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
  • 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
  • C23C22/07—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 phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
  • C23C22/17—Orthophosphates containing zinc cations containing also organic 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
  • 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
  • C23C22/07—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 phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
• • 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
  • C23C22/36—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 containing also phosphates
  • C23C22/362—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 containing also phosphates containing also zinc cations
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
  • C23F11/173—Macromolecular compounds
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/18—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using inorganic inhibitors
  • C23F11/187—Mixtures of inorganic inhibitors
  • C23F11/188—Mixtures of inorganic inhibitors containing phosphates

Definitions

• the present invention relates to a method for layer-forming zinc phosphating of metallic surfaces using a colloidal, aqueous solution as the activation step, a zinc phosphate layer with a layer weight of less than 2.0 g/m 2 being deposited on the zinc surfaces in the method step following activation.
• the activation stage is based on a colloidal, aqueous solution containing a dispersed particulate component, the particulate component containing, in addition to dispersed inorganic compounds of phosphates of polyvalent metal cations, a polymeric organic compound as a dispersing agent which is composed at least in part of styrene and/or an ⁇ -Olefin having not more than 5 carbon atoms, the polymeric organic compound additionally having units of maleic acid, its anhydride and/or its imide and the polymeric organic compound additionally having polyoxyalkylene units.
• the proportion of particulate components in the colloidal, aqueous solution is necessary for the proportion of particulate components in the colloidal, aqueous solution to be at least 4 g/kg, based on the colloidal, aqueous solution.
• the layer-forming phosphating is a process that has been practiced and intensively studied for decades for the application of crystalline anti-corrosion coatings on metallic surfaces, in particular on materials made of the metals iron, zinc and aluminium.
• Zinc phosphating which is particularly well-established for corrosion protection, takes place in a layer thickness of a few micrometers and is based on corrosive pickling of the metallic material in an acidic, aqueous composition containing zinc ions and phosphates. In the course of pickling, an alkaline diffusion layer forms on the metal surface, which extends into the interior of the solution and within which poorly soluble crystallites form, which precipitate directly at the interface with the metallic material and continue to grow there.
• Water-soluble compounds which represent a source of fluoride ions, are often added to support the pickling reaction on materials made of the metal aluminum and to mask the bath poison aluminum, which in dissolved form interferes with the formation of layers on materials made of the metal.
• the zinc phosphating is adjusted in such a way that closed, crystalline coatings are obtained with a Layer weight of at least 2 g/m 2 , especially on the zinc surfaces of the components, for good corrosion protection and paint adhesion.
• the pickling described above and the concentration of the active components in the zinc phosphating stage must be adjusted accordingly in order to ensure correspondingly high layer weights on the surfaces of the metals iron or steel, zinc and aluminum.
• Zinc phosphating always begins with activation of the metallic surfaces of the component to be phosphated.
• the wet-chemical activation is carried out conventionally by bringing them into contact with colloidal, aqueous solutions of phosphates ("activation stage"), which are immobilized on the metal surface and serve as growth nuclei for the formation of the crystalline coating within the alkaline diffusion layer in the subsequent phosphating.
• Suitable dispersions are colloidal mostly neutral to alkaline aqueous compositions based on phosphate crystallites which, in their crystal structure, exhibit only slight crystallographic deviations from the type of zinc phosphate layer to be deposited.
• bivalent and trivalent phosphates of the metals Zn, Fe, Mn, Ni, Co, Ca and Al phosphates of the metal zinc preferably being used for activation for subsequent zinc phosphating.
• An activation stage based on dispersions of bi- and trivalent phosphates requires a high level of process control in order to keep the activation performance constantly at an optimal level, especially when treating a series of metallic components.
• aqueous solution must lead to a deterioration in the activation performance. A deterioration is initially noticeable in increasing layer weights in the subsequent phosphating and finally leads to the formation of defect-rich or inhomogeneous phosphate layers.
• the layer-forming zinc phosphating is therefore a multi-stage process that is complex to control in terms of process engineering, which has also been resource-intensive to date, both in terms of the process chemicals and the energy to be expended.
• the high pickling rate means that measures to prevent or treat and dispose of Phosphating sludges must be taken, which in turn cannot do without the use of other process chemicals.
