EP3230491A1

EP3230491A1 - Integration of light metals into steel pickling and pretreating processes

Info

Publication number: EP3230491A1
Application number: EP15804762.1A
Authority: EP
Inventors: Andreas Richard BENDER
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2014-12-09
Filing date: 2015-12-03
Publication date: 2017-10-18
Anticipated expiration: 2035-12-03
Also published as: EP3230491B1; WO2016091703A1; ES2718759T3; DE102014225237B3

Abstract

The present invention concerns a method for wet-chemically pretreating a multiplicity of iron components and a multiplicity of aluminium components in series, with each of the iron components undergoing in immediate succession first a pickle (1) and then a reactive rinse (2), and with each of the aluminium components likewise undergoing this same reactive rinse (2), but without having undergone a pickle (1), the pickle (1) being effected by contacting the components with an aqueous bath solution (A) which is acidified with sulphuric acid and has a pH of below 1.0, and the reactive rinse (2) being effected by contacting the components with an aqueous bath solution (B) which is acidified with sulphuric acid and contains a total of at least 0.02 g/kg of water-soluble compounds of the elements Zr and/or Ti, based in each case on the respective elements, and has a pH of not below 1.0.

Description

"Picking up of light metals in pickling and pretreatment processes for steel"

The present invention relates to a process for wet-chemical pretreatment of a plurality of iron components and a plurality of aluminum components in series.

For various industries, such as the agricultural industry, iron components, especially steel components, processed and manufactured. During manufacture, these components are pickled and applied a conversion layer. For this purpose, the components undergo established production lines with a specific sequence of different immersion baths, which are adapted to the chemical composition of the iron components. To save weight, however, more and more iron components are replaced by components made of light metal such as aluminum or magnesium. However, the production lines designed for iron components can not pass through light metals such as aluminum or magnesium because of their properties other than iron. Thus, certain dipping baths, which are integrated into production lines for iron components and adapted to these components, a very low pH (pH <1), so that when passing through such baths, the etching of the light metal components is too large. So that production lines designed for iron components can also be run through by light metal components, in the prior art further immersion baths are integrated into the already existing production lines. Alternatively, separate production lines are also newly built, which are used only for the processing and production of light metal components. However, this is associated with additional costs and effort and thus unfavorable. Therefore, there is a need for a process for wet-chemical pretreatment of a plurality of iron components and a plurality of aluminum components in series, which can be carried out in a production line.

It has now surprisingly been found that a plurality of iron components and a plurality of aluminum components can be wet-chemically pre-treated in series by each of the iron components immediately successively first a pickling (1) and then a reaction rinse (2) passes through, and by each of the aluminum components also the same reaction rinse (2) passes through, but without having a stain (1) to go through. Thus, without rebuilding the manufacturing plant or providing additional immersion baths, established production lines for iron components can be used both for iron components and for components made of light metal such as aluminum or magnesium. Therefore, in a first aspect, the invention relates in a first aspect to a process for the wet-chemical pretreatment of a plurality of iron components and a plurality of aluminum components in series, in which each of the iron components passes through first a pickle (1) and subsequently a reaction nozzle (2), successively each of the aluminum components also undergoes the same reaction rinse (2) but without having undergone a pickle (1), the method being characterized in that the pickle (1) is contacted by contacting with a sulfuric acid aqueous bath solution (A) a pH below 1, 0 and the reaction rinse (2) by contacting with a sulfuric acid aqueous bath solution (B), the total of at least 0.02 g / kg of water-soluble compounds of the elements zirconium and / or titanium, respectively based on the respective elements and their pH is not less than 1, 0 takes place.

