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WO2025195866A1 - Procédé de nettoyage et de dégraissage de composants comprenant des surfaces d'acier galvanisées à chaud par immersion dans du zinc-magnésium - Google Patents

Procédé de nettoyage et de dégraissage de composants comprenant des surfaces d'acier galvanisées à chaud par immersion dans du zinc-magnésium

Info

Publication number
WO2025195866A1
WO2025195866A1 PCT/EP2025/056722 EP2025056722W WO2025195866A1 WO 2025195866 A1 WO2025195866 A1 WO 2025195866A1 EP 2025056722 W EP2025056722 W EP 2025056722W WO 2025195866 A1 WO2025195866 A1 WO 2025195866A1
Authority
WO
WIPO (PCT)
Prior art keywords
mmol
cleaner
zinc
aqueous
dissolved
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/056722
Other languages
German (de)
English (en)
Inventor
Nadine Isabel Millies
Kristof WAPNER
Jan-Willem Brouwer
Christina ANGENENDT
Andreas Arnold
Fernando Jose RESANO ARTALEJO
Christian KOLT
Ralf POSNER
Silvia Schmidt
Fetiye Gueler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Henkel AG and Co KGaA
Original Assignee
Henkel AG and Co KGaA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Henkel AG and Co KGaA filed Critical Henkel AG and Co KGaA
Publication of WO2025195866A1 publication Critical patent/WO2025195866A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
    • C23G1/19—Iron or steel
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
    • C23C22/62—Treatment of iron or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/68—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous solutions with pH between 6 and 8
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/78—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides

Definitions

  • the present invention relates to a method for cleaning and degreasing a plurality of components comprising surfaces of zinc-magnesium hot-dip coated steel, in which the components are brought into contact with an alkaline, aqueous cleaner having a pH of at least 9.50, which contains a minimum amount of oxoanions of the elements B, C, N, P, S and Cl in their respective highest oxidation state, a minimum amount of bivalent metal cations of the elements Zn, Mg and/or Ca, and an organic complexing agent having at least one phosphonate group.
  • the invention further relates to a method for cleaning and corrosion-protecting surface treatment using the method for cleaning and degreasing and to an alkaline, aqueous composition suitable for the method for cleaning and degreasing.
  • a zinc and magnesium coating can provide significantly increased corrosion protection and, particularly after coating with organic topcoats and dip coatings, outstanding resistance to corrosive delamination. This improved property profile allows coatings to be provided in thinner layers that still meet the high requirements for repaintability and corrosion protection.
  • Magnesium-alloyed zinc coatings on steel are commonly used in automotive manufacturing as flat strip products and so-called hot-dip galvanized (ZM) steel strip.
  • ZM hot-dip galvanized
  • Such zinc-magnesium hot-dip coated steel contains approximately 1.5 to 8 wt.% of the metals aluminum and magnesium in the metallic coating, with the magnesium content being at least 0.2 wt.%.
  • the basic suitability of these coatings to be formed, pretreated, and coated using conventional and state-of-the-art processes is generally recognized and proven (Characteristic Properties 095 E, "Continuously Hot-Dip Coated Steel Strip and Sheet," Chapters 8 and 10, 2017 edition, German Steel Association).
  • WO 2023/036889 A1 therefore proposes conditioning the hot-dip galvanized (ZM) surfaces after degreasing but before a corrosion-protective pretreatment, which can be a conversion coating based on the elements Zr and/or Ti, in order to counteract the aging of conventional cleaning and degreasing baths associated with high component throughput and the resulting deterioration in the wettability of the hot-dip galvanized (ZM) surfaces.
  • Materials with zinc-magnesium coatings therefore require sophisticated process control to be successfully and, above all, reliably pretreated for corrosion protection, especially when a large number of components need to be coated with high-quality, automated coatings in a paint line. Further approaches are needed here that support simpler process control for corrosion protection pretreatment, encompassing the stages of degreasing, conversion layer formation, and painting, and that contribute to achieving satisfactory results in the series treatment of a large number of components, largely independent of bath aging, thus exploiting the full potential of zinc-magnesium hot-dip coated materials in corrosion protection.
  • the state-of-the-art approaches of intensive bath maintenance to keep the cleaning and degreasing baths as free from contamination as possible and to replace them with fresh bath solutions as early as possible are economically disadvantageous and problematic with regard to the desirable resource-saving use of process chemicals.
  • ZM hot-dip galvanized
  • the present invention therefore aims to establish a process for the serial treatment of a large number of components that is suitable for reliably cleaning and pretreating zinc-magnesium hot-dip coated steel with a conventional process sequence, thus without additional wet-chemical treatment steps.
  • the cleaning of components exposed to forming and corrosion protection oils must be carried out largely independently of the oil load absorbed by the cleaner of the degreasing bath. Reliability is usually guaranteed when the zinc-magnesium hot-dip coated steel surfaces are completely wettable with water after cleaning. Only then can a satisfactory result be achieved in the subsequent corrosion protection conversion treatment based on aqueous compositions without a deterioration in performance during (quasi-)continuous operation of a pretreatment line.
  • the cleaning and, if necessary, degreasing process must be suitable for components with different metal surfaces, in particular surfaces made of steel, zinc, aluminum and magnesium, and must also be usable in conventional zinc phosphating systems as well as in conversion coatings based on the elements Zr and/or Ti.
  • the present invention relates to a method for cleaning and degreasing a plurality of components in series, in which the components of the series at least partially have surfaces of zinc-magnesium hot-dip galvanized steel, and in which at least the zinc-magnesium hot-dip galvanized steel surfaces of the components of the series are each cleaned with an alkaline, aqueous cleaner with a pH value of at least 9.50 containing
  • Cleaning and degreasing within the meaning of the present invention serves to free the surfaces of components, in particular metal surfaces, from organic contaminants, in particular technical oils such as corrosion inhibitors and forming oils, in order to provide metal surfaces that are as completely water-wettable as possible, in particular completely water-wettable zinc-magnesium hot-dip coated steel surfaces.