• this complex task profile can be achieved by the deposition of relatively thin phosphate coatings, for which activation using a specific polymeric dispersing agent to stabilize the colloidal component of an activation stage based on particulate phosphates is necessary, provided that it is ensured that a minimum amount of particulate components in the activation level is not undercut. Due to the extremely efficient stabilization of the particulate component that brings about the activation, the special dispersing agent ensures that high proportions of colloids can also be set in a quasi-continuous process of zinc phosphating, which surprisingly leads to improved activation of the metal surfaces and the formation of particularly thin, but more homogeneous, closed Phosphate coatings with high electrical penetration resistance.
• a metallic material has at least one surface of zinc if the metallic structure on this surface is composed of more than 50 at. % zinc up to a material penetration depth of at least one micrometer.
• metallic materials that are composed of more than 50 at Iron (ZF), aluminum (ZA) and/or magnesium (ZM) can be alloyed.
• the components treated according to the present invention can be any three-dimensional structure of any shape and design that originates from a manufacturing process, in particular semi-finished products such as strips, sheet metal, rods, pipes, etc. and composite structures assembled from the aforementioned semi-finished products, the semi-finished products preferably being assembled by gluing, Welding and / or flanging are connected to the composite structure.
• semi-finished products such as strips, sheet metal, rods, pipes, etc.
• composite structures assembled from the aforementioned semi-finished products the semi-finished products preferably being assembled by gluing, Welding and / or flanging are connected to the composite structure.
• the dispersed particulate component (a) of the colloidal, aqueous solution in activation (i) of the method according to the invention is that solids content which, after drying the retentate, undergoes ultrafiltration of a defined partial volume of the aqueous dispersion with a nominal exclusion limit of 10 kD (NMWC, Nominal Molecular Weight Cut Off) remains.
• the ultrafiltration is carried out with the addition of deionized water ( ⁇ ⁇ 1 ⁇ Scm -1 ) until a conductivity below 10 ⁇ Scm -1 is measured in the filtrate.
• an organic compound is polymeric if its weight-average molar mass is greater than 500 g/mol.
• the molar mass is determined using the molar mass distribution curve of a sample of the respective reference variable, determined experimentally at 30° C. using size exclusion chromatography with a concentration-dependent refractive index detector and calibrated against polyethylene glycol standards. The average molar mass values are evaluated computer-aided using the strip method with a third-order calibration curve.
• Hydroxylated polymethacrylate is suitable as column material and an aqueous solution of 0.2 mol/L sodium chloride, 0.02 mol/L sodium hydroxide, 6.5 mmol/L ammonium hydroxide is suitable as eluent.
• the method according to the invention is characterized in that above a quantity of particulate components of 4 g/kg in the colloidal, aqueous solution, homogeneous, closed zinc phosphate coatings grow on the surfaces of the metallic materials even at unusually low layer weights, which one with zinc phosphate coatings of the prior art Technically equivalent paint primer for subsequent electrocoating with excellent paint coverage at the same time.
• the present invention aims at the deposition of homogeneous, closed zinc phosphate coatings on the surfaces of zinc, so that according to the invention it is assumed that in process step (ii) a zinc phosphate coating with a layer weight of more than 0.5 g/ m 2 , preferably greater than 1.0 g/m 2 .
• the reduction in the layer weight also enables a shorter wet-chemical exposure time or contact time with the acidic aqueous composition of the zinc phosphating, which in turn correlates with both a lower pickling removal and a shorter overall pre-treatment time.
• a further reduction in the layer weight or the contact time in the zinc phosphating can be achieved if the proportion of the particulate components in the colloidal, aqueous solution is further increased, so that methods according to the invention are preferred in which the proportion of the particulate components of the colloidal, aqueous solution is at least 6 g/kg, particularly preferably at least 8 g/kg, particularly preferably at least 10 g/kg.
• the achievable layer weight reduction in zinc phosphating is even greater Increasing the proportion of colloids in the activation stage is only marginal and increasingly competes with disadvantages in the process control and lower colloid stability in the activation stage. It is therefore preferred to limit the proportion of the particulate components in the colloidal, aqueous dispersion to 20 g/kg, particularly preferably to 15 g/kg, in each case based on the colloidal, aqueous solution.
• the layer coverage of zinc phosphate on the surfaces of zinc should be limited to 2.0 g/m 2 for resource-saving operation of the pretreatment line.
• the layer coverage of zinc phosphate on the surfaces of zinc should be limited to 2.0 g/m 2 for resource-saving operation of the pretreatment line.
• due to the minimum amount of particulate components in the colloidal, aqueous dispersion of the activation stage a sufficiently homogeneous and closed zinc phosphate coating with excellent paint gripping behavior is provided in a subsequent electrocoating.
