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
  • 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
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/02—Inorganic compounds ; Elemental compounds
  • C11D3/04—Water-soluble compounds
  • C11D3/046—Salts
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/20—Organic compounds containing oxygen
  • C11D3/2075—Carboxylic acids-salts thereof
  • C11D3/2086—Hydroxy carboxylic acids-salts thereof
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/26—Organic compounds containing nitrogen
  • C11D3/33—Amino carboxylic acids
• • 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
  • C23C22/06—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
• • 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
  • C23C22/78—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
  • 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
  • C23G1/16—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions using inhibitors
  • C23G1/18—Organic inhibitors
• • 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
  • 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
  • C23G1/20—Other heavy metals
• • 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
  • C23G1/22—Light metals
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
  • C11D2111/10—Objects to be cleaned
  • C11D2111/14—Hard surfaces
  • C11D2111/16—Metals
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
  • C11D2111/10—Objects to be cleaned
  • C11D2111/14—Hard surfaces
  • C11D2111/20—Industrial or commercial equipment, e.g. reactors, tubes or engines

Definitions

• the present invention relates to a method for wet-chemical cleaning and conditioning of hot-dip galvanized (ZM) steel by bringing it into contact with an alkaline, aqueous composition containing magnesium ions dissolved in water and at least one complexing agent. Also included is a process for the corrosion-protective pretreatment of strip steel with hot-dip galvanizing (ZM) on one or both sides, in which cleaning according to the invention is followed by a wet chemical conversion coating and a paint layer build-up thereon. Furthermore, an alkaline, aqueous composition containing both magnesium ions and iron ions as well as a system of complexing agents, which is particularly suitable for cleaning and subsequent anti-corrosion surface treatment, is the subject of the present invention.
• the metallic coating produced on hot-dip galvanized (ZM) steel strip contains approximately 1.5 to 8% by weight of the metals aluminum and magnesium, with the proportion of magnesium being at least 0.2% by weight.
• the fundamental suitability of these coatings to be formed, pretreated and coated in 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, edition 2017, vealism Stahl), however, due to the special composition of the coating and the native oxide layer, there are special features that must be taken into account, especially during cleaning and pre-treatment, in order to achieve the most homogeneous and reproducible coating result possible and thus optimal corrosion protection behavior or the desired surface functionality.
• the proposed complexing agents are selected from organic acids or their salts and preferably selected from glycine and diphosphoric acid.
• a pH value in the range of 7 - 11.5, especially 9 - 10 is recommended for sufficient removal of the oxidic magnesium species from the substrate surface and thus a mildly alkaline cleaning stage.
• the present invention has the task of making the strongly alkaline cleaners established in strip pretreatment lines usable for the treatment of hot-dip galvanized (ZM) strip steel without having to accept disadvantages in terms of paint adhesion and in particular with regard to blistering .
• Strongly alkaline cleaners have the technical advantage that the degreasing and cleaning of the strip steel can be carried out in just one treatment step.
• a strong alkaline degreasing step must be carried out before the conditioning process in order to achieve the desired surface quality with good paint adhesion at the same time.
• the task profile of the present invention also includes the necessary compatibility of cleaning with amorphous inorganic conversion layers applied in the pretreatment line, which significantly increase the adhesion of primer coatings and thus also the resistance of top coats to corrosive debonding and blistering.
• the present invention therefore relates, in a first aspect, to a method for cleaning and conditioning hot-dip galvanized (ZM) steel by bringing it into contact with an alkaline, aqueous composition containing at least 1.0 mmol/kg of magnesium ions dissolved in the aqueous phase and at least one water-soluble organic complexing agent, the free alkalinity of the composition being greater than 3.0 and the pH greater than 11.5.
• ZM hot-dip galvanized
• hot-dip galvanizing represents a metallic coating on steel that contains 1.5 to 8% by weight of the metals aluminum and magnesium, the proportion of magnesium in the metallic coating being preferably at least 0.2% by weight .-% lies.
• Free alkalinity or total alkalinity is determined by titrating 2 grams of the aqueous composition diluted to 50 ml with 0.1N hydrochloric acid to a pH of 8.5 or 3.6, respectively. The consumption of acid solution in ml indicates the free alkalinity or total alkalinity score.
• the pH value is defined as the negative decadal logarithm of the hydronium ion activity and can be determined directly in a sample volume of the composition using pH-sensitive glass electrodes after calibration with standard buffer solutions.