  • the components are brought into contact with the previously defined alkaline-aqueous cleaner in the process according to the invention, which is usually provided for application in one or more so-called system tanks, i.e., stored there for contacting and kept ready for application, e.g., by immersing the components in a cleaning bath, which then forms the system tank.
  • the part of a pretreatment line that serves for cleaning and degreasing and that includes the system tanks that store the cleaner for application is referred to as the cleaning and degreasing stage.
  • This stage is usually followed, and this is also the subject of the present invention, by further wet-chemical treatment steps and process steps for applying a corrosion-protective coating to the metal surfaces, in particular at least the zinc-magnesium hot-dip coated steel surfaces of the components in the series.
  • Cleaning and degreasing of components in series occurs when, for a large number of components, at least the zinc-magnesium hot-dip coated steel surfaces are brought into contact with the alkaline, aqueous cleaner.
  • This contacting preferably takes place in one or more system tanks that provide the alkaline, aqueous cleaner for contacting, with the individual components being brought into contact sequentially and thus separated in time.
  • the system tank is the container in which the alkaline, aqueous cleaner is located for the purpose of cleaning and degreasing.
  • a steady-state amount of organic contaminants absorbed by the alkaline, aqueous cleaner is built up, which depends on the degree of contamination of the components and the inflow and outflow rates of cleaner and cleaner components.
  • the present method according to the invention is characterized in that, largely independent of the proportion of organic Contamination in the alkaline, aqueous cleaner can reliably achieve high water wettability on the zinc-magnesium hot-dip coated steel surfaces.
  • the components comprise steel material provided with a metallic zinc-magnesium coating, the coating being applied from a melt of the alloy components.
  • Such hot-dip galvanizing processes are known in the art collectively as hot-dip galvanized (ZM) steel and represent metallic coatings containing 1.5 to 8 wt.% of the metals aluminum and magnesium, with the proportion of magnesium in the metallic coating preferably being at least 0.2 wt.%.
  • ZM hot-dip galvanized
  • the material can be a uniform material or a coating.
  • galvanized steel grades consist of both steel and zinc, whereby at the cut edges and grinding points of, for example, an automobile body made of galvanized steel, steel surfaces can be exposed, and according to the invention, the steel material is then cleaned and degreased. Therefore, if the focus within the scope of the present invention is on the cleaning and degreasing of a component composed of a specific metallic material, this includes all materials and coatings that contain more than 50 at.% of the respective element of the named material. A component with a galvanized coating therefore contains more than 50 at.% zinc in the metallic coating.
  • the process according to the invention is not limited to hot-dip galvanized (ZM) steel, so that the common substrates provided by the steel industry, such as steel, in particular cold-rolled steel (CRS), as well as electrolytically galvanized (ZE) or hot-dip galvanized (Z), alloy galvanized, in particular (ZF), (ZA), or aluminum-coated (AZ), (AS) steel, can also be considered as additional components of the components.
  • Light metals such as aluminum and magnesium, as well as their alloys, can also be treated in the process according to the invention together with the hot-dip galvanized (ZM) steel of the component, and can be cleaned and degreased in the process.
  • the process according to the invention is characterized by the fact that it is suitable for providing the common metallic materials composed of iron, zinc, aluminum and magnesium with a high water wettability, which is the prerequisite for a successful corrosion-protective pretreatment, e.g. a zinc phosphating or amorphous conversion coating based on the elements Zr and/or Ti, on these metal surfaces.
  • a successful corrosion-protective pretreatment e.g. a zinc phosphating or amorphous conversion coating based on the elements Zr and/or Ti
  • Particularly preferred is an embodiment in which the components of the series are composed of galvanized steel, steel and/or aluminum in addition to hot-dip galvanized (ZM) steel.
  • ZM hot-dip galvanized
  • the components of the series represent composite structures, preferably automobile bodies, that are composed of semi-finished products of hot-dip galvanized (ZM) steel and of semi-finished products of galvanized steel and aluminum, particularly preferably of semi-finished products of hot-dip galvanized (ZM) steel and of semi-finished products of galvanized steel, aluminum and steel.
  • ZM hot-dip galvanized
  • ZM hot-dip galvanized
  • the components cleaned and degreased according to the present invention can be any spatial structure of any shape and design originating from a manufacturing process, in particular semi-finished products such as strips, sheets, rods, pipes, etc., and composite structures assembled from the aforementioned semi-finished products.
  • the composite structures assembled from different materials are usually in the form of cut, formed, and joined flat products by welding, gluing, and/or flanging.
  • the components to be cleaned and degreased in series according to the present invention are preferably selected from automobile bodies or parts thereof, heat exchangers, profiles, pipes, tanks, or tubs.
  • the inventive method for cleaning and degreasing components with hot-dip galvanized (ZM) steel surfaces serves, as already mentioned, to provide a metal surface that is readily wettable by water, which is then excellently conditioned for subsequent corrosion protection treatment based on essentially inorganic conversion coatings, in particular based on crystalline phosphate layers or those based on amorphous thin layers of oxide, hydroxide compounds of the elements Zr and/or Ti.
  • the inventive method is therefore intended to be operated as a cleaning and degreasing stage, in which contaminants such as corrosion protection and forming oils are effectively removed from the surfaces of the components and completely absorbed by the alkaline-aqueous cleaner, then accumulate in the system tank of the cleaning and degreasing stage.
