EP3469115A1

EP3469115A1 - Method of cleaning pretreatment of ferrous components that have been joined by welding

Info

Publication number: EP3469115A1
Application number: EP17731096.8A
Authority: EP
Inventors: Christoph Sturm; Wilfried Serve; Stefan Dietz; Thomas JOHN-SCHILLINGS
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2016-06-10
Filing date: 2017-06-09
Publication date: 2019-04-17
Anticipated expiration: 2037-06-09
Also published as: WO2017212011A1; US11408080B2; US20190085469A1; JP6945562B2; EP3469115B1; JP2019517624A; CN109196142B; PL3469115T3; CN109196142A; CA3026786A1; DE102016210289A1; KR20190017921A; KR102317571B1

Abstract

The present invention relates to a method of cleaning pretreatment of ferrous components that have been joined by welding, in which residues from the welding operation are removed from the surface of the component and, in this way, subsequent wet-chemical conversion treatments are enabled so as to produce defect-free coatings. For cleaning pretreatment, the component is contacted with an aqueous sulfuric acid etchant which comprises amino alcohols, ethoxylates and/or propoxylates of fatty alcohols having 6 to 12 carbon atoms in the alcohol and iron ions, and is effective without the presence of fluorides. In a further aspect, the present invention encompasses an aqueous acidic etchant for cleaning pretreatment of ferrous components that have been joined by welding.

Description

Process for the purification pretreatment of iron-containing welds

components

The present invention relates to a method for cleaning pretreatment of iron-containing components joined together by welding in the residue from the

Welding process removed from the surface of the component and in this way subsequent wet chemical conversion treatments are made possible so that defect-free

Coatings are produced. For purifying pretreatment, the component is contacted with an aqueous sulfuric acid pickling containing aminoalcohols, ethoxylates and / or propoxylates of fatty alcohols having from 6 to 12 carbon atoms in the alcohol and iron ions, and effective without the presence of fluorides. In a further aspect, the present invention comprises an acidic aqueous pickle for the cleaning pretreatment of iron-bonded components assembled by welding.

Cleaning of metallic components is a necessary first process step in every wet-chemical industrial production stage in order to superficially remove the component from impurities from previous production stages and to adjust the surface for the subsequent finishing in such a way that reproducibly high-quality components result. Frequently, the components are already assembled from different materials or semi-finished products and have a correspondingly complex geometry. The object of the cleaning in a production stage for the wet-chemical pretreatment of a metallic component therefore consists primarily in the surface of auxiliaries such as drawing fats,

Corrosion protection oils to free machining fluids from the cutting or non-cutting shaping material processing or residues of joining processes and to set a uniform solely due to the chemical profile of properties of the metallic base substrate surface. For this purpose, depending on the manufacturing stage of the materials used and the superficial contamination with contaminants, a large number of water-based cleaners are generally commercially available, the effect of which is frequently based on removal of material by pickling, which is intensified by solubilizing the contaminants with the aid of surface-active substances. The acidic aqueous cleaners disclosed in WO2004 / 065661 are based on this principle for metallic components contaminated with forming aids which, in addition to an inorganic pH-adjusting builder, contain a mixture of nonionic surfactants based on ethoxylated aliphatic alcohols. Regardless of the multitude of available detergent formulations capable of specifically pickling metallic materials and in this way also eliminating surface contaminants, the cleaning of the surfaces of components is in the area of the welded connection of materials consisting of iron for the

Providing a temporary corrosion protection or a Lackhaftgrundes by way of a wet chemical conversion treatment, eg. The phosphating, problematic because in particular welding residues from slag-forming welding consumables with conventional cleaner formulations are insufficiently removed from the surface of the component. This is especially true for cleaner formulations that are largely free of fluorides and therefore for environmental health reasons are particularly desirable. Furthermore, there is a need in economic terms, the process temperatures during cleaning as low as possible and to keep the treatment times as short as possible. Such a performance spectrum can not currently be fully satisfied by commercial cleaner formulations for the cleansing pretreatment of components assembled by welding materials composed of iron.