It has now surprisingly been found that by the method according to the invention, a plurality of iron components and a plurality of light metal components, in particular aluminum and magnesium components, can be treated wet-chemically in series, without the treatment and production of these components interfere with each other. In this case, already established iron-component-oriented production lines can be used, without the need for reconfiguration of these lines, additional immersion baths and / or process steps. Further, from each iron member, a small portion of the aqueous bath solution (A) containing iron ions by the pickling operation of the iron members is entrained into the bath solution (B). The entrained bath solution (A) and the iron ions contained therein have an advantageous effect on the reaction rinse (2), since the iron ions accelerate the formation of the conversion layer on the light metal components and the bath solution (A) the bath solution (B) also acidified, ie an advantageous pH in the bath solution (B) can keep constant or at least contributes to the maintenance of the advantageous pH, but this does not fall below a value of 1, 0. It has surprisingly been found that a relatively high content of iron ions in the bath solution (B) of up to 10 g per kg bath solution (B) has no negative effect on the bath solution (B) or on the formation of the conversion layer on the light metal components ,

The pretreatment according to the invention serves to apply a corrosion-protecting first coating as a primer for organic coatings. The pretreatment therefore always ends with the application of a first organic coating (primer, dip paint, powder coating), which itself is not a pretreatment step in the sense of the present invention.

A "variety" as used herein refers to 2 or more, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 200, 300, 400 or more. The inventive method relates to a wet chemical pretreatment of a plurality of iron components and a plurality of aluminum components in series. According to the invention, pretreatment in series is the bringing into contact of a large number of components with bath solutions stored in system tanks for pickle (1) and / or reaction blister (2) and / or further wet chemical treatment steps, wherein the individual components are brought into contact one after the other and thus separated in time.

As used herein, "wet-chemical" describes that a change in the chemical finish of at least one of the metallic surfaces of the component to be treated is effected by contact with a liquid, which liquid is usually substantially water then "wet-chemically", if during its course at least one contacted with the liquid, metallic surfaces undergoes a pickling of at least 0.5 g / m ² or the liquid at least 10 g / kg of organic compounds having a molecular weight of at least 100 g contains / mol or a significant surface coverage is effected with metallic or semi-metallic foreign elements. Foreign elements in this context are metallic or semi-metallic elements whose surface portion in the contact area of the component with the liquid immediately before contacting is less than 5 At .-% measured by X-ray photoelectron spectroscopy (Al-α radiation and 54.7 ° angle between the beam incidence and the detector A significant surface coverage is in any case present if the proportion of metallic or semi-metallic foreign elements on at least one metallic surface of the component immediately after the treatment step is greater than 1 mg / m ² based on the respective foreign element Pickling (1) or reaction (2) are therefore typical wet-chemical treatment steps as well as activation (3) and phosphating (4).

The iron components used according to the method essentially have surfaces of steel and / or iron, preferably more than 60%, particularly preferably more than 80%, particularly preferably more than 90% of all metallic surfaces of the iron components are surfaces of steel and / or iron. In a particularly preferred embodiment of the method according to the invention, all metallic surfaces of the iron components are surfaces of steel and / or iron. The iron component may optionally contain additives of other metals and / or non-metals. These additives may be selected from the group comprising carbon, silicon, chromium, nickel, manganese, molybdenum, tungsten, and mixtures of the foregoing, but the group is not limited thereto.

Aluminum members as used herein have substantially surfaces of aluminum and / or aluminum alloys, preferably more than 60%, more preferably more than 80%, most preferably more than 90% of all metallic surfaces of the Aluminum components Surfaces of aluminum and / or its alloys. In a particularly preferred embodiment of the method according to the invention, all metallic surfaces of the aluminum components are surfaces of aluminum and / or its alloys. The aluminum components may optionally include additives of other metals and / or non-metals. Such additives may be selected from the group comprising silicon, beryllium, magnesium, copper, nickel, zinc, manganese and mixtures of the foregoing, but the group is not limited thereto.

In the pretreatment according to the invention, each of the iron components passes immediately after a pickle (1) and then a reaction rinse (2), whereas each of the aluminum components through the same reaction rinse (2), but without having the stain (1) to go through.

