = N- or (N-methylene N-methyllyliden) amine, most preferably from ethenediyl or -C = N- and particularly preferably from etendiyl, wherein each hydrogen covalently bonded to carbon atoms may be substituted by the remaining representatives of the radical R ¹ according to the general structural formula (I).

Particularly advantageous are those quaternary organic amines have been found which is selected from 1, 2,3-trimethylimidazolium, 1-methyl-3-methylimidazolium,

1-ethyl-3-methylimidazolium, 1-isopropyl-3-methylimidazolium,

1-propyl-3-methylimidazolium, 1- (n-butyl) -3-methylimidazolium,

1- (isobutyl) -3-methylimidazolium, 1-methoxy-3-methylimidazolium,

1-ethoxy-3-methylimidazolium, 1-propoxy-3-methylimidazolium, more preferably from 1, 2,3-trimethylimidazolium. As discussed above, the counterions to the quaternary organic amine are, in particular, the anions for which the conditioner is intended to be a source, ie anions selected from monoalkyl sulfates and monoalkyl sulfonates and the further preferred representatives, which have already been specified in the context of the conditioner , and therefore are also preferred in this aspect of the present invention.

According to the invention, it is generally advantageous if the proportion of the quaternary organic amine in the aqueous composition (A) is at least 0.05 g / kg, preferably at least 0.2 g / kg, more preferably at least 0.4 g / kg, however

preferably not greater than 5 g / kg, more preferably not greater than 10 g / kg. Above 10 g / kg, even if the conditioning in step i) is followed by a rinsing step, no further suppression of corrosive softening by coating composition is observed, so that any amount of quaternary organic amine beyond this would be used uneconomically in the process according to the invention.

The pH of the aqueous composition (A) in step i) can be chosen freely as far as possible and is usually in the range from 2 to 14, preferably above 3.0, more preferably above 4.0, particularly preferably above 5, 0, but preferably below 12.0, more preferably below 10.0, and most preferably below 8.0.

The aqueous composition (A) may contain further components according to the invention. In addition to the pH-regulating substances can do this too

be surface-active substances whose use in a composition (A) having a cleaning action is preferred.

In addition, it may be beneficial for the treatment of components that

Surfaces of the materials Zinc and / or galvanized steel have the additional advantage that the aqueous composition (A) contains a quantity of iron ions which, when in contact with the zinc surfaces, causes a thin coating of iron there, thereby additionally contributing to the standardization of the corrosion protection in the process according to the invention is accessible in particular for surfaces of the material iron. A Such icing can, according to the teaching of WO 2008135478 A1 in an acidic medium, preferably in the presence of a reducing agent or according to the teaching of

WO 201 1098322 A1 in an alkaline medium, preferably in the presence of

Complexing agents and phosphate ions take place.

However, it is preferred if the aqueous composition (A) in step i) of the process according to the invention is less than 0.5 g / kg, more preferably less than 0.1 g / kg, particularly preferably less than 0.05 g / kg contains dissolved and / or dispersed organic polymers containing no quaternary organic amines, as previously associated with the positive effect on the ligation of the corrosive

Enthaftung impacting quaternary organic amines described represent.

This ensures that the interaction of such polymers with the surfaces of the metallic materials of the component does not match that of the

Conditioner or in a preferred embodiment of the present invention additionally contain quaternary organic amines in competition and thereby counteracts the respective desired technical effect. One in this

Organic polymer dissolved or dispersed in the context of the invention has an average particle diameter of less than 1 μm in the aqueous phase. The mean particle diameter can according to ISO 13320: 2009 means

Laser light diffraction from cumulative particle size distributions as a so-called D50 value directly in an aqueous composition (A) at 20 ° C are determined.

In a preferred method according to the invention, no conversion layer is produced on the surfaces of the metallic components in step i). Accordingly, the aqueous composition (A) does not contain any components in an amount that can do so during the conditioning step i)

Period form a conversion layer on a surface of a metallic material of the component. A conversion layer in the course of the conditioning in step i) of the method according to the invention is present when a cover layer is produced wet-chemically on the respective surface of the metallic material, the phosphates, oxides and / or hydroxides of elements of the titanium group, vanadium group and or chromium group or phosphates of the elements calcium, iron and / or zinc in a layer of at least 5 mg / m ² based on the respective subgroup element or of at least 50 mg / m ² drawn on the element phosphorus. The Corresponding subgroup elements can be determined quantitatively by X-ray fluorescence analysis (XRF), while the layer coverage with respect to the element phosphorus can be determined quantitatively by pickling the surfaces of the metallic materials in aqueous 5% by weight OO 3 and subsequent atomic emission spectroscopy (ICP-OES).