The present invention meets this need and establishes a method for cleaning pretreatment of a component that is at least partially assembled by welding, wherein at least a part of the component, which is a material made of iron or steel, joined by the welding material fit with the rest of the component in which the component containing an aqueous fluoride-free sulfuric acid pickling

a) a total of at least 1 g / kg of amino alcohols;

b) a total of at least 0.5 g / kg of ethoxylates and / or propoxylates of

Fatty alcohols having 6 to 12 carbon atoms in the alcohol having at least 6 ethylene and / or propylene oxide units; and

c) iron ions

is brought into contact.

The term "welding" in the context of the present invention is the cohesive bonding of similar or dissimilar metals using heat or heat and pressure, as well as using welding consumables, which at least partially produce the cohesive connection.Welding consumables are usually in the form of coated metal wires or cored wires with core as well as in the form of powders used in combination with bare metal wires and have in addition to the function to support the material connection by gap bridging a protective function during welding, the therein there is a tendency to prevent scaling of the molten metal constituent of the filler metal and the materials to be joined in the welding area. The cladding, core or welding powder of the welding filler often consists of an inorganic, non-metallic material, which is used in the

Welding process, the weld and the solidifying melt completely encloses and protects in this way from the surrounding atmosphere. Welding processes according to the invention are all arc welding processes, in particular metal inert gas welding (MIG / MAG), tungsten inert gas welding (TIG) and spray arc welding, as well as laser and electron beam welding processes and combinations of these processes.

The cleaning of those parts of the component that are joined by welding, which are exposed to silicon due to the use of welding consumables, whether in the surface of the weld slag or in the molten metal wire, is particularly demanding for a subsequent wet chemical conversion treatment. In the method according to the invention, therefore, the component is joined in particular by welding which was carried out using silicon-containing welding additives. The silicon as a constituent of the welding filler material may be alloying constituent of the wire ("metal electrode"), chemical constituent of the respective slag-forming core or the sheath of the wire ("filler wire electrode" or "rod and wire electrodes") as well as of welding powder.

A cleaning pretreatment of a component which is at least partially joined together by welding, wherein by welding at least a part of the component, which is a material made of iron or steel, is integrally bonded to the rest of the component comprises according to the invention at least the contacting the region of this integral weld joint / s and of the immediately adjacent regions / s with the stain, preferably bringing the entire component into contact with the stain. One

coherent, the material connection by means of the molten

Welding ("welding") enclosing area is immediately adjacent to the cohesive welded joint, if in this the average hardness according to Vickers (VH) according to EN ISO 6507-1: 2005 measured with an indentor, which leaves no impression when properly measured, which is one dimension which exceeds the smallest extent of the weld, by more than 5% of that of the same material before

Welding deviates. The component which is pretreated by cleaning in the method according to the invention is preferably at least partially assembled from steel sheets, steel profiles and / or cast steel parts by welding.

Surprisingly, it has been shown that the residues of the welding filler material ("welding slag") can be effectively removed from the component by means of a sulfuric acid pickling based on a combination of amino alcohols and nonionic surfactants selected from fatty alcohols, without the additional presence of highly complexing fluorides, the be problematic for environmental health reasons,

must be resorted to.

According to the invention, a sulfuric acid pickling is distinguished by the fact that its pH is below 2.0, preferably below 1.0, and at least 20 g / kg of sulfuric acid,

preferably at least 40 g / kg sulfuric acid, calculated as SÜ4, the proportion of other acids having a pKsi value of less than 2.0 and their anions, based on the equivalent of sulfuric acid calculated as SO4, preferably less than 5 g / kg, in particular preferably less than 1 g / kg in total. In a preferred embodiment, the sulfuric acid pickle contains at least 60 g / kg, but for economic reasons preferably less than 120 g / kg, more preferably less than 90 g / kg of sulfuric acid calculated as

The sulfuric acid pickle used in the process according to the invention is also fluoride-free, which is to be equated with the fact that a total of less than 50 mg / kg, preferably less than 10 mg / kg, more preferably less than 1 mg / kg of fluoride ions are contained, wherein the proportion of fluoride ions in a TISAB buffered aliquot of the stain with a fluoride-sensitive electrode at 20 ° C is to determine (TISAB: "Total Lonic Strength Adjustment Buffer"), wherein the volume-related mixing ratio of buffer to the aliquot part of Pickling is 1: 1. The TISAB buffer is prepared by dissolving 58 g of NaCl, 1 g of sodium citrate and 50 ml of glacial acetic acid in 500 ml of deionized water (κ <Ι μβαττ ¹ ) and adjusting the pH to 5.3 by 5N NaOH and filling with a total volume of 1000 ml again with

deionized water (κ <Ι μβαττ ¹ ).