Process steps for a component in the context of serial pretreatment then follow each other "directly" if they are not interrupted by another than the respectively provided subsequent wet-chemical treatment or a rinsing step.

The stain (1) is made by contacting the iron component with a sulfuric acid bath solution (A) having a pH below 1, 0. Preferably, the pH is in the range of 0 to <1. The bath solution (A) contains water as the main component and sulfuric acid to adjust the desired pH.

The "pH" as used herein corresponds to the negative decadic logarithm of the hydronium ion activity at 20 ° C and can be determined by pH-sensitive glass electrodes.

In this pickling step, the plurality of iron components is pickled, wherein on the surface of the component iron in the form of iron ions goes into solution. In a preferred embodiment of the method according to the invention, the bath solution (A) of the stain (1) has a free acid content in points of at least 50, more preferably of at least 130 to 200, but preferably of not more than 400.

The "free acidity" in points is determined in accordance with the consumption of 0.1 N sodium hydroxide solution in milliliters until a pH of 4.0 at a withdrawn volume of the respective bath solution of 10 ml and a dilution in the ratio of 1: 5 ,

In a preferred embodiment of the present invention, the stain (1) contains not more than 80 g / kg, preferably not more than 60 g / kg of iron ions, but preferably at least 1.0 g / kg of iron ions in each case based on the bath solution (A). The reaction rinse (2) is carried out by bringing the component into contact with a sulfuric acid bath solution (B). Bath solution (B) has a pH not lower than 1.0. Preferably, the bath solution (B) has a pH of less than 2.5, and more preferably less than 1.8. The preferred pH range of bath solution (B) is thus 1.0 to <1.8. The main component of bath solution (B) is water. The desired pH of the bath solution (B) can be adjusted with the aid of acids, in particular a mixture of sulfuric acid and hydrofluoric acid. In various embodiments, this mixture may comprise at least 0.5% by weight, particularly preferably at least 1% by weight, of sulfuric acid and 1 to 200 ppm, preferably 5 to 50 ppm of hydrofluoric acid.

But it is also possible that the adjustment of the pH of the bath solution (B) of the reaction rinse (2) by the entrained by the iron components bath solution (A). This is advantageous because the iron ions which are produced in the bath solution (A) by the pickling and then transferred into the bath solution (B) by means of the iron components accelerate the formation of the conversion layer on the light metal components. Further, by entraining the bath solution (A) into the bath solution (B), the pH of the bath solution (B) is kept constant in the desired range over a long period of time during the process without the addition of acids being required.

But it is also possible to adjust the pH of the bath solution (B) both by the addition of sulfuric acid or mixtures, which - as described above - sulfuric acid and hydrofluoric acid, as well as by the entrained bath solution (A) or constantly to hold. The bath solution (B) of the reaction bowl (2) preferably contains a free acid content in points of at least 3, more preferably of at least 10, but preferably of not more than 30.

In various embodiments, the reaction rinse (2) additionally contains iron ions in an amount of at least 0.1 g / kg, in particular at least 1 g / kg, but preferably not more than 10 g / kg, more preferably not more than 6 g / kg in each case based on the bath solution (B).

The bath solution (B) further comprises a total of at least 0.02 g / kg of water-soluble compounds of the elements zirconium and / or titanium in each case based on the respective elements. In various embodiments, the reaction rinse (2) comprises a total of less than 1 g / kg, preferably less than 0.6 g / kg, more preferably less than 0.3 g / kg, but preferably at least 0.1 g / kg, more preferably at least 0.2 g / kg of water-soluble compounds of the elements zirconium and / or titanium in each case based on the respective elements. The water-soluble compounds may be any of the water-soluble compounds of these metals known in the art and suitable for this purpose. For the purposes of the present invention, compounds are "water-soluble" if their solubility in deionized water having a conductivity of not more than 1 μ8ϋΐη ^~1 at a temperature of 20 ° C. is at least 1 g / l.