• the total alkalinity in points is greater than 5.0, particularly preferably greater than 10.0, particularly preferably greater than 12.0.
• the free alkalinity of the composition is set in points greater than 6.0, particularly preferably greater than 8.0.
• the ratio of total alkalinity to free alkalinity in points is preferably less than 3.0, particularly preferably less than 2.5, in particular less than 2.2, in order to ensure sufficient pickling in the continuous operation of a pretreatment line and is therefore an important process control variable .
• the preferred pH value of the composition in the process according to the invention is above 12.0, preferably above 12.5, so that a surface coating based on oxides/hydroxides of magnesium is retained, while oxides/hydroxides and metallic aluminum from hot-dip galvanizing are active in solution go. In this way, an enrichment of magnesium on the hot-dip galvanized steel surface and thus improved paint adhesion after primer and top coat coating is promoted.
• the pH value of the composition is preferably adjusted so that it is less than 13.5, particularly preferably less than 13.0, in order to avoid over-pickling and the associated excessive material removal on the one hand and excessive entry of zinc ions into the pretreatment stages on the other hand to avoid.
• the presence of magnesium ions dissolved in the aqueous phase of the strongly alkaline composition of the process according to the invention is also necessary for adequate protection against blistering of organic cover layers applied to hot-dip galvanized (ZM) steel.
• ZM hot-dip galvanized
• Any water-soluble magnesium salts serve as a source for magnesium ions, but nitrates, sulfates, carbonates and/or salts of ⁇ -hydroxycarboxylic acids, for example glycolic acid, lactic acid, tartaric acid, malic acid, aldaric acids, aldonic acids and/or glucoheptonic acid, are particularly suitable and therefore preferred .
• the additional layer deposit on the hot-dip galvanized (ZM) surface in the process according to the invention in the range of a few milligrams of magnesium per square meter is supported by the presence of the complexing agent and can be additionally increased by selecting certain complexing agents, which then results in a further optimization of the adhesion of on the (ZM) substrate applied organic cover layers accompanied.
• a complexing agent in the context of the present invention is a Lewis base and organic compound with a molecular weight of not more than 500 g/mol, which comprises at least two functional groups that have heteroatoms with at least one lone pair of electrons.
• the at least two functional groups of the complexing agent contained in the alkaline, aqueous composition are selected from carboxylic acid, phosphonic acid, phosphoric acid, amino and / or hydroxyl groups with the proviso that complexing agents which are at least contain an amino or hydroxyl group, also have at least one functional group selected from a carboxylic acid, phosphonic acid or phosphoric acid group.
• the complexing agent is always an acid and, in the context of the present invention, can also be contained or added to the alkaline, aqueous composition partly or completely in the form of the corresponding salt.
• the complexing agents of the alkaline, aqueous composition are therefore selected from those with a complex formation constant pK L for magnesium below 2.0, preferably below 1.5, particularly preferably below 1.0.
• Suitable weak complexing agents with a pK L value below 2.0 are preferably ⁇ -hydroxycarboxylic acids, which in turn are preferably selected from the group consisting of glycolic acid, lactic acid, tartaric acid, malic acid, aldaric acids, aldonic acids and / or glucoheptonic acid, particularly preferably at least one Aldonic acid, in particular gluconic acid and/or glucoheptonic acid and most preferably gluconic acid is selected.
• aqueous composition in the process according to the invention If weak complexing agents are combined with stronger complexing ones in the alkaline, aqueous composition in the process according to the invention, the coating of the hot-dip galvanized steel surfaces with magnesium is surprisingly increased and the adhesion to the primer and top coat is thereby further improved.
• aqueous composition is a method according to the invention in which the proportion of complexing agents in the composition is at least 2.0 mmol/kg, particularly preferably at least 4.0 mmol/kg, particularly preferably at least 5.0 mmol/kg, but the total proportion of complexing agents is preferably not greater than 50 mmol/kg, particularly preferably not greater than 40 mmol/kg, particularly preferably not greater than 30 mmol/kg, based on the composition.
• the proportion of complexing agents with a complex formation constant pK L for magnesium below 2.0, in particular aldonic acids and/or glucoheptonic acid, based on the total proportion of complexing agent is preferably at least 60 mol%, particularly preferably at least 80 mol. -%, and particularly preferably at least one further complexing agent selected from one of the groups a) or b) mentioned in the previous paragraph is included.