• the activation of the zinc surfaces in process step (i) of the process according to the invention is so effective that a further reduction in the layer thickness and thus a further reduction in material consumption in the zinc phosphating stage in process step (ii) is possible.
• process step (ii) preference is given in process step (ii) to limiting the layer weight of zinc phosphate on the surfaces of zinc to less than 1.8 g/m 2 , particularly preferably to less than 1.6 g/m 2 , particularly preferably to less than 1, 5 g/ m2 .
• the coating weight can be limited in the course of the process either by reducing the contact time with the acidic, aqueous composition for zinc phosphating in process step (ii) and/or by increasing the proportion of the particulate components of the colloidal, aqueous dispersion in process step (i). .
• the layer weight of zinc phosphate is determined within the scope of the present invention by detaching the zinc phosphate layer with aqueous 5 wt 5 min is brought into contact with a defined area of the phosphated material or component and subsequent determination of the phosphorus content in the same pickling solution with ICP-OES.
• the layer weight of zinc phosphate results from multiplying the surface-related amount of phosphorus by a factor of 6.23.
• a particular further advantage of the method according to the invention is that, in addition to zinc surfaces, the surfaces of iron and aluminum are also very effectively activated in method step (i) and in method step (ii) also very homogeneous, closed zinc phosphate coatings with a comparatively low layer weight accessible to these surfaces.
• components are preferably treated according to the invention which, in addition to zinc surfaces, also have iron and/or aluminum surfaces, in process step (ii) preferably also a zinc phosphate layer with a layer weight of less than 2.0 g/m on iron and aluminum surfaces 2 , more preferably less than 1.8 g/m 2 , more preferably less than 1.6 g/m 2 , and most preferably less than 1.5 g/m 2 , but preferably at least 0.5 g/m 2 , particularly preferably at least 1.0 g/m 2 is deposited.
• a metallic material has at least one surface made of iron or aluminum if the metallic structure on this surface is composed of more than 50 at. % iron or aluminum up to a material penetration depth of at least one micrometer.
• the proportion of condensed phosphates dissolved in water in the activation stage, based on the phosphate content of the at least one particulate compound in the colloidal aqueous solution, based on the element P is less than 0.25, particularly preferably less than 0. 20, more preferably less than 0.15 and most preferably less than 0.10.
• the proportion of condensed phosphates dissolved in water in the colloidal, aqueous solution of the method according to the invention, calculated as P is less than 100 mg/kg, particularly preferably less than 20 mg/kg, particularly preferably less than 15 mg /kg, and most preferably less than 10 mg/kg based on the colloidal aqueous solution.
• the additization of condensed phosphates can also be dispensed with entirely, so that only small amounts of condensed phosphates are found in the activation, which are also present from upstream purification stages the component to be pretreated, especially when treating a large number of components in series, reach the activation stage.
• condensed phosphates are metaphosphates and polyphosphates, preferably polyphosphates, particularly preferably pyrophosphate.
• the condensed phosphates are preferably in the form of compounds of monovalent cations, preferably selected from Li, Na and/or K, particularly preferably Na and/or K.
• the proportion of condensed phosphates can be determined analytically from the difference in the total phosphate content in the non-particulate component of the colloidal, aqueous solution with and without oxidative digestion, for example using peroxodisulphate, with the dissolved orthophosphate proportion being quantified by photometry.
• polyphosphates are used as condensed phosphates, instead of the oxidative digestion, an enzymatic digestion with a pyrophosphatase can take place.
• the non-particulate component of the colloidal, aqueous solution is the solids content of the colloidal, aqueous solution in the permeate of the ultrafiltration described above after it has been dried to constant mass at 105° C.—i.e. the solids content after the particulate component (a) has been separated off by means of ultrafiltration.
• the colloidal, aqueous solution in the activation contains at least 0.5 mmol/l, particularly preferably at least 1.0 mmol/l, particularly preferably at least 1.5 mmol/l, but preferably not more than 10 mmol /L of alkaline earth metal ions dissolved in water.
• Suitable organic complexing agents are selected from ⁇ -hydroxycarboxylic acids, which in turn are preferably selected from gluconic acid, tartronic acid, glycolic acid, citric acid, tartaric acid, lactic acid, very particularly preferably gluconic acid, and / or organophosphonic acids, which in turn are preferably selected are from etidronic acid, aminotris(methylenephosphonic acid), aminotri(methylenephosphonic acid)), phosphonobutane-1,2,4-tricarboxylic acid, diethylenetriaminepenta(methylenephosphonic acid), hexamethylenediaminetetra(methylenephosphonic acid) and/or hydroxyphosphonoacetic acid, particularly preferably etidronic acid.