The water-soluble titanium compounds which can be used according to the invention include in particular salts and esters of titanic acid, the so-called titanates. For example, hUTiC and the corresponding alkoxides such as tetraethyl titanate can be used for this purpose. Furthermore, the titanium (IV) and titanium (l l l) halides such as TiC and TiCU can be used. In particular, the hexafluoroacids of the titan H2T1F6 and their water-soluble salts can be used, such as (NhU ^ TiFe, Li2TiF6, K2T1F6 and Na2TiF6.

As water-soluble compounds of zirconium, (NH4) 2Zr (C03) 2 (OH) 2, zirconium acetates, zirconium halides such as ZrCu and hexafluorozirconic acid and their salts such as (NH4) 2ZrF6, Li2ZrF6, 2ZrF6 and Na2ZrF6 can be used. In particular, F ZrFe and its water-soluble salts are suitable.

It is generally preferred for rapid conversion of the metal surfaces of the components that the bath solution (B) have a minimum level of free fluoride of 5 ppm.

Furthermore, it is generally advantageous if the bath solution (B) has an aluminum content of less than 5 g / l. Should this value be reached or exceeded, it may be necessary to lower the aluminum content, for example by partial or complete replacement of the bath solution.

The "bringing into contact" of the components with the respective bath solutions in the method according to the invention comprises any such time-limited technical measure on the basis of which the components are wetted with the respective bath solution Coating with the respective bath solution, but are not limited to these possibilities.

The bringing into contact of the plurality of iron or aluminum components with the bath solutions in the pickling (1) and / or the reaction rinse (2) can be carried out over a period of 0.01 min to 10 min, preferably 0.05 min to 5 minutes, more preferably from 0.25 minutes to 3 minutes.

Further, contacting may occur at an elevated temperature of the respective bath solution (s). In various embodiments, the contacting is carried out at elevated temperature of the bath solutions (A) and (B). For example, bringing into contact with the Pickling (1) and / or the reaction rinse (2) at a temperature of 5 ° C to 95 ° C. In a preferred embodiment, the contacting is carried out at a temperature of from 5 ° C to 90 ° C, preferably from 10 ° C to 65 ° C, more preferably from 15 ° C to 40 ° C, and most preferably at 20 ° C up to 30 ° C performed. In this case, it is possible for the stain (1) and the reaction bowl (2) to be carried out at different temperatures for different lengths of time depending on the respective component, such as composition and size of the surface, and the bath solutions (A) and (B) ,

If according to the invention it is provided that the aluminum components "pass through the same reaction bowl (2)", this means that during the period within which an iron component is just and the aluminum component immediately following in the series treatment just does not react with the bath solution of the reaction bowl (2 ) is brought into contact, preferably during a period within which a component just and a component immediately following in the series treatment is just not brought into contact with the bath solution of the reaction rinse (2), the bath solution of the reaction rinse (2) is not complete is exchanged.

Optionally, the method according to the invention may comprise further steps. In a preferred embodiment, the plurality of iron components after the reaction column (2) undergo a wet chemical conversion layer formation, for example on the basis of the same water-soluble compounds as used in the reaction column (2), but at a pH in the range of 2.5. 4,0, or based on a phosphating. According to the invention, the plurality of iron components after the reaction rinse (2) preferably undergo activation (3) followed by phosphating (4). The phosphating (4) is preferably a zinc phosphating. Activation (3), phosphating (4) and zinc phosphating are well established in the art and can be carried out by known methods and chemicals.