  • the alkaline aqueous cleaner contains a special combination of complexing agents and inorganic additives dissolved in water, consisting of phosphates and bivalent metal cations of the elements Zn, Mg and/or Ca, which support the cleaning and, in particular, make and maintain the hot-dip galvanized (ZM) surfaces easily wettable with water.
  • phosphate ions as oxoanions of the element P in its highest oxidation state dissolved in water are the oxoanions of orthophosphoric acid (H3PO4).
  • a quantity of further oxoanions of the elements B, C, N, S and CI in their respective highest oxidation state in addition to the quantities of phosphate ions required or preferred according to the invention can also contribute to water wettability and thus help to keep the phosphate content in the cleaner moderate.
  • Carbonate, nitrate and sulfate ions, especially carbonate and nitrate ions, are particularly effective for this purpose.
  • the alkaline, aqueous cleaner therefore contains at least 10.0 mmol/kg of phosphate ions dissolved in the aqueous phase and additionally at least one oxoanion dissolved in the aqueous phase selected from borate, carbonate, nitrate, sulfate and/or chlorate ions, preferably selected from carbonate, nitrate and/or sulfate ions, particularly preferably from carbonate and/or nitrate ions, in an amount such that the proportion of oxoanions of the elements B, C, N, P, S and CI dissolved in the aqueous phase in their respective highest oxidation state is at least 30.0 mmol/kg in total, preferably the proportion
  • aqueous cleaner is at least 6.0 mmol/kg, preferably at least 8.0 mmol/kg, and particularly preferably at least 10.0 mmol/kg.
  • the total proportion of divalent cations of the elements Zn, Mg, and/or Ca should not exceed 100 mmol/kg, particularly preferably not exceeding 50 mmol/kg, as this entails the requirement for a higher proportion of complexing agent.
  • the presence of the complexing agent containing phosphonate groups serves to complex the bivalent metal cations contained in the cleaner and also the Complexation of the metal ions absorbed into the cleaner from the components during pickling processes, particularly zinc ions from the component surfaces formed by hot-dip galvanized (ZM) steel.
  • the complexing agent therefore serves to stabilize the cleaner and prevent the precipitation of the inorganic additives dissolved in water.
  • the alkaline aqueous cleaner therefore contains an amount of complexing agents with at least one phosphonate group such that the molar ratio of these complexing agents to the total amount of divalent cations of the elements Zn, Mg, and/or Ca is above 0.60.
  • the molar ratio of organic complexing agents which have at least one phosphonate group to the amount of zinc ions dissolved in the aqueous phase must be below the value 2.1, preferably below the value 2.0, particularly preferably below the value 1.9, very particularly preferably below the value 1.8 and especially preferably below the value 1.7, and in turn preferably the molar ratio of organic complexing agents which have at least one phosphonate group to the total amount of divalent cations of the elements Zn, Mg and/or Ca is below the value 2.1, preferably below the value 2.0, particularly preferably below the value 1.9, very particularly preferably below the value 1.8 and particularly preferably below the value 1.7.
  • All water-soluble complexing agents are suitable as organic complexing agents containing at least one phosphonate group.
  • the complexing agent is preferably selected from di- and/or triphosphonic acids, particularly preferably from etidronic acid and/or aminotrimethylenephosphonic acid, and especially preferably from etidronic acid.
  • the proportion of organic complexing agents containing at least one phosphonate group in the alkaline-aqueous cleaner is at least 2.0 mmol/kg.
  • the concentration of an active component or compound is specified as a molar amount per kilogram, this is the molar amount based on the weight of the respective total composition.
  • the pickling rate of the alkaline aqueous cleaner is low and during the contacting of at least the hot-dip coated (ZM) steel surfaces of the components with the cleaner in the inventive cleaning and degreasing process, not more than 0.2 g/ m2 of zinc, based on the hot-dip coated (ZM) surfaces, preferably based on all galvanized surfaces of the components, is pickled off, i.e. passes from the metallic coating into the aqueous phase of the cleaner.
  • the pickling rate can be increased by increasing the proportions of the bivalent cations selected from Zn, Ca and/or Mg, in particular the proportion of zinc ions, or by reducing the proportion of Complexing agents, in particular the proportion of organic complexing agents that contain at least one phosphonate group, can be reduced.
  • the addition of complexing agents that do not contain a phosphonate group can be useful for the formulation of non-pickling or only slightly pickling cleaners.
  • ⁇ -Hydroxycarboxylic acids such as gluconic acid are particularly well suited for this purpose.
  • aqueous cleaner in which no more than 0.2 g/ m2 of zinc is pickled off, based on the hot-dip coated (ZM) surfaces, preferably based on all galvanized surfaces of the components, the alkaline, aqueous cleaner therefore additionally contains at least one organic complexing agent that does not contain a phosphonate group and is preferably selected from ⁇ -hydroxycarboxylic acids.
  • the pickling rate can be determined after non-pickling degreasing of a component or component section by bringing the component or component section into contact with the respectively selected alkaline aqueous cleaner under the respectively selected and intended process conditions, in particular duration, temperature, type of application, components or component sections, and determining the weight loss, which is then equated with the amount of zinc removed, by differential gravimetry.
  • the alkaline, aqueous cleaner contains at least one surface-active organic compound, preferably selected from surfactants, for effective degreasing, i.e., removal of organic soils and industrial oils.
  • surfactants within the meaning of the present invention are considered to be surface-active organic compounds that, for their surface activity, are composed of a hydrophilic and at least one lipophilic molecular component or of a lipophilic and at least one hydrophilic molecular component, wherein the molecular weight of the surface-active organic compound does not exceed 2000 g/mol.