With regard to the amino alcohols according to component a) as an essential constituent of the pickling, in particular 1, 3-aminoalcohols and their ethylene or 1,2-propylene glycol monoethers, such as 2- (2-aminoethoxy) ethanol, 2- (2-aminoethoxy) propanol, proved effective, so that their use is preferred in the process according to the invention, with 1, 3-amino alcohols being particularly preferred. The 1, 3-amino alcohols are preferably selected from

Dimethylaminoethanol, diethylaminoethanol, N-methyldiethanolamine, mono-, di and / or

Triethanolamine and mono-, di- and triisopropanolamine. Particularly preferred in this context are mono-, di or triethanolamine and mixtures thereof. In this context, a stain has been found to be advantageous which contains both triethanolamine and monoethanolamine.

It is sufficient for pickling the components assembled by welding

According to the invention, it is preferred that the proportion of aminoalcohols, particularly preferably of 1,3-aminoalcohols, and their ethylene or 1,2-propylene glycol monoethers, particularly preferably of 1,3-aminoalcohols, is at least 2 g / kg, more preferably at least 4 g / kg However, for economic reasons, preferably 20 g / kg, more preferably 10 g / kg does not exceed. Particularly preferred are processes in which at least 80 wt .-%, preferably at least 90 wt .-% of all 1, 3-amino alcohols, preferably all 1, 3 amino alcohols and their ethylene or 1, 2-Propylenglykolmonoether, more preferably all amino alcohols in which pickling are selected from mono-, di and / or triethanolamine.

In the process according to the invention, the removal of the weld slag from the components to be cleaned furthermore requires the presence of the nonionic surfactant after component b) in the pickling.

For this purpose, it is advantageous if the nonionic surfactants have a specific HLB value, which promotes good wetting of the components and detachment and dispersion of the welding slag during the pickling process. In this respect, preference is given to processes in which the ethoxylates and / or propoxylates of the fatty alcohols according to component b) have an HLB value below 16, more preferably below 14, but preferably above 10. The HLB value ("Hydrophilic-Lipohilic Balance") is an empirical quantity and is calculated as follows:

HLB = 20 (1-M _L / M) with ML: molar mass of the nonionic surfactant's lipophilic group; M: molecular weight of the nonionic surfactant

In a preferred embodiment of the process according to the invention, the ethoxylates and / or propoxylates of fatty alcohols according to component b) are selected from ethoxylates, preferably from ethoxylates of fatty alcohols containing 8 to 10 ethylene oxide units and having 8 to 12 carbon atoms in the aliphatic radical of the fatty alcohol. In the method according to the invention is a proportion of ethoxylates and / or propoxylates of

Fatty alcohols according to component a) in the stain of at least 1 g / kg for a sufficient effect advantageous and therefore preferred. The proportion of fatty alcohols according to component b) in the mordant is particularly preferably at least 2 g / kg, but for economic reasons preferably not more than 10 g / kg, particularly preferably not more than 6 g / kg.

Further advantageous for the removal of the weld slag from the surfaces of the component, the simultaneous presence of such ethoxylates and / or propoxylates of

Beige fatty alcohols containing 6 to 12 carbon atoms in the fatty alcohol and less than 6 ethylene and / or propylene oxide units. Such stains are therefore in

Preferably used according to the invention method, wherein their mass-related proportion relative to the proportion of component b) is preferably in the range of 1:10 to 4: 10.