Activation (3) increases the number of phosphate crystals growing per unit of metal surface during phosphating. Furthermore, the sizes of the single crystals in the final phosphate layer are in some cases considerably reduced, the basis weight of the phosphate layer is reduced, and the time required to cover the metal surface with phosphate crystals is shortened. The activation additionally fixes crystal nuclei on the metal surface, which serve as phosphate nucleation points. The activation may be carried out by any methods and chemicals known in the art and suitable for this purpose. Thus, in the case of zinc phosphating, the iron component may be treated with a dispersion of titanium phosphate, tertiary zinc phosphate and / or tertiary iron (II) zinc phosphate. The phosphating (4) can be carried out with the aid of a phosphate-containing solution. The provision of the phosphate-containing solution can be carried out by adding, for example, phosphoric acid and / or salts of phosphoric acid, such as NasPC, K3PO4, Ca3 (PO4) 2 or mixtures thereof to water or an aqueous solution. If the phosphating (4) is a zinc phosphating, the phosphate-containing solution further contains zinc ions. Further, other known in the art agents such as accelerators and heavy metal cations selected from manganese, copper, nickel and / or cobalt ions can be added.

In a preferred embodiment of the present invention, the aluminum parts after the reaction rinse (2) do not undergo the phosphating (4), preferably neither the activation (3) nor the phosphating (4), particularly preferably no phosphating, and in particular preferably no further wet-chemical pretreatment but preferably at least one, preferably two rinse steps. A "rinsing step", as used in the context of the invention, is not a wet chemical treatment step and serves solely to completely or partially remove water soluble residues, particles and kneading components adhered to the component from a previous wet chemical treatment step, without the component to be treated In this context, "active components" are understood to mean exclusively components which have a significant surface coverage of the components with metallic or semi-metallic foreign elements, ie elements whose surface portion in the contact region of the component with the the active component contained liquid immediately before contacting less than 5 at .-% measured by X-ray photoelectron spectroscopy is (Al-Κα radiation and 54.7 ° angle between S trap incidence and detector), or cause organic compounds and thereby consume. A significant surface coverage is in any case when the proportion of metallic or semi-metallic foreign elements on the surfaces of the component immediately after the treatment step is on average greater than 1 mg / m ² based on the foreign element.

In a further preferred embodiment of the present invention, the aluminum and iron components before the reaction rinse (2) undergo an alkaline degreasing and cleaning. In this case, the aluminum and iron components preferably undergo the same alkaline degreasing and cleaning, whereby the iron components always undergo said degreasing and cleaning before the stain (1). This alkaline degreasing and cleaning can be carried out using any degreasing and cleaning method known in the art and suitable for this purpose. These include, but are not limited to, the treatment with solutions containing agents selected from the group of surfactant-active substances and soaps Group are limited. Alternatively, organic solvents, such as. As alcohols, are used for degreasing and cleaning.

In another embodiment of the invention, in addition, a plurality of magnesium components are treated in series, wherein each of the magnesium components also the same reaction rinse (2) as the iron and aluminum components passes through, but without having a stain (1) to go through.

"Magnesium components" have substantially surfaces of magnesium and / or magnesium alloys, preferably more than 60%, more preferably more than 80%, most preferably more than 90% of all metallic surfaces of the magnesium components surfaces of magnesium and / or its alloys.

In a particularly preferred embodiment of the method according to the invention, all metallic surfaces of the magnesium components are surfaces of magnesium and / or its alloys.

Since magnesium or magnesium alloys are more reactive than aluminum or aluminum alloys, it may be advantageous for the bath solution (B) of the reaction bowl (2) to have a slightly higher pH than the values indicated above as preferred, for example in the range from 2 to 2.5. The period and temperature of the reaction bowl (2), as indicated above for the iron and aluminum components, are transferable to the magnesium components which are subjected to the reaction bowl (2).

Furthermore, for the plurality of magnesium components, a method is preferred in which the same undergo no further wet chemical pretreatment, which is a phosphating, preferably no further wet chemical pretreatment, but preferably at least one, more preferably at least two rinsing steps.