• ⁇ -hydroxycarboxylic acids which in turn are preferably selected from gluconic acid, tartronic acid, glycolic acid, citric acid, tartaric acid, lactic acid, very particularly preferably gluconic acid, and / or organophosphonic acids, which
• organic complexing agents should only be added to such an extent that their amount in the colloidal, aqueous solution is preferably not more than twice, particularly preferably not more than 1.5 times, based on the amount of alkaline earth metal metal ions and most preferably is not greater than equimolar to the amount of alkaline earth metal metal ions.
• the colloidal, aqueous solution in activation (i) of the method according to the invention preferably has an alkaline pH, particularly preferably a pH above 8.0, particularly preferably above 9.0, but preferably below 11.0 , whereby compounds that influence the pH value, such as phosphoric acid, caustic soda, ammonium hydroxide or ammonia, can be used to adjust it.
• the "pH value" as used in the context of the present invention corresponds to the negative decadic logarithm of the hydronium ion activity at 20° C. and can be determined using pH-sensitive glass electrodes.
• the proportion of phosphates is contained in the at least one particulate inorganic Compound (a1), based on the dispersed particulate component (a) of the colloidal, aqueous solution, preferably at least 25% by weight, particularly preferably at least 35% by weight, particularly preferably at least 40% by weight, very particularly preferably at least 45% by weight %.
• the inorganic particulate component of the colloidal, aqueous solution is in turn that which remains when the particulate component (a) obtained from the drying of the retentate of the ultrafiltration is heated in a reaction furnace with supply of a CO 2 -free oxygen stream at 900° C. without the admixture of catalysts or other additives is pyrolyzed until an infrared sensor in the outlet of the reaction furnace delivers a signal that is identical to the CO 2 -free carrier gas (blank value).
• the phosphates contained in the inorganic particulate component are determined directly from the acid digestion as the phosphorus content by means of atomic emission spectrometry (ICP-OES) after acid digestion of the same with aqueous 10% by weight HNO 3 solution at 25° C. for 15 minutes.
• ICP-OES atomic emission spectrometry
• the active components of the colloidal, aqueous dispersion which effectively promote the formation of a closed phosphate coating on the metal surfaces and in this sense activate the metal surfaces, are, as already mentioned, composed primarily of phosphates, which in turn cause the formation of finely crystalline coatings, and are therefore at least partially selected from Hopeite, phosphophyllite, scholzite and/or hureaulite, preferably at least partially selected from hopeite, phosphophyllite and/or scholzite, more preferably at least partially selected from hopeite and/or phosphophyllite and most preferably at least partially selected from hopeite.
• Activation within the meaning of the present invention is therefore essentially based on the phosphates in particulate form contained in the activation stage.
• hopeites stoichiometrically comprise Zn 3 (PO 4 ) 2 and the variants Zn 2 Mn(PO 4 ) 3 , Zn 2 Ni(PO 4 ) 3 , Zn 2 Ni(PO 4 ) 3 containing nickel and manganese, whereas phosphophyllite consists of Zn 2 Fe(PO 4 ) 3 , scholzite consists of Zn 2 Ca(PO 4 ) 3 and hureaulite consists of Mn 3 (PO 4 ) 2 .
• the existence of the crystalline phases hopeite, phosphophyllite, scholzite and / or hureaulite in the aqueous dispersion according to the invention can, after separating the particulate component (a) by means of ultrafiltration with a nominal exclusion limit of 10 kD (NMWC, Nominal Molecular Weight Cut Off) as described above and Drying of the retentate to constant mass at 105°C can be demonstrated using X-ray diffractometric methods (XRD).
• NMWC Nominal Molecular Weight Cut Off
• Zinc phosphate coatings after activation are preferred if in the process according to the invention in the colloidal, aqueous dispersion at least 20% by weight, particularly preferably at least 30% by weight, particularly preferably at least 40% by weight, of zinc in the inorganic particulate component of the colloidal, aqueous Solution based on the phosphate content of the inorganic particulate component, calculated as PO 4 , are included.
• activation within the meaning of the present invention should preferably not be achieved by means of colloidal solutions of titanium phosphates, since otherwise the layer-forming zinc phosphating on iron, in particular steel, cannot be reliably achieved.
• the proportion of titanium in the inorganic particulate component of the colloidal, aqueous solution is less than 0.01% by weight, particularly preferably less than 0.001% by weight, based on the colloidal, aqueous solution.