An inventive method is to prevent the formation of a

Conversion layer on the surfaces of the metallic materials of the component preferably characterized in that the aqueous composition (A) in step i) each less than 0.005 g / kg, more preferably in each case less than

0.001 g / kg of water-soluble compounds of the elements Zr, Ti and / or Si based on the respective element, preferably less than 1 g / kg of water-soluble compounds of the elements Zn, Mn and Ca based on the respective element and / or preferably less than 0.05 g / kg, more preferably less than 0.01 g / kg of free fluoride determined with a fluoride-sensitive electrode at 20 ° C. In a further preferred embodiment, the total content of fluorides in the aqueous

Composition (A) less than 0.05 g / kg, more preferably less than

0.02 g / kg, more preferably less than 0.01 g / kg. The total content of fluorides (total fluoride) is in a TISAB buffered aliquot of the aqueous

Composition (A) determined with a fluoride-sensitive electrode at 20 ° C (TISAB: "Total Lonic Strength Adjustment Buffer"), where the volume-related

Mixing ratio of buffer to the aliquot part of the aqueous composition (A) is 1: 1. The TISAB buffer is prepared by dissolving 58 g NaCl, 1 g

Sodium citrate and 50 ml of glacial acetic acid in 500 ml of deionized water (κ <Ι μεοητ ¹ ) and adjusting a pH of 5.3 using 5 N NaOH and filling to a

Total volume of 1000 ml in turn with deionized water (κ <Ι μεοητ ¹ ).

In method step ii), an amount of active components sufficient to form a conversion layer should be present in the acidic aqueous composition (B). In this regard, it is advantageous if the aqueous composition (B) in step ii) preferably at least 0.01 g / kg, more preferably at least 0.05 g / kg, particularly preferably at least 0.1 g / kg of water-soluble compounds of the elements Zr , Ti or Si based on the respective element Zr, Ti or Si. In this context, it should be noted that such compounds according to of the present invention are considered to be water-soluble if their solubility in deionized water (κ <1 μεοητ ¹ ) is at least 1 g / L at 20 ° C.

For economic considerations, it is also advantageous if the

The total content of these compounds based on the elements Zr, Ti and Si is preferably not greater than 0.5 g / kg, since higher contents usually do not further improve the anti-corrosive properties of the conversion layer, but due to the higher deposition kinetics make it difficult to control the layer support with respect to these elements ,

Owing to the conditioning in step i) of the process according to the invention, fluorine-free water-soluble compounds of the elements Zr, Ti or Si in the aqueous composition (B) are also suitable for achieving a sufficient conversion of the compounds

Surfaces of the metallic materials of the component and are therefore preferred.

Particularly preferred representatives are (NH ₄ ) 2Zr (OH) 2 (CO ₃ ) 2, ZrO (NO ₃ ) 2 or TiO (SO ₄ ) or silanes having at least one covalent Si-C bond.

As already stated, the use of complex fluorides and also free fluorides in step ii) for effecting the conversion of the surfaces of the metallic materials of the components can be dispensed with in the present inventive method due to the conditioning in step i). Accordingly, such methods

preferred in the invention in which the proportion of free fluoride in the aqueous composition (B) with increasing preference is less than 0.05 g / kg, 0.01 g / kg, 0.001 g / kg and 0.0001 g / kg and whole particularly preferably no free fluoride is contained. Furthermore, in a preferred embodiment of the method according to the invention, the total content of fluorides (total fluoride) in the aqueous

Composition (B) with increasing preference less than 0.05 g / kg, 0.02 g / kg, 0.01 g / kg, 0.001 g / kg and 0.0001 g / kg, and most preferably no fluoride is included. The proportion of free fluoride and the total content of fluorides can analogously to the procedure for determining the same parameters in the aqueous

Composition (A) can be determined.