  • the surfactants used in the alkaline aqueous cleaner can be selected from anionic surfactants, cationic surfactants, zwitterionic surfactants, and nonionic surfactants, with the use of nonionic surfactants generally being preferred.
  • Particularly suitable nonionic surfactants as components of the alkaline aqueous cleaner for degreasing components comprising hot-dip galvanized (ZM) surfaces are those whose HLB value (hydrophilic-lipophilic balance) is at least 8, more preferably at least 10, especially preferably at least 12, but particularly preferably not more than 18, especially preferably not more than 16.
  • the HLB value serves as a quantitative reference value for classifying nonionic surfactants with regard to their miscibility with water or their ability to form O/W emulsions.
  • the nonionic surfactant is broken down into a lipophilic and a hydrophilic group.
  • the HLB value is then calculated as follows and can take values from zero to 20 on the arbitrary scale:
  • HLB 20 (1 -ML/M) with ML: Molar mass of the lypophilic group of the non-ionic surfactant M: Molar mass of the non-ionic surfactant
  • preferred nonionic surfactants in the alkaline aqueous cleaner of the process according to the invention are those selected from alkoxylated alkyl alcohols, alkoxylated fatty amines, and/or alkyl polyglycosides, particularly preferably from alkoxylated alkyl alcohols and/or alkoxylated fatty amines, especially preferably from alkoxylated alkyl alcohols.
  • the alkoxylated alkyl alcohols and/or alkoxylated fatty amines are preferably end-capped for a defoaming effect, particularly preferably with an alkyl group, which in turn preferably has no more than 8 carbon atoms, particularly preferably no more than 4 carbon atoms.
  • those alkoxylated alkyl alcohols and/or alkoxylated fatty amines which are present in ethoxylated and/or propoxylated form are used as nonionic surfactants in the alkaline aqueous cleaner, wherein the number of alkylene oxide units is preferably not greater than 16 in total, particularly preferably not greater than 12, especially preferably not greater than 10, but particularly preferably greater than 4, especially preferably greater than 6.
  • those alkoxylated alkyl alcohols and/or alkoxylated fatty amines are preferred as nonionic surfactants in the alkaline aqueous cleaner of the process according to the invention whose alkyl group is saturated and preferably unbranched, wherein the number of carbon atoms in the alkyl group is preferably greater than 6, particularly preferably at least 10, especially preferably at least 12, but preferably not greater than 20, particularly preferably not greater than 18, especially preferably not greater than 16.
  • alkoxylated alkyl alcohols and/or alkoxylated fatty amines are preferred as the surfactant component of the alkaline aqueous cleaner, whose lipophilic alkyl group comprises at least 10 carbon atoms, particularly preferably at least 12 carbon atoms, wherein the longest carbon chain in the alkyl group consists of at least 8 carbon atoms and an HLB value in the range from 12 to 16 is realized.
  • Preferred representatives of the alkoxylated alkyl alcohols are, for example, selected from four to eight times ethoxylated or propoxylated C6-C12 fatty alcohols, eight to twelve times ethoxylated C12-C18 fatty alcohols, six to fourteen times propoxylated C12-C18 fatty alcohols, six to ten times ethoxylated and propoxylated C12-C14 fatty alcohols, which in turn can be end-capped with methyl, butyl or benzyl groups.
  • nonionic surfactant to be used in the alkaline aqueous cleaner which is selected from alkoxylated alkyl alcohols, alkoxylated fatty amines and/or alkyl polyglycosides, is the cloud point determined according to DIN 53 917 (1981), which is preferably above 20°C, but particularly preferably below the application temperature of the cleaner in the cleaning and degreasing stage, particularly preferably more than 5°C, but not more than 10°C below the respectively selected application temperature.
  • the alkaline aqueous cleaner can contain further complexing agents which are not organic complexing agents having at least one phosphonate group and are preferably selected from a-hydroxycarboxylic acids and/or from organic compounds having at least three carboxyl groups and at least one secondary and/or tertiary amino group in order to improve the stability of the cleaner and to avoid precipitation of poorly soluble salts, in particular when low pickling rates based on the element zinc are to be achieved in the process according to the invention.
  • further complexing agents which are not organic complexing agents having at least one phosphonate group and are preferably selected from a-hydroxycarboxylic acids and/or from organic compounds having at least three carboxyl groups and at least one secondary and/or tertiary amino group in order to improve the stability of the cleaner and to avoid precipitation of poorly soluble salts, in particular when low pickling rates based on the element zinc are to be achieved in the process according to the invention.
  • the proportion of complexing agents that are not organic complexing agents with at least one phosphonate group in the alkaline, aqueous cleaner for supporting complexation of the bivalent cations contained in the cleaner or the metal ion load absorbed by the cleaner and originating from the metallic materials of the component is preferably at least 2.0 mmol/kg, particularly preferably at least 4.0 mmol/kg, very particularly preferably at least 5.0 mmol/kg, but for reasons of economic efficiency preferably does not exceed 20.0 mmol/kg, particularly preferably not 10.0 mmol/kg.
  • Suitable and therefore preferred representatives of the organic complexing agents with at least three carboxyl groups and at least one secondary and/or tertiary amino group are ß-alaninediacetic acid, N-(1-carboxyethyl)iminodiacetic acid, iminodisuccinic acid, Diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, particularly preferably iminodisuccinic acid.
  • the pH of the alkaline, aqueous cleaner is at least 9.50, and preferably at least 10.00, for good degreasing performance.
  • the pH of the alkaline, aqueous cleaner is preferably less than 12.50, more preferably less than 12.00, and most preferably less than 11.50.