• the colloidal, aqueous solution of activation stage (i) contains less than 10 mg/kg, particularly preferably less than 1 mg/kg, of titanium in total.
• the activation stage in the method according to the invention can also be characterized by its D50 value, above which the activation performance decreases significantly.
• the D50 value of the colloidal, aqueous solution is preferably below 1 ⁇ m, particularly preferably below 0.4 ⁇ m.
• the D50 value denotes the particle diameter which 50% by volume of the particulate components contained in the colloidal, aqueous solution do not exceed.
• the polymeric organic compounds (a2) used as dispersing agents and containing polyoxyalkylene units are at least partly composed of styrene and/or an ⁇ -olefin having not more than 5 carbon atoms and maleic acid, its anhydride and/or its imide, and cause the extremely high stability of the colloidal, aqueous solution in the activation stage of the method according to the invention.
• the ⁇ -olefin is preferably selected from ethene, 1-propene, 1-butene, isobutylene, 1-pentene, 2-methylbut-1-ene and/or 3-methylbut-1-ene and particularly preferably selected from isobutylene. It is clear to the person skilled in the art that the polymeric organic compounds (a2) contain these monomers as structural units in unsaturated form covalently linked to one another or to other structural units.
• Suitable commercially available representatives are, for example, Dispex ® CX 4320 (BASF SE) a maleic acid-isobutylene copolymer modified with polypropylene glycol, Tego ® Dispers 752 W (Evonik Industries AG) a maleic acid-styrene copolymer modified with polyethylene glycol or Edaplan ® 490 (Münzing Chemie GmbH) modified a maleic acid-styrene copolymer with EO/PO and imidazole units.
• preference is given to those polymeric organic compounds (a2) which are composed at least partly of styrene.
• the polymeric organic compounds (a2) used as dispersants have polyoxyalkylene units which are preferably built up from 1,2-ethanediol and/or 1,2-propanediol, more preferably both from 1,2-ethanediol and from 1,2 -propanediol, the proportion of 1,2-propanediols in the total of the polyoxyalkylene units preferably being at least 15% by weight, but particularly preferably not exceeding 40% by weight, based on the total of the polyoxyalkylene units.
• the polyoxyalkylene units are preferably contained in the side chains of the polymeric organic compounds (a2).
• a proportion of the polyoxyalkylene units in the total of the polymeric organic compounds (a2) of preferably at least 40% by weight, particularly preferably at least 50% by weight, but preferably not more than 70% by weight, is advantageous for the dispersibility.
• the organic polymeric compounds (a2) have additionally also imidazole units, preferably such that the polyoxyalkylene units of the polymeric organic compounds (a2) are at least partially end-capped with an imidazole group, so that in the preferred embodiment there are terminal imidazole groups in the polyoxyalkylene side chain, the covalent
• the polyoxyalkylene units are preferably linked to the imidazole group via a nitrogen atom of the heterocycle.
• the amine number of the organic polymeric compounds (a2) is at least 25 mg KOH/g, particularly preferably at least 40 mg KOH/g, but preferably less than 125 mg KOH/g, particularly preferably less than 80 mg KOH / g, so that in a preferred embodiment all of the polymeric organic compounds in particulate component (a) also have these preferred amine numbers.
• the amine number is determined in each case by weighing approximately 1 g of the respective reference quantity - organic polymeric compounds (a2) or all of the polymeric organic compounds in the particulate component - in 100 ml of ethanol, using 0.1 N HCl standard solution against the indicator bromophenol blue is titrated until the color changes to yellow at a temperature of the ethanolic solution of 20 °C.
• the amount of standard HCl solution consumed in milliliters multiplied by the factor 5.61 divided by the exact mass of the sample in grams corresponds to the amine number in milligrams of KOH per gram of the respective reference value.
• the presence of maleic acid insofar as it is a component of the organic polymeric compound (a2) as the free acid and not in the form of the anhydride or imide, can impart increased water solubility of the dispersing assistant, particularly in the alkaline range. It is therefore preferred that the polymeric organic compounds (a2), preferably also all of the polymeric organic compounds in the particulate component (a), have an acid number according to DGF CV 2 (06) (as of April 2018) of at least 25 mg KOH/g but preferably less than 100 mg KOH/g, more preferably less than 70 mg KOH/g to ensure a sufficient number of polyoxyalkylene units.