The presence of iron ions in the stain is also required in inventive process for a supporting pickling attack on the component and thus successful release of the component of welding slag in economic periods. Accordingly, preference is given to processes according to the invention which contain at least 10 g / kg of iron ions in the mordant. On the other hand, precipitations of iron (III) hydroxides on the surfaces of the component during pickling should be avoided so that according to the invention preferably not more than 70 g / kg, more preferably not more than 50 g / kg, of iron ions are contained in the mordant should.

Water-soluble salts, preferably water-soluble salts of iron (II) ions, particularly preferably iron (II) sulfate, serve as source of iron ions. Alternatively, iron powder of a sulfuric acid pickling containing the components a) and b) can be added and in this way an amount of iron ions are released. If necessary, the pH value of the sulfuric acid pickling has to be readjusted in the latter case due to the acid consumption.

Furthermore, it is preferred that the component undergoes no pre-passivation of the metal surfaces during the pickling process in the process according to the invention and the surfaces of the cleaned and virtually blank metallic surfaces of the component are subsequently subjected to a wet-chemical conversion treatment. In a preferred process according to the invention, therefore, less than 1 g / kg, preferably less than 0.1 g / kg, particularly preferably less than 0.01 g / kg, of dissolved phosphates is calculated in the stain as PO4. For the same reason, in the stain preferably less than 0.01 g / kg in total, especially preferably less than 0.001 g / kg of water-soluble compounds of the elements Zr and / or Ti based on the respective element.

It is preferred for complete removal of organic surface contaminants when the stain in the process of the invention precedes alkaline degreasing of the component, more preferably immediately preceded by an intermediate rinse step, wherein the alkaline degreasing is at a pH of at least 10.

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 cleaned, which are removed from a previous wet-chemical treatment step, for example, the alkaline degreasing, with the adhering to the component wet film, by means of a water-based liquid medium , The water-based liquid medium contains no chemical components that cause a significant surface coverage of the components made of metallic materials with subgroup elements, semi-metal elements or polymeric organic compounds. Such a significant

Surface coverage would in any case occur if the liquid medium of the sink at least 10 milligrams per square meter of the rinsed surfaces, preferably by at least 1 milligram per square meter of the rinsed surfaces of these components based on the respective element or the respective polymeric organic compound depleted, without Gains due to carryover and losses due to extraction of wet films adhering to the component.

As already mentioned in the context of the present invention and also discussed in connection with the problem area underlying the invention, the cleaning pretreatment of the component serves in particular the preparation of the same for a wet-chemical

Conversion treatment, in the course of which as passivating as possible, the

Paint adhesion-improving layer on the surfaces of the component and there is produced in particular on the contaminated with welding slag areas. Therefore, according to the invention, those methods are preferred in which the pickling is followed by a wet chemical conversion treatment of the component, again preferably directly with or without intermediate rinsing and / or drying step, particularly preferably without intervening drying step.

A drying step according to the invention is any method step in which by the

Provision and use of technical means a drying of the aqueous, on the surface the liquid film adhered by welding is intended, in particular by supplying thermal energy or impressing an air flow.

Wet-chemical conversion treatment according to the invention is understood as meaning the contacting of at least the iron or steel surfaces of the component with an aqueous one

Composition that is a passivating and essentially inorganic

Conversion coating produced on the surfaces of the treated iron or steel materials. In this case, a conversion coating is any inorganic coating on the iron or steel surfaces of the component which does not represent an oxide or hydroxide coating whose cationogenic main constituent is iron ions. A conversion coating may therefore be an iron phosphate layer.

According to the invention, the wet-chemical conversion treatment is preferred by means of acidic aqueous compositions whose pH is above 1 but below 5, and which preferably represents a layer-forming phosphating. A layer-forming

According to the invention, phosphating represents a phosphating which effects a coating layer calculated as PO4 of at least 0.5 g / m ² . Such phosphations are the

Person skilled in the surface treatment notoriously known, for example as zinc phosphating or so-called Trikationphosphatierung.

A wet-chemical conversion treatment described above follows again

According to the invention preferably with or without intervening rinsing and / or

Drying step, preferably without intervening drying step, a

Dip coating of the component, preferably an electrocoating.