• Such a preferred system of complexing agents in the alkaline, aqueous composition is particularly suitable for sufficient and homogeneous surface coating of the hot-dip galvanized steel with magnesium.
• appropriately conditioned (ZM) substrates which are pretreated to protect against corrosion and coated with a primer and top coat, show excellent adhesion after forming and no blistering occurs even after weeks of storage in condensing moisture.
• the type of contact with the alkaline, aqueous composition can be freely chosen in the process according to the invention. However, dipping and spraying methods are preferred.
• the process steps i) - iv) are consecutive, but can be interrupted by intermediate steps, which can regularly represent rinsing steps, with rinsing steps being intended to remove active components from an immediately preceding wet chemical treatment step, which adhere to the strip steel as a wet film and do not need to be dried, by means of a Remove rinsing solution from the surface of the component as much as possible.
• the conversion coating in process step iii) is carried out using acidic, aqueous compositions which produce an amorphous oxidic/hydroxide coating based on the elements Zr, Ti and/or Si and contain corresponding compounds of the elements Zr, Ti and/or Si dissolved in water.
• dissolved in water includes molecularly dissolved species and compounds that dissociate in aqueous solution to form hydrated ions.
• Typical representatives of water-soluble compounds are, in addition to hexafluorotitanic acid (H 2 TiF 6 ), hexafluorozirconic acid (H 2 ZrF 6 ) and hexafluorosilicic acid (H2SiF6) and their salts, but also titanyl sulfate (TiO(SO 4 )), titanyl nitrate (TiO(NO 3 ) 2 ) and Ammonium zirconium carbonate ((NH 4 ) 2 ZrO(CO 3 ) 2 ).
• Organosilanes are also suitable as water-soluble compounds of the element Si, but these are preferably contained in addition to one or more compounds of the elements Zr and/or Ti.
• Such organosilanes preferably have at least one hydrolyzable, aliphatic radical, which is preferably selected from alkoxy groups with preferably not more than 2 carbon atoms and particularly preferably at least one non-hydrolyzable, aliphatic radical, which is preferably selected from alkyl groups with preferably not more than 6 carbon atoms, which particularly preferably additionally have at least one primary amine, glycidyl or hydroxyl group.
• Typical representatives of these organosilanes are (3-glycidyloxypropyl)trimethoxysilane and 3-aminopropyltriethoxysilane.
• a conversion coating based on the fluoro acids of the element Ti is particularly preferred in the process according to the second aspect of the present invention, since such layers form optimally when formed by drying ("dry-inplace" process) and in the acidic, aqueous medium high compatibility for addtivation with polymeric components, as in the DE 102006039633 A1 described, and therefore provide particularly good paint adhesion, so that, depending on the requirement profile, a primer coating in step vi) can be dispensed with.
• the layer layers of Zr, Ti and/or Si, in particular of Zr and/or Ti, in processes for cleaning and anti-corrosion surface treatment of strip steel must be set within a very narrow range, otherwise either the layer is too low for an inorganic, corrosion-protective layer protective paint adhesive base, or above a tolerable threshold value there is already a significant deterioration in adhesion to the primer and top coat.
• An advantage of the method according to the invention is that a wider application window is made available for conversion coating, since the performance in terms of paint adhesion only drops significantly with layer layers above 20 mg/m 2 based on the elements Zr, Ti and/or Si.
• the contacting in process step ii) takes place for such a duration or in such an application quantity that a layer of Zr, Ti and/or is formed on the hot-dip galvanized (ZM) surfaces of the strip steel after drying step iv).
• the present invention also relates to an alkaline, aqueous composition which is particularly suitable in the context of the previously described methods according to the invention for cleaning and conditioning hot-dip galvanized (ZM) steel, which establishes a system of complexing agents optimized for the formation of a homogeneous layer of magnesium.
• ZM hot-dip galvanized
• composition according to the invention all those variants of the alkaline, aqueous composition for cleaning and conditioning mentioned in the context of the first aspect of the present invention are also preferred, insofar as they do not explicitly relate to the system of complexing agents.
• composition according to the invention can also be used for the conditioning and cleaning of all other hot-dip galvanized steel types, in particular hot-dip galvanized (Z), alloy galvanized, especially (ZF), (ZA), or aluminum-coated (AZ), (AS). Steel.
• Z hot-dip galvanized
• alloy galvanized especially (ZF), (ZA), or aluminum-coated (AZ), (AS).