  • the alkaline aqueous cleaner is preferably provided with a specific buffer capacity so that in the process according to the invention it has a total alkalinity in points of at least 3.0, more preferably at least 6.0, most preferably at least 8.0, but preferably a total alkalinity of 30.0, more preferably 20.0 and especially preferably not exceeded 15.0.
  • the total alkalinity corresponds to the consumption of 0.1 N hydrochloric acid in milliliters after titration of a sample volume of 2 ml of the alkaline, aqueous cleaner diluted with 50 ml of deionized water (K ⁇ 1 pScrrr 1 ) in the presence of the indicator bromocresol green (change point: pH 3.6) at a temperature of 20 °C.
  • any builder known in the art that represents alkaline-reacting compounds or a mixture of such compounds can be used.
  • Particularly suitable and established builders are alkaline-reacting inorganic compounds, which are preferred in the context of the present invention and are particularly preferably selected from water-soluble hydroxides, carbonates, borates, silicates and/or phosphates, wherein in turn water-soluble hydroxides, carbonates and/or phosphates are preferably present, the latter in particular, as already explained in detail, being essential as an inorganic auxiliary substance for providing readily water-wettable hot-dip galvanized (ZM) surfaces.
  • ZM hot-dip galvanized
  • orthophosphates as a builder substance for building up the alkalinity is also quite advantageous and preferred according to the invention.
  • other suitable alkaline phosphate-based builders are pyrophosphates and/or tripolyphosphates.
  • Suitable carbonate-based builders are alkali metal carbonates, preferably potassium carbonate, and among the hydroxides, mixtures of alkali metal hydroxides, preferably selected from potassium hydroxide, with phosphoric acid are preferred alkaline builders/builder systems.
  • the alkaline aqueous cleaner is formulated without the use of silicates or borates, so that the cleaner preferably contains less than 100 mg/kg, particularly preferably less than 20 mg/kg, very particularly preferably less than 5 mg/kg of silicates and/or borates, calculated as SiO4 or BO3 and based on the cleaner.
  • free alkalinities above 1.0 and below 10.0 are usually set, which in turn are preferred.
  • the free alkalinity is particularly preferably at least 2.0, particularly preferably does not exceed 7.0, and especially preferably does not exceed 5.0.
  • the free alkalinity corresponds to the consumption of 0.1 N hydrochloric acid in milliliters when a sample volume of 2 ml of the alkaline, aqueous cleaner diluted with 50 ml of deionized water (K ⁇ 1 pScrrr 1 ) is titrated at a temperature of 20 °C to a pH of 8.5.
  • the cleaning and degreasing process primarily serves to remove soiling, in particular industrial oils, and to provide water-wettable hot-dip galvanized (ZM) surfaces.
  • ZM hot-dip galvanized
  • the respective proportion of water-soluble compounds of an element selected from compounds of the elements Bi, Ni, Co or Cu, preferably selected from compounds of metal elements which have a more positive standard reduction potential than iron is in each case less than 20 mg/kg, preferably less than 10 mg/kg, particularly preferably less than 5.0 mg/kg and especially preferably less than 1.0 mg/kg, in each case calculated as the proportion of the respective element and based on the cleaner.
  • aqueous cleaner is less than 50 mg/kg, preferably less than 20 mg/kg and particularly preferably less than 10 mg/kg based on the cleaner.
  • the intervals for bath maintenance or reprocessing of the cleaner stored in the system tank can be spaced at greater intervals and/or the addition of freshly prepared cleaner and/or cleaner components can be reduced without any loss of performance.
  • the proportion of non-polar hydrocarbons, which is fed from forming and corrosion protection oils cleaned from the component surfaces, in the alkaline aqueous cleaner due to the series treatment of a large number of components is already at least 0.2 kg/m 3 , particularly preferably at least 0.5 kg/m 3 , especially preferably at least 1.0 kg/m 3 .
  • the proportion of non-polar hydrocarbons in the alkaline aqueous cleaner can be determined in a hydrochloric acid (turnover point methyl orange) sample of the degreasing bath to which an aliquot part (1/10) of sodium chloride and an aliquot part (1/4) of ethanol have been added.
  • the proportion of hydrocarbons is extracted from this prepared sample of the degreasing bath by shaking with an aliquot part (1/1) of petroleum ether.
  • phase separation which can be achieved by successive addition of ethanol, the petroleum ether phase is used to separate polar organic components such as fatty acids, acid esters, and nonionic surfactants, are mixed with silica gel.
  • the proportion of nonpolar hydrocarbons can be determined gravimetrically after the petroleum ether has been distilled off.
  • the series of components includes at least a number of components whose total surface area formed by the metallic materials of the components is greater than the following term:
  • KWcrit typically critical amount or preferred minimum amount of non-polar hydrocarbons in the alkaline aqueous cleaner in kg/m 3 , amounting to 0.2 kg/m 3 , particularly preferably 0.5 kg/m 3 , very particularly preferably 1.0 kg/m 3
  • Amroc Change in the area-related carbon content on the surfaces of the components formed by the metallic materials after contact with the alkaline aqueous cleaner in kg/m 2
  • the carbon layer remaining on the surface of the component formed by the metallic materials can be determined by pyrolytic decomposition.
  • a representative component section of a defined area of each metallic material is heated to a substrate temperature (PMT) of 550°C in an oxygen atmosphere, and the amount of carbon dioxide released is quantitatively recorded as the amount of carbon using an infrared sensor, for example, using the LECO® RC-412 Multiphase Carbon Determinator (Leco Corp.).
  • the change in the area-related carbon content for each metallic material can then be determined immediately before cleaning and degreasing and immediately after the first rinse with deionized water (K ⁇ I pScrrr 1 ) after cleaning and degreasing, and calculated for the entire component according to the specific area proportion of the respective materials.