In combination with the conditioning in step i) the best results in terms of corrosion protection are achieved when in the aqueous composition (B) in step ii) copper ions are contained. In a particularly preferred embodiment of the method according to the invention, the aqueous

Composition (B) therefore additionally water-soluble compounds which are a source of copper ions, preferably in the form of water-soluble salts, for example copper sulfate, copper nitrate and copper acetate. In this context, it should be noted that such compounds according to the present invention are considered to be water-soluble, if their solubility in deionized water (κ <Ι μεοητ ¹ ) is at least 1 g / L at 20 ° C.

The content of copper of water-soluble compounds in the aqueous composition (B) is preferably at least 0.001 g / kg, more preferably at least 0.005 g / kg. However, the content of copper ions is preferably not above 0.1 g / kg, more preferably not above 0.05 g / kg, otherwise the deposition of elemental copper begins to dominate over the conversion layer formation.

The pH of the aqueous composition (B) is preferably in the acidic range, more preferably in the range of 2.0 to 5.0, particularly preferably in the range of 2.5 to 3.5.

It is further preferred if the aqueous composition (B) contains nitrate ions as an accelerator of the conversion layer formation, wherein the proportion of nitrate ions is preferably at least 0.5 g / kg, but for reasons of economy preferably does not exceed 4 g / kg.

Surprisingly, the success of the invention occurs largely independently of the performance of one of the conditioning in step i) immediately following rinsing and / or drying step. Differences in the performance of the process caused by an intermediate rinsing step can be regularly absorbed by a moderate increase in the concentration of conditioner and / or quaternary organic amine contained in the aqueous composition (A). The general suitability of the method to solve the problem underlying the invention remains, in any case, from the implementation of a between the Process steps i) and ii) rinsing and / or drying step unaffected. However, in terms of process technology, it is preferred that, for the separation of the active components in the individual treatment steps, the step i) in an inventive

Procedure immediately followed by a rinsing step, preferably before step ii) no drying step takes place.

A rinsing step according to the invention is always the removal of water-soluble residues, not firmly adhering chemical compounds and loose solid particles from the component to be treated, which consists of a previous wet-chemical

Treatment step are removed with the adhesive on the component wet film, by means of a water-based liquid medium. The water was based

Liquid medium contains no chemical components that have a significant surface coverage of the components made of metallic materials

Subgroup elements, semi-metal elements or polymeric organic

Make connections. Such significant surface coverage is in any case when the liquid medium of the sink by at least 10 milligrams per

Square meters of the rinsed surfaces, preferably at least 1 milligram per square meter of the rinsed surfaces, depleted of these components relative to the particular element or polymeric organic compound, without taking into account gains from carryover and losses due to removal of wet films adhering to the component.

According to the invention, a drying step is any method step in which the provision and use of technical means is intended to dry the aqueous liquid film adhering to the surface of the component, in particular by supplying thermal energy or impressing an air flow.

The components that are treated in the method according to the invention, at least partially made of metallic materials. Preferred metallic materials for which an improvement in the properties of the conversion layer as a lacquer adhesion base is clearly evident are iron and alloys of iron, in particular steel. In this context, alloys of iron are materials which are formed by at least 50 at.% Of the respective material of iron atoms. On surfaces In the case of iron and its alloys, a significant improvement in corrosion protection occurs in the corrosive infiltration of paint defects, which even occurs largely independently of whether a rinsing and / or drying step follows immediately after the conditioning in step i).

In the process according to the invention, step ii) is preferably followed by the application of an organic coating, especially a powder coating or dip coating, which in turn is preferably an electrodeposition paint. The electrocoating follows

preferably a rinsing step, but more preferably no drying step.

In a preferred embodiment of the method according to the invention, the component at least partially surfaces of the materials iron and / or steel, preferably at least 50%, more preferably at least 80% of the surface of the component, the surfaces of metallic materials, from surfaces of the materials iron and / or steel are formed.

In principle, however, can also composite structures and in particular components that in addition to surfaces of the materials iron and / or steel and surfaces of the materials zinc and / or galvanized steel and aluminum, which may additionally

phosphated may be treated in the process according to the invention.

Furthermore, in the case where the component has surfaces of the materials zinc and / or galvanized steel, it is generally preferred that same surfaces be treated with a thin amorphous layer containing iron, so that the surfaces of these materials have an equally effective conditioning in step i ) of the method according to the invention, as is commonly found for the surfaces of the materials iron and / or steel. In this regard, a particularly effective icing of the surfaces of zinc and / or galvanized steel is described in the published patent applications WO 201 1098322 A1 and WO 2008135478 A1 as a wet-chemical method, which in an equivalent manner immediately before the execution of the

Method step i) according to the invention can be used. In this respect, it is for inventive method in which the component at least partially from the

Zinc and / or galvanized steel, it is preferred that the surfaces of the Component, which are made of these materials, an iron occupancy of at least 20 mg / m ² , but preferably not more than 150 mg / m ² have.