In various embodiments, it may be advantageous that all wet-chemical treatment steps that a component according to the invention, although successively, but not immediately successive, are interrupted by intervening rinsing steps. A rinsing step in the context of the present invention, as previously defined, is not a wet-chemical treatment step and serves solely to completely or even partially remove the agent with which the component has previously been treated. Such rinsing steps are known in principle in the prior art. The rinsing step can be adapted to the rinsing step performed before and after. Thus, for example, such a rinsing step with water without additives optionally be carried out at elevated temperature. It can do that Water but also additives, such as acids, alkalis, washing-active substances or soaps are added. Further, the components may also be cleaned by means of organic solvents such as alcohols or organic solvent mixtures. The rinsing step may be accomplished by contacting as defined herein.

Claims

Claims:

A process for the wet-chemical pretreatment of a plurality of iron components and a plurality of aluminum components in series, in which each of the iron components passes through a pickle (1) and subsequently a reaction rinse (2) in direct succession, and in which each of the aluminum components also has the same reaction rinse ( 2), but without having undergone a stain (1), characterized in that the stain (1) by contacting with a sulfuric acid aqueous bath solution (A) having a pH below 1, 0 and the Reaction rinse (2)

In contact with a sulfuric acid aqueous bath solution (B) containing a total of at least 0.02 g / kg of water-soluble compounds of the elements Zr and / or Ti, based in each case on the respective elements and their pH not less than 1, 0 is, takes place.

2. The method according to claim 1, characterized in that the bath solution (A) of the stain (1) has a free acid content in points of at least 50, more preferably of at least 130-200, but preferably of not more than 400.

3. The method according to one or both of the preceding claims, characterized in that the stain (1) not more than 80 g / kg, preferably not more than 60 g / kg of iron ions, but preferably at least 1, 0 g / kg to iron ions in each case based on the bath solution (A) contains.

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

in that the bath solution (B) of the reaction bowl (2) has a free acid content in points of at least 3, particularly preferably at least 10, but preferably not more than 30.

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

in that the bath solution (B) of the reaction bowl (2) has a pH above 1, 0, but preferably below 2.5, particularly preferably below 1.8.

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

characterized in that in the reaction rinse (2) a total of less than 1 g / kg, preferably less than 0.6 g / kg, more preferably less than 0.3 g / kg, but preferably at least 0.1 g / kg, particularly preferred at least 0.2 g / kg water-soluble compounds of the elements Zr and / or Ti in each case based on the respective elements and the bath solution (B) are included.

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

characterized in that in the reaction rinse (2) additionally iron ions in an amount of at least 0, 1 g / kg, preferably of at least 1 g / kg, but preferably not more than 10 g / kg, more preferably not more than 6 g / kg of iron ions in each case based on the bath solution (B) are included.

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

characterized in that the iron components after the reaction rinse (2) undergo an activation (3) followed by a phosphating (4), which is preferably a zinc phosphating.

9. The method according to claim 8, characterized in that the aluminum parts after the reaction rinse (2) not the phosphating (4), preferably neither the activation (3) nor the phosphating (4), but preferably at least one, preferably two rinsing steps.

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

characterized in that the aluminum components after the reaction rinse (2) undergo no further wet-chemical pretreatment, but preferably at least one, preferably two rinsing steps.

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

characterized in that the aluminum and iron components before the reaction rinse (2) undergo an alkaline degreasing and cleaning, preferably the same alkaline degreasing and cleaning, the iron components always undergo this alkaline degreasing and cleaning before the stain (1).

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

characterized in that in addition a plurality of magnesium components is treated in series, wherein each of the magnesium components also through the same reaction rinse (2) as the iron and aluminum components, but without having a stain (1) to go through.

13. The method according to claim 12, characterized in that the magnesium components after the reaction rinse (2) undergo no further wet chemical pretreatment, the one Phosphatization is, preferably no further wet-chemical pretreatment, but preferably at least one, more preferably at least two rinsing steps.

Method according to one or more of the preceding claims, characterized

in that all wet-chemical treatment steps which a component according to the invention, although successively, but not immediately successive, are interrupted by intervening rinsing steps.