  • a carbon coating of less than 0.20 g/m 2 remains on the surface of the components of the series formed by the metallic materials, whereas the surface of the components of the series formed by the metallic materials previously, i.e. before passing through the inventive Process, i.e. immediately before the first contact with the alkaline aqueous cleaner, preferably has a carbon coating of at least 0.50 g/m 2 , which originates from the organic soiling already mentioned, in particular forming and corrosion protection oils.
  • the alkaline, aqueous cleaner is applied and thus brought into contact with the components of the series preferably at a temperature of at least 30°C, particularly preferably at a temperature of at least 40°C, but preferably below 60°C.
  • the alkaline, aqueous cleaner can be brought into contact with the components of the series using application methods established in the prior art. These include, in particular, immersion, rinsing, spraying, and/or atomization. The immersion of the components of the series into a system tank of the cleaning and degreasing stage containing the corresponding alkaline, aqueous cleaner and/or by spraying the cleaner stored in a system tank.
  • the present invention relates to an alkaline, aqueous composition particularly suitable for the cleaning process according to the invention, having a pH in the range from 9.50 to 12.50, containing
  • a total of at least 30.0 mmol/kg preferably a total of at least 50.0 mmol/kg, particularly preferably a total of at least 60.0 mmol/kg of carbonate ions, nitrate ions and/or phosphate ions dissolved in the aqueous phase, wherein at least 10.0 mmol/kg, preferably at least 20.0 mmol/kg but less than 100.0 mmol/kg, preferably less than 80.0 mmol/kg of phosphate ions are contained,
  • aqueous composition according to the invention With regard to the alkaline, aqueous composition according to the invention, the same preferred embodiments apply with regard to individual components, insofar as they are compatible with the embodiments of the alkaline, aqueous composition according to the invention already listed here, as well as with regard to other physico-chemical properties, which also apply to the alkaline, aqueous cleaner in the cleaning and degreasing process according to the invention.
  • suitable and preferred surface-active organic compounds the pH value, the alkalinity, the alkaline builders used and the upper limits for interfering metal ions, which have a more positive standard reduction potential than iron, for iron(III) ions or the upper limits for undesirable alkaline builders such as borates and silicates.
  • the cleaning and degreasing process according to the invention serves to reliably remove soiling from components in series production and, in doing so, to provide metal surfaces, in particular hot-dip galvanized (ZM) steel surfaces, which in turn are excellently suited for corrosion-protective pretreatment.
  • ZM hot-dip galvanized
  • Such corrosion-protective pretreatment of metal surfaces, at least the surfaces of hot-dip galvanized (ZM) steel can be conventional zinc phosphating or a conversion treatment based on the elements Zr and/or Ti, during which thin, amorphous, oxidic/hydroxidic layers are formed.
  • the process according to the invention offers the advantage that, due to the good water wettability, extremely homogeneous, defect-free conversion coatings are accessible, which are a prerequisite for both good corrosion protection and an optically homogeneous paint layer structure.
  • the present invention therefore relates to a process in which contacting with the alkaline, aqueous cleaner is immediately followed, but with an intermediate rinsing step, by a conversion treatment by contacting with an acidic, aqueous composition either for zinc phosphating or for conversion treatment based on the elements Zr and/or Ti.
  • a rinsing step serves primarily, preferably exclusively, to remove the wet film adhering to the components from the cleaning and degreasing step and thus to completely or partially remove soluble residues, particles, and active components of the alkaline, aqueous cleaner that would otherwise be carried over into the conversion treatment step while adhering to the component.
  • the components which have at least partially hot-dip galvanized (ZM) steel surfaces each undergo the successive process steps i)-iii): i) cleaning and optionally degreasing according to the previously described method according to the invention for cleaning and degreasing; iii) conversion treatment by bringing into contact with an acidic, aqueous composition having a pH in the range of 2.5 to 4.0 containing
  • a lacquer system preferably by contacting with an aqueous dispersion of an organic binder, wherein the lacquer system preferably a dip coating, particularly preferably an electrocoating coating (“coating stage”).
  • the components which have at least partially hot-dip galvanized (ZM) steel surfaces each undergo the successive method steps i)-iii): i) cleaning and optionally degreasing according to the previously described method according to the invention for cleaning and degreasing ("cleaning and degreasing stage"); ii) conversion treatment by bringing into contact with an acidic, aqueous composition having a pH in the range from 2.50 to 5.20 containing at least 0.05 mmol/kg of compounds of the elements Zr and/or Ti dissolved in water and preferably an amount of free fluoride ("conversion stage”); and iv) deposition of a coating system, preferably by bringing into contact with an aqueous dispersion of an organic binder, wherein the coating system is preferably a dip coating, particularly
  • a Zr/Ti conversion treatment according to the invention should preferably be carried out in process step ii) with acidic aqueous compositions which contain at least 1.00 mmol/kg of free fluoride in order to further improve paint adhesion to the hot-dip galvanized (ZM) surfaces.
  • the proportion of free fluoride in the acidic, aqueous composition in process step ii) is less than 7.50 mmol/kg, more preferably less than 6.00 mmol/kg, most preferably less than 5.00 mmol/kg and especially preferably less than 4.00 mmol/kg.
  • the amount of free fluoride in the respective stages of the pretreatment according to the invention is to be determined potentiometrically at 20°C in the respective provided solution after calibration with fluoride-containing buffer solutions without pH buffering using a fluoride-sensitive measuring electrode.
  • Suitable sources of free fluoride for the acidic, aqueous composition are water-soluble complex fluorides of the elements Zr, Ti and/or Si, preferably of the elements Zr and/or Ti, particularly preferably of the element Zr, and/or hydrofluoric acid, ammonium bifluoride and/or water-soluble alkali metal fluorides.