EXAMPLES

In the following, steel sheets (CRS) are subjected to a multi-stage process for corrosion-protective pretreatment. The suitability of such pretreated and provided with a paint layer metal sheets to represent a good Lackhaftgrund is tested in a test according to DIN EN ISO 4628-8 for corrosive Abstaltung.

The general procedure for pretreatment and coating consists of the successive obligatory and optional steps (A) - (E):

(A) Alkaline cleaning and degreasing:

Immerse the plate with stirring in an alkaline cleaner

composed of 4% by weight Ridoline® 201 1 (Henkel) and

0.4% by weight Ridosol® 1270 (Henkel) for 5 minutes at 56 ° C .;

(B) rinse with hot water and then with deionized water (K <1 μεοητ ¹ ) at 20 ° C;

(C) Conditioning by immersing the sheet for 1 minute at 35 ° C in a

Composition containing a predetermined amount of a "conditioner" in deionized water (κ <1 μεοητ ¹ ) without further addition of pH-changing substances;

(D) if necessary, rinse with deionized water at 20 ° C (κ <1 μεοητ ¹ );

(E) Conversion treatment by immersing the sheet for 3 minutes at 35 ° C in an aqueous composition having a pH of about 2.6 containing 1.6 g / kg of ZrO (NO ₃ ) ₂ .

After the conversion treatment in process step (E), the respective sheet was first rinsed with deionized water (κ <Ι μεοητ ¹ ) at 20 ° C and then coated with a cathodic dip coating and dried at 180 ° C.

(Dry film thickness: 18-20 μm, CathoGuard® 800 from BASF Coatings). Table 1 below shows the various organic compounds used in the conditioning in step (C).

Tab. 1

Used compositions in conditioning

^* Polyvinyl pyrollidone (Mw ~ 160,000 g / mol)

It becomes clear that on steel sheets in the attempt of a pure

Conversion treatment based on a fluoride-free composition in step (D) can not be realized reproducibly a coating layer in the range of 0-20 mg / m ² of zirconium (No. 1). Likewise, conditioning on the basis of a pretreatment with an aqueous solution containing polyvinylpyrollidone (No. 2) fails because the conversion layer formation is neither increased nor reproducible overall. Only the addition of sodium methyl sulfate causes with increasing concentration a significant conversion of the steel surfaces, so that a usually sufficient for a good corrosion protection and Lackhaftgrund coating weight in the range of 15-25 mg / m ^{2 is} easily achieved (No.3). In addition, when using quaternary amine based conditioners as the source of the methylsulfate anion, a strong improvement in cut corrosion can be observed (Nos. 4-5), with the heterocyclic quaternary organic amine in particular providing good results (# 5) ). The corrosion results and the associated process sequence are given in Table 2.

Tab. 2

Corrosion results on the pretreated and accordingly

electrocoated sheets

Corrosion on the section in accordance with DIN EN ISO 4628-8, after removal in the alternating climate test VW according to PV 12103

² average and standard deviation over 5 sheets, whereby for the layer support of each sheet the averaged value

6 single measurements on the same plate and the determination in each case by means of X-ray fluorescence analyzer Niton® XL3t 900 (Thermo Fisher Scientific) with a

Analysis area of 50 mm ^{2 was} made.

# Mean and standard deviation over 62 sheets

Claims

claims

1. Multi-stage process for corrosion-protective pretreatment of at least partially made of metallic materials components, wherein initially i) at least a part of the surfaces of the component, which are formed by the metallic materials, with an aqueous composition (A) containing a conditioner, the one Source of anions selected from monoalkyl sulfates, and / or monoalkyl sulfonates,

and subsequently

ii) at least the same part of the surfaces of the component, which are formed by the metallic materials, with an aqueous composition (B) containing one or more water-soluble compounds of the elements Zr, Ti and / or Si is brought into contact.

2. The method according to claim 1, characterized in that the conditioner in the aqueous composition (A) is selected from salts of

Monoalkyl sulfates and / or monoalkyl sulfonates, preferably from salts of monoalkyl sulfates, each preferably having not more than 5 carbon atoms in the alkyl radical, and the corresponding acids, and more preferably selected from salts of methyl sulfate and / or ethyl sulfate and the corresponding acids.