In a further aspect, the present invention comprises an acidic aqueous pickling, which is particularly suitable for use in the method according to the invention for the cleansing pretreatment of components which have welded connections of material made of iron and / or steel produced by welding.

Such mordants according to the invention have a pH below 2.0 and contain i) 40 to 120 g / kg, preferably 60 to 90 g / kg of sulfuric acid calculated as SO4;

ii) 2 to 20 g / kg, preferably 4 to 10 g / kg of amino alcohols; iii) 0.5 to 5 g / kg, preferably 1 to 3 g / kg of ethoxylates and / or propoxylates of fatty alcohols having 6 to 12 carbon atoms in the alcohol having at least 6 ethylene and / or propylene oxide units; iv) 10 to 50 g / kg of iron ions;

v) less than 50 mg / kg, preferably less than 10 mg / kg, more preferably

less than 1 mg / kg of fluoride ions;

vi) less than 1 g / kg, preferably less than 0, 1 g / kg, more preferably

less than 0.01 g / kg of dissolved phosphates calculated as PO4.

The already mentioned in the context of the process according to the invention with respect to the preferred chemical-structural embodiments of components a) to c) of sulfuric acid pickling also represent preferred embodiments of components ii) to iv) of the acidic aqueous pickling according to the invention.

In a preferred embodiment, in the stain according to the invention as component vii) additionally 0.5 to 5 g / kg, preferably 1 to 3 g / kg of ethoxylates and / or propoxylates of fatty alcohols having 6 to 12 carbon atoms in the alcohol with less than 6 Contain ethylene and / or propylene oxide units.

Preferably, an acidic aqueous pickling according to the invention contains less than 1% by weight, preferably less than 0.1% by weight, of components which are not components i) to vi).

EXAMPLES

Test parts assembled from two cut steel sheets (200 × 200 × 2 mm) by means of metal active gas welding (mixed gas M20: 90% argon, 10% CO 2) were treated according to the process steps defined below. Welding was carried out according to AWS A 5.28 / A 5.28M: 2007 using a slag-forming silicon-containing filler metal. The weld bead had a length of about 100 mm and a width of about 2-3 mm.

A. Alkaline degreasing:

Immersing the test piece in a mixture of Bonderite® C-AD 1563 (3% by weight) and

Bonderite® C-AD 1400 (0.3 wt%) at 65 ° C for 10 minutes

B. Acid stain:

B.1 Immersion at 60 ° C for 4 minutes in sulfuric acid pickling

b) 1, 5 g / kg ethoxylated (8EO) fatty alcohol (C10) c) 20 g / kg iron (II) sulfate

d) 0.45 g / kg ethoxylated (4EO) fatty alcohol (C8)

B.2 Immersion of the test piece at 60 ° C for 15 minutes in mixed acid pickling containing

c) 40 g / kg of iron (II) sulfate

d) 1, 8 g / kg of ammonium bifluoride

C. Zinc phosphating:

Immersion of the test piece in Bonderite® M-ZN 958 at 52 ° C for 4 minutes, the

Test section immediately before but with intermediate rinsing step with deionized water (κ <1 μβαττ ¹ ) was activated with Bonderite® M-AC 950 at 25 ° C for 1 minute.

In a process sequence AB.1 -C according to the invention, a metallically lustrous surface was obtained in the region of the weld seam. Only under the light microscope were in this area to detect minimal residues of welding slag. Scanning electron micrographs (SEM) confirm the overall good optical result and demonstrate by means of energy dispersive X-ray spectroscopy (EDX) that only small amounts of silicon can be detected in some areas.

In contrast, despite the tripled treatment time in a conventional process sequence A-B.2-C with a fluoride-containing mixed acid pickle already with the naked eye residues of

Welding slag recognizable as matt areas. Light microscopic and SEM images confirmed this. In addition, no zinc phosphate layer was formed on the areas where, prior to and immediately after the pickling, residues of the weld slag were identified with the naked eye.