• AS aluminum-coated
• Steel This opens up the possibility of operating the pretreatment stages of a coil coating system with these hot-dip galvanized steel types, without the respective stages, in particular the cleaning and degreasing stage, when changing the strip steel type, for example from (ZM) to (Z) and vice versa, using wet chemicals having to “re-equip”.
• All objects and aspects relating to the present invention be it the method for conditioning and cleaning or the method for cleaning and anti-corrosion surface treatment or the alkaline, aqueous composition for conditioning and cleaning itself, have in common that the respective alkaline, aqueous composition can be additived , but certain additives mentioned below have a negative effect on the performance of conditioning and should therefore preferably not be included or should only be contained in small amounts.
• electropositive metal ions which, when present in the alkaline environment of cleaning and conditioning, deposit in metallic form on the hot-dip galvanized steel and can thereby disrupt or even prevent the formation of a layer of magnesium required for improved paint adhesion.
• the proportion of water-soluble compounds of the elements Ni or Co preferably the proportion of water-soluble compounds of metal elements which have a more positive standard reduction potential than iron, in the composition is less than 10 mg/kg, preferably less than 5 mg/kg, particularly preferably less than 1 mg/kg, in each case as a proportion of the element and based on the composition.
• the alkaline, aqueous composition in the context of all objects of the present invention preferably additionally contains iron ions dissolved in water, preferably at least 0.4 mmol/kg, particularly preferably at least 1.0 mmol/kg, very particularly preferably at least 1.5 mmol /kg of iron ions, but preferably less than 0.040 mol/kg, very particularly preferably less than 0.010 mol/kg of iron ions, each based on the composition.
• a suitable source of iron ions dissolved in water are the nitrates, sulfates, carbonates and/or salts of ⁇ -hydroxycarboxylic acids, for example glycolic acid, lactic acid, tartaric acid, malic acid, aldaric acids, aldonic acids and/or glucoheptonic acid.
• phosphates can also have a disadvantageous effect on the performance of the conditioning, i.e. the desired surface coating with magnesium, so that their total proportion includes orthophosphate and metaphosphates such as pyrophosphate in the alkaline, aqueous composition and in the context of all objects of the present invention less than 0.100 g/kg, particularly preferably less than 0.050 g/kg, particularly preferably less than 0.010 g/kg and most preferably less than 0.005 g/kg calculated as PO 4 and based on the composition.
• orthophosphate and metaphosphates such as pyrophosphate in the alkaline, aqueous composition and in the context of all objects of the present invention less than 0.100 g/kg, particularly preferably less than 0.050 g/kg, particularly preferably less than 0.010 g/kg and most preferably less than 0.005 g/kg calculated as PO 4 and based on the composition.
• water-dispersed or water-dissolved polymeric organic compounds with a molecular weight above 500 g/mol which are not surfactants, preferably not nonionic surfactants, so that their total proportion in the alkaline, aqueous composition and in the context of all objects of the present invention preferably is less than 0.100 g/kg, particularly preferably less than 0.050 g/kg, particularly preferably less than 0.010 g/kg and most preferably less than 0.005 g/kg based on the composition.
• nonionic surfactants are preferred which are selected from alkoxylated alkyl alcohols, alkoxylated fatty amines and/or alkyl polyglycosides, particularly preferably from alkoxylated alkyl alcohols and/or alkoxylated fatty amines, particularly 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 not more than 8 carbon atoms, particularly preferably not more than 4 carbon atoms.
• alkoxylated alkyl alcohols and/or alkoxylated fatty amines as nonionic surfactants which are ethoxylated and/or propoxylated, the number of alkylene oxide units preferably not being greater than 16 in total, particularly preferably not greater than 12, particularly preferably not greater than 10 , but particularly preferably greater than 4, particularly preferably greater than 6.
• those alkoxylated alkyl alcohols and/or alkoxylated fatty amines are preferred as nonionic surfactants for the additivation, the alkyl group of which is saturated and preferably unbranched, the number of carbon atoms in the alkyl group preferably being greater than 6, especially preferably at least 10, particularly preferably at least 12, but preferably not greater than 20, particularly preferably not greater than 18, particularly preferably not greater than 16.

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Citations (3)

• 2022
  • 2022-05-25 EP EP22175373.4A patent/EP4283012A1/fr active Pending
• 2023
  • 2023-05-22 WO PCT/EP2023/063633 patent/WO2023227522A1/fr unknown

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