• the polymeric organic compounds (a2) preferably also all of the polymeric organic compounds in the particulate component (a), have a hydroxyl number of less than 15 mg KOH/g, particularly preferably less than 12 mg KOH/g, particularly preferably less than 10 mg KOH/g, determined in each case according to method A of 01/2008:20503 from European Pharmacopoeia 9.0.
• the proportion of the polymeric organic compounds (a2), preferably all of the polymeric organic Compounds in the particulate component (a), based on the particulate component (a), is at least 3% by weight, particularly preferably at least 6% by weight, but preferably does not exceed 15% by weight.
• dispersed particulate component (A) and the at least one particulate inorganic compound (A1) or polymeric organic compound (A2) as were given above for the colloidal, aqueous solution.
• the dilution is preferably carried out with deionized water ( ⁇ 1 ⁇ Scm -1 ), particularly preferably with industrial water, in order to make the process according to the invention as resource-saving as possible shape.
• deionized water ⁇ 1 ⁇ Scm -1
• Process water in the light of the technical application on which it is based contains at least 0.5 mmol/L of alkaline earth metal ions.
• a thickener according to component (B) gives the aqueous dispersion, in combination with its particulate component, thixotropic flow behavior and thus helps counteract the irreversible formation of agglomerates in the particulate component of the dispersion, from which primary particles can no longer be separated.
• the addition of the thickener should preferably be controlled in such a way that the aqueous dispersions in the shear rate range from 0.001 to 0.25 reciprocal seconds have a maximum dynamic viscosity at a temperature of 25° C.
• the viscosity over the specified shear rate range can be determined using a plate/cone viscometer with a cone diameter of 35 mm and a gap width of 0.047 mm.
• To determine this thickening property prepare the mixture with water in such a way that the appropriate amount of the polymeric chemical compound is added to the water phase while stirring at 25 °C and the homogenized mixture is then freed of air bubbles in an ultrasonic bath and left to stand for 24 hours. The viscosity reading is then read immediately within 5 seconds after application of 60 rpm shear by spindle number 2.
• An aqueous dispersion according to the invention preferably contains a total of at least 0.5% by weight, but preferably not more than 4% by weight, particularly preferably not more than 3% by weight, of one or more thickeners according to component (B), with further preference the total proportion of polymeric organic compounds in the non-particulate component of the aqueous dispersion is 4% by weight (based on the dispersion). exceeds.
• the non-particulate component is the solids content of the aqueous dispersion in the permeate of the ultrafiltration already described after it has been dried to constant mass at 105° C.—ie the solids content after the particulate component has been separated off by means of ultrafiltration.
• the thickener according to component (B) is initially preferably selected from polymeric organic compounds, which in turn are preferably selected from polysaccharides, cellulose derivatives, aminoplasts, polyvinyl alcohols, polyvinylpyrrolidones, polyurethanes and/or urea urethane resins, and particularly preferably from urea urethane resins.
• a urea urethane resin as a thickener according to component (B) of the preferred inventive method for providing a colloidal aqueous solution starting from the aqueous dispersion is a mixture of polymeric compounds resulting from the reaction of a polyfunctional isocyanate with a polyol and a mono- and / or diamine emerges.
• the urea urethane resin is derived from a polyhydric isocyanate, preferably selected from 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2(4),4-trimethyl-1,6-hexamethylene diisocyanate, 1,10- Decamethylene diisocyanate, 1,4'-cyclohexylene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate and mixtures thereof, p- and m-xylylene diisocyanate, and 4-4'-diisocyanatodicyclohexylmethane, particularly preferably selected from 2,4-toluene diisocyanate and/or m-xylylene diisocyanate.
• a polyhydric isocyanate preferably selected from 1,4-te
• the urea-urethane resin is derived from a polyol selected from polyoxyalkylene diols, particularly preferably from polyoxyethylene glycols, which in turn are preferably composed of at least 6, particularly preferably at least 8, particularly preferably at least 10, but preferably less than 26, particularly preferably less than 23 oxyalkylene units.
• Urea urethane resins which are particularly suitable and therefore preferred according to the invention can be obtained by first reacting a diisocyanate, for example toluene-2,4-diisocyanate, with a polyol, for example a polyethylene glycol, to form NCO-terminated urethane prepolymers, then with a primary monoamine and/or with a primary diamine , For example, m-xylylenediamine, is further implemented.
• a diisocyanate for example toluene-2,4-diisocyanate
• a polyol for example a polyethylene glycol
• urea-urethane resins which have neither free nor blocked isocyanate groups.