Claims

Expectations

1. A method for the cleaning pretreatment of a component that is at least partially assembled by welding, wherein at least part of the component, which is a material made of iron or steel, is cohesively connected to the remaining component by the welding, characterized in that the component with an aqueous fluoride-free sulfuric acid stain

a) a total of at least 1 g/kg of amino alcohols; b) a total of at least 0.5 g/kg of ethoxylates and/or propoxylates

fatty alcohols with 6 to 12 carbon atoms in the alcohol with at least 6 ethylene and / or propylene oxide units; and c) iron ions

is brought into contact.

2. The method according to claim 1, characterized in that the amino alcohols according to

Component a) is selected from 1,3-amino alcohols and their ethylene or 1,2-propylene glycol monoethers, preferably from 1,3-amino alcohols, particularly preferably from mono-, di- and/or triethanolamine.

3. Method according to one or more of the preceding claims, characterized in that the proportion of amino alcohols is at least 2 g/kg, preferably at least 4 g/kg, but preferably does not exceed 20 g/kg, particularly preferably 10 g/kg.

4. The method according to one or more of the preceding claims, characterized in that the ethoxylates and / or propoxylates of the fatty alcohols according to component b) have an HLB value below 16, preferably below 14, but preferably above 10.

5. The method according to one or more of the preceding claims, characterized in that the ethoxylates and / or propoxylates of the fatty alcohols according to component b) are selected from ethoxylates, preferably from ethoxylates of fatty alcohols with 8 to 12

Carbon atoms in the alcohol with 8 to 10 ethylene oxide units.

6. The method according to one or more of the preceding claims, characterized in that the proportion of ethoxylates and / or propoxylates of fatty alcohols according to component b) in the stain is at least 1 g / kg, preferably at least 2 g / kg, but preferably not greater than 10 g/kg, particularly preferably not greater than 6 g/kg.

7. The method according to one or more of the preceding claims, characterized in that the pickle additionally contains ethoxylates and/or propoxylates of fatty alcohols with 6 to 12 carbon atoms in the alcohol with less than 6 ethylene and/or propylene oxide units.

8. The method according to one or more of the preceding claims, characterized in that in the stain at least 10 g / kg, but preferably not more than 70 g / kg, particularly preferably not more than 50 g / kg of iron ions according to component c ) are included.

9. The method according to one or more of the preceding claims, characterized in that the stain contains a total of less than 1 g/kg, preferably less than 0.1 g/kg, particularly preferably less than 0.01 g/kg of dissolved phosphates calculated as contains PO4.

10. The method according to one or more of the preceding claims, characterized in that the stain is preceded by an alkaline degreasing of the component, preferably immediately preceded by an intermediate rinsing step, the alkaline degreasing taking place at a pH of at least 10.

1 1 . Method according to one or more of the preceding claims, characterized in that the stain is followed by a wet chemical conversion treatment of the component, preferably immediately with or without intermediate rinsing and/or

Drying step, particularly preferably without an intermediate drying step.

12. The method according to claim 1 1, characterized in that the wet chemical

Conversion treatment takes place using acidic aqueous compositions whose pH is above 1 but below 5, and preferably a layer-forming one

represents phosphating.

13. Containing acidic aqueous stain with a pH value below 2.0 i) 40 to 120 g/kg, preferably 60 to 90 g/kg of sulfuric acid calculated as SC; ii) 2 to 20 g/kg, preferably 4 to 10 g/kg of amino alcohols;

iii) 0.5 to 5 g/kg, preferably 1 to 3 g/kg of ethoxylates and/or propoxylates of fatty alcohols with 6 to 12 carbon atoms in the alcohol with at least 6 ethylene and/or propylene oxide units; iv) 10 to 50 g/kg of iron ions;

v) less than 50 mg/kg, preferably less than 10 mg/kg, particularly preferably less than 1 mg/kg of fluoride ions;

vi) less than 1 g/kg, preferably less than 0.1 g/kg, particularly preferably less than 0.01 g/kg of dissolved phosphates calculated as PO4.

14. Stain according to claim 13, characterized in that as component vii) additionally 0.5 to 5 g / kg, preferably 1 to 3 g / kg of ethoxylates and / or propoxylates of fatty alcohols with 6 to 12 carbon atoms in the alcohol with less than 6 ethylene and/or

Propylene oxide units are contained.