3. The method according to one or both of the preceding claims, characterized

in that the aqueous composition (A) contains quaternary organic amines, which are preferably selected from heterocycles having at least one nitrogen heteroatom.

4. The method according to claim 3, characterized in that the heterocycle having at least one nitrogen heteroatom of the following structural formula (I):

with the radicals R ¹ , R ² and R ³ , each selected from hydrogen, branched or unbranched aliphatics having not more than 6 carbon atoms or the radical - (CR 4 R 4) x - [Z (R 4) (-i) - (CR 4 R 4 _y ] nZ (R4), where Z is selected from oxygen or nitrogen and p is Z in the case of nitrogen, takes the value 2 and otherwise equals 1, and x and y are natural numbers from 1 to 4 and n, respectively also is a natural number from 0 to 4 and R4 is selected from hydrogen or branched or unbranched aliphatics having not more than 6 carbon atoms, with the proviso that at least one of R ² or R ^{3 is} not selected from hydrogen;

Heterobrid atom selected from oxygen, nitrogen or sulfur

May be bridging atom and the carbon atoms in turn independently of each other with R ¹ radicals or such radicals substituted, via which a Anellierung of aromatic homocycles having not more than 6 carbon atoms is realized.

A method according to claim 4, characterized in that the

ring-constituting divalent radical Y is selected from ethylene, ethenediyl, 1,3-propanediyl, 1,3-propenediyl, 1,4-butanediyl, 1,4-butenediyl, 1,4-butadienediyl, -CH = N-, -CH 2 - NH, (N, N-dimethylene) amine, (N-methylene-N-methyllyliden) amine, preferably from ethenediyl, 1,4-butadienediyl, -C = N- or (N-methylene-N-methyllyliden) amine, particularly preferably from ethenediyl or -C = N- and particularly preferably from etendiyl, where in each case hydrogen covalently bonded to carbon atoms may be substituted by the other representatives of a radical R ¹ .

Method according to one or more of the preceding claims, characterized in that the quaternary organic amine is selected from 1, 2,3- Dimethyl imidazolium, 1-methyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-isopropyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1- (n-butyl) -3-methylimidazolium, 1- (isobutyl ) -3-methylimidazolium, 1-methoxy-3-methylimidazolium, 1-ethoxy-3-methylimidazolium, 1-propoxy-3-methylimidazolium, preferably from 1, 2,3-trimethylimidazolium.

7. The method according to one or more of the preceding claims, characterized

in that the proportion of conditioner calculated as the equivalent amount of SO ₄ , based in each case on the composition (A), is at least 0.05 g / kg, preferably at least 0.2 g / kg, particularly preferably at least 0.4 g / kg, however, preferably not greater than 5 g / kg, more preferably not greater than 3 g / kg.

8. The method according to one or more of the preceding claims, characterized

in that no conversion layer is produced on the surfaces of the metallic components in step i).

9. The method according to one or more of the preceding claims, characterized

in that the composition (B) in step ii) is at least 0.01 g / kg, preferably at least 0.05 g / kg, more preferably at least 0.1 g / kg, of water-soluble compounds of the elements Zr, Ti or Si contains the respective element.

10. The method according to one or more of the preceding claims, characterized

in that the composition (B) in step ii) is less than

0.05 g / kg, preferably less than 0.01 g / kg, more preferably less than 0.001 g / kg of free fluoride.

1 1. The method according to one or more of the preceding claims, characterized

in that the total fluoride content in the composition (B) in step ii) is less than 0.05 g / kg, preferably less than 0.01 g / kg, more preferably less than 0.001 g / kg, and more preferably less than 0.0001 g / kg.

12. The method according to one or more of the preceding claims, characterized

in that the composition (B) in step ii) additionally contains water-soluble compounds which are a source of copper ions, preferably in the form of water-soluble salts.

13. The method according to one or more of the preceding claims, characterized

characterized in that a rinsing step and preferably no drying step takes place between the method steps i) and ii).

14. The method according to one or more of the preceding claims, characterized

characterized in that the component at least partially surfaces of the materials iron and / or steel and preferably at least 50%, more preferably at least 80% of the surface of metallic materials of the component from surfaces of the materials iron and / or steel is formed.