  • the acidic, aqueous composition in process step ii) of the Zr/Ti conversion treatment it is first necessary to ensure that the compounds of the elements Zr and/or Ti dissolved in water do not form brines due to hydrolysis, which are no longer available for the conversion layer formation.
  • the pickling rate for common metallic materials should be sufficiently high to ensure homogeneous to form closed conversion layers, this applies in particular to the substrate hot-dip galvanized (ZM) steel.
  • the acidic, aqueous compositions do not have a pH above 5.20 and the pH is preferably less than 5.10, more preferably less than 5.00, most preferably less than 4.90, and especially preferably below 4.80.
  • the pH of the acidic aqueous composition is greater than 3.00, particularly preferably greater than 3.50, and most preferably greater than 4.00.
  • the aim is to build up a conversion coating based on oxidic/hydroxidic compounds of the elements Zr and/or Ti, preferably the element Zr, that is as homogeneous and compact as possible.
  • the contacting is therefore carried out for at least a duration for which a layer thickness of at least 20 mg/m 2 , particularly preferably of at least 40 mg/m 2 is brought about on the surfaces of the hot-dip galvanized (ZM) steel, but the contacting preferably does not last so long that a layer thickness of more than 300 mg/m 2 , particularly preferably of more than 200 mg/m 2 , very particularly preferably of more than 120 mg/m 2 , especially preferably more than 80 mg/m 2 , in each case based on the elements Zr and/or Ti, results on the hot-dip galvanized (ZM) surfaces.
  • the coating thicknesses can be determined by X-ray fluorescence analysis (XRF).
  • the treatment time required for the preferred coating thicknesses i.e., the duration of contact with the acidic, aqueous composition at a preferred temperature in the range of 10-60 °C, should be in the range of 10 seconds to 300 seconds.
  • a Zr/Ti conversion treatment according to the invention is preferred, in which the proportion of compounds of the elements Zr and/or Ti dissolved in water in the acidic, aqueous composition in process step ii) is preferably at least 0.10 mmol/kg, more preferably at least 0.30 mmol/kg, and most preferably at least 0.40 mmol/kg.
  • the contents of compounds of the elements Zr and/or Ti dissolved in water should preferably be below 5.0 mmol/kg, particularly preferably below 3.0 mmol/kg and most preferably below 2.0 mmol/kg based on the elements Zr and/or Ti.
  • an amorphous oxide/hydroxide coating based on the elements Zr and/or Ti, preferably the element Zr is to be created, and accordingly, the compounds of the elements Zr and/or Ti dissolved in water are included.
  • the term "dissolved in water” encompasses molecularly dissolved species and compounds that dissociate in aqueous solution and form hydrated ions.
  • Typical representatives of these compounds are titanyl sulfate (TiO(SO4)), titanyl nitrate (TiO(NO5)2) and/or hexafluorotitanic acid (H2TiFe) and their salts, or ammonium zirconium carbonate ((NH4)2ZrO(CO3)2) and/or hexafluorozirconic acid (H2ZrFe) and their salts.
  • the compounds dissolved in water in the conversion stage are preferably selected from fluoro acids and/or fluoro complexes of the elements Zr and/or Ti, as well as their water-soluble salts. Conversion layer formation based on fluoro acids and/or fluoro complexes of the element Zr is particularly preferred, since such conversion layers provide improved paint adhesion.
  • the acidic, aqueous composition of the conversion stage additionally contains copper ions dissolved in water, preferably at least 0.05 mmol/kg, but again preferably less than 4.0 mmol/kg, particularly preferably less than 2.0 mmol/kg of copper ions dissolved in water.
  • Suitable sources of copper ions dissolved in water are water-soluble salts such as copper nitrate (CU(NO3)2), copper sulfate (CuSO4), and copper acetate (Cu(CH3COO)2).
  • additives known to those skilled in the art of surface treatment such as accelerators such as nitrate ions, nitrite ions, nitroguanidine, N-methylmorpholine N-oxide, hydrogen peroxide in free or bound form, hydroxylamine in free or bound form, reducing sugars, and/or wetting agents such as nonionic surfactants, and/or polymers such as polyamidoamines, and/or cations/compounds of the elements Mg, Ca, Al, Si, Sn, Bi and/or Mo may be included to improve the layer formation kinetics, wettability and corrosion-protective properties in the context of the Zr/Ti conversion treatment according to the invention.
  • accelerators such as nitrate ions, nitrite ions, nitroguanidine, N-methylmorpholine N-oxide, hydrogen peroxide in free or bound form, hydroxylamine in free or bound form, reducing sugars, and/or wetting agents such as nonionic surfactants, and/or polymers such
  • the acidic, aqueous composition in the conversion stage is therefore substantially free of hydrolyzable organic silanes/siloxanes and preferably contains less than 10 mg/kg of hydrolyzable organic silanes/siloxanes calculated as Si(OCH2CH3)4.
  • the application and thus the contacting of the acidic, aqueous composition in the conversion stage of both the conversion treatment according to the invention and the zinc phosphating according to the invention preferably takes place at at least 30°C, particularly preferably at at least 40°C, but preferably below 60°C.
  • the acidic, aqueous composition of the conversion stage can be brought into contact with the components of the series using application methods established in the prior art. These include, in particular, immersion, rinsing, spraying, and/or spraying, with application by immersion and/or spraying, and in particular, immersion of the components of the series in a system tank containing the corresponding acidic, aqueous composition, being preferred.
  • At least the surfaces of the components formed by the hot-dip galvanized (ZM) steel and pretreated to provide corrosion protection in the respective process step ii), preferably all surfaces formed by metallic materials, are provided with a first coating system, preferably by contacting the component or at least said surfaces of the hot-dip galvanized (ZM) steel pretreated to provide corrosion protection with an aqueous dispersion containing an organic binder.