• a component of the aqueous dispersion from which the colloidal, aqueous solution of the process according to the invention can be obtained by dilution such urea-urethane resins promote the formation of loose agglomerates of primary particles, which in turn are stabilized in the aqueous phase and protected against further agglomeration to such an extent that the sedimentation of the particulate component in the aqueous dispersion is largely prevented.
• urea-urethane resins which have neither free or blocked isocyanate groups nor terminal amine groups are preferably used as component (B).
• the thickener according to component (B), which is a urea urethane resin therefore has an amine number of less than 8 mg KOH/g, particularly preferably less than 5 mg KOH/g, particularly preferably less than 2 mg KOH/g. g, determined in each case by the method described above for the organic polymeric compound (A2).
• an aqueous dispersion is accordingly required for provision the colloidal, aqueous solution of activation, in which all of the polymeric organic compounds in the non-particulate component preferably have an amine number of less than 16 mg KOH/g, particularly preferably less than 10 mg KOH/g, particularly preferably less than 4 mg KOH/g.
• the urea-urethane resin has a hydroxyl number in the range from 10 to 100 mg KOH/g, particularly preferably in the range from 20 to 60 mg KOH/g, determined by method A of 01/2008:20503 from European Pharmacopoeia 9.0.
• a weight-average molar mass of the urea-urethane resin in the range from 1000 to 10000 g/mol, preferably in the range from 2000 to 6000 g/mol is advantageous according to the invention and therefore preferred, in each case determined experimentally as above in connection with the definition of a polymeric compound according to the invention described.
• the pH of the dispersion for providing the colloidal, aqueous solution for activating the method according to the invention is usually in the range of 6.0-9.0 without the addition of auxiliaries, and such a pH range is therefore preferred according to the invention.
• the pH of the aqueous dispersion possibly also as a result of the addition of alkaline-reacting compounds, is above 7.2, particularly preferably above 8.0.
• the alkalinity of the aqueous dispersion according to the invention is ideally limited, since some polyvalent metal cations have an amphoteric character and can therefore be leached out of the particulate component at higher pH values, so that the pH value of the aqueous dispersion is preferably below 10 and in particular preferably below 9.0.
• the aqueous dispersion can also contain auxiliaries, for example selected from preservatives, wetting agents and defoamers, which are present in the amount required for the particular function.
• auxiliaries for example selected from preservatives, wetting agents and defoamers, which are present in the amount required for the particular function.
• an alkaline compound is water-soluble (water solubility: at least 10 g per kilogram of water with ⁇ 1 ⁇ Scm -1 ) and has a pK B value for the first protonation stage above 8.0.
• the resource-saving process management according to the present invention is particularly useful in the zinc phosphating of components in series, ie during ongoing operation of a pre-treatment line for zinc phosphating.
• a large number of concrete components which are at least partially composed of a metallic material which has at least one surface made of zinc are therefore treated in series.
• a pretreatment in series is when the components of the series are first activated according to the method according to the invention and then zinc phosphated and are brought into contact with baths provided in system tanks for activation and zinc phosphating, the individual components being brought into contact one after the other and is therefore separated in time.
• the system tank is the container that contains the colloidal, aqueous solution for the purpose of activation or the acidic, aqueous composition for the purpose of phosphating.
• a rinsing step between the activation (i) and the zinc phosphating (ii) in order to reduce the carryover of alkaline components into the acidic aqueous composition for zinc phosphating, but a rinsing step is preferably omitted in order to obtain the activation of the metallic surfaces completely.
• a rinsing step is used exclusively for the complete or partial removal of soluble residues, particles and active components, which are carried over from a previous wet-chemical treatment step adhering to the component, from the component to be treated, without the rinsing liquid itself containing active components based on metallic or semi-metallic elements, which are already consumed by the mere contact of the metallic surfaces of the component with the rinsing liquid.
• the rinsing liquid can only be city water or deionized water or, if necessary, it can also be a rinsing liquid which contains surface-active compounds to improve the wettability with the rinsing liquid.
• the phosphating in step (ii) by bringing the surfaces into contact with a acidic aqueous composition containing 5 - 50 g/l of phosphate ions, 0.3 - 3 g/l of zinc ions and a quantity of free fluoride.
• the amount of phosphate ions includes the orthophosphoric acid and the anions of the salts of orthophosphoric acid dissolved in water, calculated as PO 4 .
