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
  • C23C22/05—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
• • 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
• • 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
  • C23C22/361—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 titanium, zirconium or hafnium 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
  • 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
  • C23C22/73—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
  • C23C22/82—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
  • C23C22/82—After-treatment
  • C23C22/83—Chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
  • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling

Definitions

• the invention relates to a steel sheet with a conversion layer, a method for producing a conversion-coated steel sheet and a treatment agent for applying a conversion layer on a steel sheet.
• the metallic surface is provided with a coating of another, usually less noble, metal (such as zinc and chromium). So it is e.g. known to coat steel sheets with zinc or chromium or with tin (which, however, is nobler compared to steel).
• tinplate very extensively tinned Feinstbleche (tinplate) are used. Tinplates are characterized by a very good corrosion resistance and a good forming behavior and their weldability and are therefore very well suited for the production of packaging, such. Beverage cans.
• Tinplate has excellent properties as a food packaging material and has been manufactured and processed for many decades for this purpose.
• tin which is the anticorrosion coating on tinplate
• electrolytically plated chromium plated steel sheets are known as Tin Free Steel (TFS) or Electrolytic Chromium Coated Steel (ECCS)
• TFS Tin Free Steel
• ECCS Electrolytic Chromium Coated Steel
• these tin-free steel sheets are distinguished by good adhesion to paints or organic protective coatings (for example PP or PET), but on the other hand have considerable disadvantages in carrying out the coating process because of the toxic and health-endangering properties of the chromium-VI-containing materials used for coating ,
• conversion coatings are often applied to the steel sheet surface.
• the targeted generation of a conversion layer on a steel sheet prevents corrosion of the steel sheet or slows them at least strong.
• Conversion layers are non-metallic, very thin layers on a metal surface, which are usually produced by chemical reaction of an aqueous treatment solution with the metallic substrate. Conversion coatings ensure a very effective corrosion protection, a good primer for paints and plastics, especially for thin steel sheets (fine plates with thicknesses in the range of 0.1 to 0.5 mm) and they reduce surface friction and abrasion.
• Electrolytic methods for applying conversion layers to steel sheets are known from the prior art. Conversion views were often generated with chromium electrolytes based on the carcinogenic chromium (VI) oxide. However, chromium (VI) -containing conversion layers are used less and less frequently due to legal prohibitions. Alternatives to the classic chromium (VI) electrolyte are treatments based on chromium (III) oxide or complex fluorides (titanium, zirconium compounds). Another possibility for producing a conversion layer is the phosphating by means of aqueous phosphate solutions.
• From the DE 101 61 383 A1 discloses a process for coating metallic surfaces, including steel surfaces, with an aqueous composition free of chromium (VI) compounds, the aqueous composition containing, in addition to the water solvent, at least one organic film former containing a water-soluble or water-dispersed polymer containing cations and / or hexa- or tetrafluoro complexes of cations selected from Ti, Zr, Hf, Si, Al and B, at least one inorganic compound in particle form with a particle diameter of 0.005 ⁇ m to 0.2 ⁇ m and optionally a silane and / or siloxane and also optionally contains a corrosion inhibitor.
• VI chromium
• chromium-free means for producing conversion coatings on metal contain either film formers or organic solvents.
• Film formers are typically polymers which impart various useful properties, such as adhesiveness, to the conversion layer.
• these polymers require an increased effort in applying the funds and they make the means more expensive.
• the solvents contained in conventional, chromium-free conversion-coating agents are generally more expensive than water, represent to some extent a health impairment in applying the conversion layer and in most cases belong to the so-called VOC (Volatile Organic Compound) Environmental reasons should be avoided.
• the object of the present invention is therefore to provide a chromium-free agent for producing conversion coatings on steel sheets.
• the invention is furthermore intended to show steel sheets with a chromium-free conversion layer and a method for their production which can be produced as inexpensively as possible and can be used as a substitute for tin-free steel sheet (TFS or ECCS) and tinplate, and in particular with regard to corrosion resistance and adhesiveness for paints or organic coatings should be comparable to tinplate or tin-free steel sheet.
• the conversion layer preferably consists of one of the components i) to iii) or of a mixture of these components, more preferably of a mixture of components i) and ii) or a mixture of all three components i), ii) and iii).