  • the coating system is therefore preferably deposited directly from the aqueous phase as a coating of the organic binder of the aqueous dispersion precipitated onto said surfaces of the components, which is typically subjected to a thermal post-treatment for film formation and curing.
  • the coating in the coating stage is preferably applied as a dip coating, particularly preferably as an electrocoating, again preferably as a cathodic electrocoating.
  • the organic binder of the aqueous dispersion is preferably based on amine-modified film-forming polyepoxides, which preferably additionally comprise blocked and/or unblocked organic compounds containing isocyanate groups as hardeners.
  • Inorganic pigments are also often a component of the aqueous dispersion and a preferred additive for improving corrosion protection.
  • the aqueous phase of the dispersion containing the binder also preferably contains small amounts of compounds of the elements yttrium and/or bismuth dissolved or dispersed in water, which have a positive effect on crosslinking and film formation.
  • the preferred pH of the aqueous dispersion in the coating stage is in the range from 5.0 to 6.0, particularly preferably in the range from 5.4 to 5.8.
  • the aqueous dispersion is preferably applied at a temperature of at least 30°C, particularly preferably at a temperature of at least 40°C, but preferably below 60°C.
  • the aqueous dispersion from the coating stage can be brought into contact with the series components using application methods established in the prior art. These include, in particular, dipping, spraying, and roller application. Application by dipping, and in particular, immersing the series components in a system tank containing the corresponding aqueous dispersion of the organic binder, is preferred and, in the case of dipping coatings, is already predetermined by the type of coating system.
  • ZM zinc-magnesium hot-dip coated steel
  • the degreasing baths (A) and (B) were mixed with 3 grams of the corrosion protection oil Anticorit® RP 4107 LV from Fuchs Europe Schmierstoffe GmbH per kilogram of bath solution.
  • Table 1 shows that the presence of zinc (V3 and V7 vs. E1) and phosphate ions (V4-V6 vs. E1) is a prerequisite for a satisfactory result in the water break test, and even increasing proportions of the oxoanions of carbonate and nitrate (V4 to V6) in the presence of zinc ions alone are not sufficient to achieve the desired water wettability of the (ZM) substrates in an oil-contaminated and thus practical cleaning bath. In the absence of zinc ions, water wettability can be increased to a certain extent by adding the phosphonate-group-containing complexing agent HEDP (cf. VIVO), but only with longer spray degreasing (V3) and at the expense of increased pickling removal.
  • HEDP phosphonate-group-containing complexing agent

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Abstract

La présente invention concerne un procédé de nettoyage et de dégraissage d'une pluralité de composants comprenant des surfaces d'acier galvanisées à chaud par immersion dans du zinc-magnésium, dans lequel les composants sont mis en contact avec un nettoyant aqueux alcalin ayant une valeur de pH d'au moins 9,50, qui a une quantité minimale d'oxyanions des éléments B, C, N, P, S et Cl dans leur état d'oxydation respectivement maximal, une quantité minimale de cations métalliques bivalents des éléments Zn, Mg et/ou Ca, une quantité minimale d'ions zinc étant requise, ainsi qu'un agent complexant organique qui contient au moins un groupe phosphonate. L'invention concerne en outre un procédé de nettoyage et de traitement anti-corrosion de surface utilisant le procédé de nettoyage et de dégraissage, ainsi qu'une composition aqueuse alcaline appropriée pour le procédé de nettoyage et de dégraissage.
PCT/EP2025/056722 2024-03-18 2025-03-12 Procédé de nettoyage et de dégraissage de composants comprenant des surfaces d'acier galvanisées à chaud par immersion dans du zinc-magnésium Pending WO2025195866A1 (fr)

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EP24164239.6A EP4621096A1 (fr) 2024-03-18 2024-03-18 Procédé de nettoyage et de dégraissage de pièces comprenant des surfaces en acier fini par immersion à chaud au zinc-magnésium

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160010216A1 (en) 2013-02-18 2016-01-14 Arcelormittal Method for the production of metal sheet having a znmg or znalmg coating, comprising the application of a basic solution of a magnesium ion complexing agent, and resulting metal sheet.
US20170009363A1 (en) * 2015-07-10 2017-01-12 Yuken Industry Co., Ltd. Reactive-type chemical conversion treatment composition and production method of member with chemical conversion coated surface
WO2023036889A1 (fr) 2021-09-13 2023-03-16 Henkel Ag & Co. Kgaa Procédé de nettoyage et/ou de prétraitement anticorrosion d'une pluralité de composants comprenant de l'acier galvanisé (zm)
EP4283012A1 (fr) * 2022-05-25 2023-11-29 Henkel AG & Co. KGaA Procédé de nettoyage alcalin des bandes en acier allié zinc-magnésium

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160010216A1 (en) 2013-02-18 2016-01-14 Arcelormittal Method for the production of metal sheet having a znmg or znalmg coating, comprising the application of a basic solution of a magnesium ion complexing agent, and resulting metal sheet.
US20170009363A1 (en) * 2015-07-10 2017-01-12 Yuken Industry Co., Ltd. Reactive-type chemical conversion treatment composition and production method of member with chemical conversion coated surface
WO2023036889A1 (fr) 2021-09-13 2023-03-16 Henkel Ag & Co. Kgaa Procédé de nettoyage et/ou de prétraitement anticorrosion d'une pluralité de composants comprenant de l'acier galvanisé (zm)
EP4283012A1 (fr) * 2022-05-25 2023-11-29 Henkel AG & Co. KGaA Procédé de nettoyage alcalin des bandes en acier allié zinc-magnésium

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