• a quantity of free fluoride or a source of free fluoride ions is essential for the process of layer-forming zinc phosphating, insofar as components comprising surfaces of zinc as well as surfaces of iron or aluminum are to be zinc-phosphated in a layer-forming manner, as is the case, for example, in the zinc phosphating of automobile bodies, which are at least partially made of aluminum is required.
• the amount of free fluoride in the acidic aqueous composition is at least 0.5 mmol/kg, particularly preferably at least 2 mmol/kg.
• the concentration of free fluoride should not exceed values above which the phosphate coatings mainly have adhesions that can be easily wiped off, since this cannot be avoided even by a disproportionately increased amount of particulate components in the colloidal, aqueous solution of the activation. It is therefore also advantageous for economic reasons and therefore preferred if, in the method according to the invention based on activation (i) followed by zinc phosphating (ii), the concentration of free fluoride in the acidic aqueous composition of zinc phosphating is below 15 mmol/kg, particularly preferably below 10 mmol/kg and particularly preferably below 8 mmol/kg.
• the amount of free fluoride is to be determined potentiometrically at 20 °C in the respective acidic aqueous composition after calibration with fluoride-containing buffer solutions without pH buffering using a fluoride-sensitive measuring electrode.
• Suitable sources for free fluoride ions are hydrofluoric acid and its water-soluble salts, such as ammonium bifluoride and sodium fluoride, and complex fluorides of the elements Zr, Ti and/or Si, in particular complex fluorides of the element Si.
• the source of free fluoride in a phosphating according to the present invention is therefore preferably selected from hydrofluoric acid and its water-soluble salts and/or complex fluorides of the elements Zr, Ti and/or Si.
• Hydrofluoric acid salts are water-soluble in the context of the present invention if their solubility in deionized water ( ⁇ 1 ⁇ Scm ⁇ 1 ) at 60° C. is at least 1 g/L calculated as F.
• the source of free fluoride is at least partially selected from complex ones in processes according to the invention in which zinc phosphating takes place in step (ii).
• Fluorides of the element Si in particular from hexafluorosilicic acid and its salts.
• Those skilled in the art of phosphating understand the formation of specks as the phenomenon of local deposition of amorphous, white zinc phosphate in an otherwise crystalline phosphate layer on the treated zinc surfaces or on the treated galvanized or alloy-galvanized steel surfaces.
• the preferred pH of the acidic aqueous composition is above 2.5, particularly preferably above 2.7, but preferably below 3.5, particularly preferably below 3.3.
• the proportion of the free acid in points in the acidic aqueous composition of the zinc phosphating in process step (ii) is preferably at least 0.4, but preferably not more than 3.0, particularly preferably not more than 2.0.
• the percentage of free acid in points is determined by diluting a 10 ml sample volume of the acidic aqueous composition to 50 ml and titrating with 0.1 N sodium hydroxide solution to pH 3.6. The consumption of ml of sodium hydroxide indicates the number of free acid points.
• the usual additization of zinc phosphating can also be carried out in an analogous manner within the scope of the present invention, so that the acidic aqueous composition in process step (ii) contains the usual accelerators such as hydrogen peroxide, nitrite, hydroxylamine, nitroguanidine and/or N-methylmorpholine N-oxide and additionally cations of the metals manganese, calcium and/or iron in the form of water-soluble salts, which have a positive influence on the layer formation.
• An embodiment in which less than 10 ppm of nickel and/or cobalt ions are contained in the acidic aqueous composition of the zinc phosphating in process step (ii) is particularly preferred from an ecological point of view.
• zinc phosphating follows with or without intermediate rinsing and/or drying step, but preferably with a rinsing step but without a drying step, a dip coating, particularly preferably an electro-dip coating, particularly preferably a cathodic electro-dip coating, which preferably, in addition to the dispersed resin, which preferably comprises an amine-modified polyepoxide, water-soluble or water-dispersible Contains salts of yttrium and/or bismuth.

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• 2020
  • 2020-08-11 EP EP20190493.5A patent/EP3954805A1/fr not_active Withdrawn
• 2021
  • 2021-06-28 CN CN202180056390.2A patent/CN116034185A/zh active Pending
  • 2021-06-28 JP JP2023509851A patent/JP2023538000A/ja active Pending
  • 2021-06-28 EP EP21735717.7A patent/EP4196625A1/fr active Pending
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  • 2021-06-28 WO PCT/EP2021/067630 patent/WO2022033759A1/fr unknown
  • 2021-06-28 KR KR1020237008121A patent/KR20230050387A/ko unknown
• 2023
  • 2023-02-07 US US18/165,696 patent/US20230175138A1/en active Pending

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