• a metal-coated or uncoated steel sheet (black sheet) is used, the surface is degreased in a first process step, then rinsed with water or another rinsing liquid and finally in a further step, a wet film of a conversion layer is applied by at least one degreased Surface of the steel sheet, a wet film of a chromium-free treatment solution consisting solely of inorganic components, is applied, wherein the wet film of the conversion layer of water-dissolved components is produced and the components are selected from hexafluorotitanate, zinc phosphate and / or iron phosphate, phosphoric acid, and / or a mixture of these components, with the proviso that the components contain no organic substances and also no inorganic particles with an average particle diameter of more than 0.005 microns.
• the volume of the wet film is preferably in the range of 1 ml / m 2 to 10 ml / m 2 .
• the chromium-free treatment solution consists only of water and one of the components hexafluorotitanate, zinc phosphate and / or iron phosphate or phosphoric acid, or a mixture of these components, more preferably from a mixture of the components hexafluorotitanate and zinc phosphate or a mixture of the components hexafluorotitanate, zinc phosphate and phosphoric acid.
• the solvent evaporates, so that the dried conversion layer consists in these preferred embodiments only of the effective components of the chromium-free treatment solution, ie hexafluorotitanate, zinc phosphate and / or iron phosphate and phosphoric acid, or a mixture of these active components.
• the steel of the steel sheet may, for example, be a ferritic steel or else a multiphase steel having a plurality of structural constituents, in particular ferrite, martensite, bainite and / or retained austenite.
• Such multiphase steels are characterized by a high strength of more than 500 MPa with simultaneously good elongation at break of more than 10%.
• the grades of the steel sheet defined in DIN EN 10202: 2001: "Cold-rolled packaging sheet products (electrolytically tinned and chromium-plated)" are preferably observed. In this standard are u.a. Analysis and mechanical characteristics of the steel defined.
• the grades are in particular between TS230 (soft hood furnace grade, yield strength 230 MPa) to TH620 (DO, 620MPa).
• the steel sheet can also be a metal-coated steel sheet, for example an electrolytically tin-plated steel sheet.
• the steel sheet which is preferably in strip form, is moved at a belt speed of preferably more than 200 m / min and up to 750 m / min and subjected to an electrochemical pretreatment.
• the moving steel sheet is first cleaned and degreased.
• the cleaning and degreasing is expediently carried out in an electrolyte with switching of the steel sheet as a cathode.
• Degreasing is expedient because the cold-rolled and recrystallization annealed steel sheet is usually post-rolled or dressed after recrystallization annealing, for example when wet-rolling with a water-oil suspension or even during dry raking the steel sheet surfaces are contaminated by oil, iron abrasion, soaps and other contaminants. This contamination is eliminated by the cleaning step.
• the steel sheet can, for example, be passed through a cleaning tank with an alkaline sodium or potassium hydroxide solution.
• concentration of the alkaline degreasing agent is preferably between 20 and 100 g / l at bath temperatures of 20-70 ° C.
• a degreasing of the black plate is expediently carried out in two steps, wherein in a first step a dipping method and in the second step an electrolytic method with current densities of 2 to 30 A / dm 2 is performed. After degreasing, each band side of the black plate is rinsed, for example, by a triple cascade rinsing with 10-30 m 3 / h of water.
• Removal of oxide remnants may, if necessary, be accomplished by passing the blackplate strip into further cleansing tanks having a hydrochloric acid or sulfuric acid pickling at a concentration of, for example, 10 to 120 g / l in two consecutive dives, followed by a dive with a dive.
• the temperatures of the pickling solution and the rinsing water are typically between 20 and 60 ° C.
• a further electrochemical treatment of the steel sheet can be carried out to form a homogeneous steel surface, which forms a good adhesion base for a conversion layer.
• the steel sheet is connected as an anode and passed through an alkaline electrolyte.
• the alkaline electrolyte may, for example, be a sodium hydroxide solution or a sodium carbonate solution (Na 2 CO 3 ).
• the steel sheet is rinsed with water or other rinsing liquid and then dried.
• the drying can be carried out, for example, in a continuous furnace or with a blowing device, with which a laminar flow of hot air is blown onto the surface of the moving steel sheet.
• the application of the conversion layer to at least one surface of the steel sheet is a wet film of an aqueous, chromium-free and based solely on inorganic components
• Treatment solution applied to the electrochemically pretreated and dried surface of the steel sheet This can conveniently be done in a no-rinse process in which rinsing is omitted after the application of the wet layer.
• the aqueous treatment solution which forms the conversion coating can, for example, be applied to the surface of the steel sheet with a roller coater or sprayed with spray nozzles, for example with a rotary sprayer.
• the conversion layer formed thereby is dried.
• the steel sheet can, for example, be guided through a belt dryer in order to dry the wet film of the conversion layer.
• the drying is preferably carried out at temperatures of 50-250 ° C.
• the desired dry coverage of the conversion layer can be adjusted by the amount of aqueous treatment solution supplied per unit time in the application step. If necessary, the basis weight of the applied conversion layer can be adjusted before drying by squeezing off excess treatment solution.
• the surface of the dry conversion layer can optionally be aftertreated with dioctyl sebacate (DOS), acetyltributylcitrate (ATBC), butyl stearate (BSO) or polyalkylene glycol, in particular polyethylene glycol (PEG, preferably with a molecular weight of 6000 g / mol), or combinations thereof.
• DOS dioctyl sebacate
• ATBC acetyltributylcitrate
• BSO butyl stearate
• PEG polyethylene glycol
• the effectiveness of the treatment solutions and the properties of the conversion layers are dependent on the concentration of the respective components in the aqueous treatment solution and on the volume coverage of the aqueous treatment solution on the steel sheet surface.
• a preferred dry coverage based on titanium has in the range from 1 mg / m 2 to 50 mg / m 2 , preferably in the range from 10 mg / m 2 to 40 mg / m 2 .
• a preferred dry coating based on phosphate ions in the range of 10 mg / m 2 to 1000 mg / m 2 and preferably in the range of 100 mg / m 2 to 400 mg / m 2 .
• the specified concentrations of the components of the treatment solutions refer to the treatment solution itself and not to optionally used batch solutions of higher concentration. All concentrations are based on the weight fractions of the active components in the aqueous treatment solution, regardless of whether the raw materials used even in dilute form, for. B. as aqueous solutions, templates.
• test sheets in the form of black sheets (uncoated, cold-rolled steel sheets) with a thickness of 0.27 mm were used.
• the resulting overlay of the conversion layer (dry overlay of the treatment solution) is shown in Table 1.
• the measured values of the cyclic voltammetry of Table 1 show relatively high values in the case of conversion layers of hexafluorotitanate, which indicates permeability of the layer.
• the conversion layers which contain phosphates (zinc phosphate, iron phosphate), show consistently low measured values, which suggests a more covering and denser layer. In terms of oxidability, the phosphate-containing conversion layers therefore have better properties and in particular a higher corrosion resistance.
• the combination of hexafluorotitanate or hexafluorotitanic acid with zinc phosphate shows surprisingly good results in terms of zyklovoltammetrischen measurements (10 uA / cm 3 - 50 uA / cm 3 ).
• the positive properties of the titanium-containing conversion layers and of the phosphate-containing conversion layers can be combined if the aqueous treatment solution is produced from a mixture of hexafluorotitanate or hexafluorotitanic acid and zinc phosphate and / or iron phosphate with water as solvent, in particular with proportions by weight for the hexafluorotitanic acid of 1 to 10%. and for the zinc phosphate and / or iron phosphate of (in total) 1 to 10%.
• Phosphoric acid may also be added to this preferred mixture, for example in a proportion by weight of from 1 to 10%.
• the addition of phosphoric acid has the advantage that the zinc phosphate can be solved with it.
• gold lacquer AN 101 597 with a run of 5 g / m 2 were applied to the dried conversion layers; gold lacquer BPA ni Metlac 816,714 with a run of 5 g / m 2; gold lacquer GL 300 MF with a run of 5 g / m 2 , white varnish BPA ni Valspar R 1016 with an application of 15 g / m 2 ) and the coated test panels were subjected to stress tests (forming and sterilization) and tested with the crosshatch test and the Erichsen graduation to evaluate the paint adhesion.
• a point rating system was used in which, depending on the quality of the paint adhesion, points from 0 (no adhesion) to 7 (optimal adhesion) have been awarded.
• the points that resulted for a conversion layer for the different paints were added and the sum of this addition is listed in Table 2 . The larger the sum value, the better the adhesion of the respective conversion layer for organic paints.
• Lacquer adhesion results were compared with comparative samples of conventional tin-free steel sheets (ECCS and TFS) and with steel sheets coated with the commercially available Henkel "Bonderite®” agent.
• the conventional tin-free steel sheets (ECCS or TFS) have a total score of 115 and the "Bonderite®" -coated steel sheets have achieved overall scores in the range of 88 to 118, depending on the edition.
• a preferred range of the (titanium-related) edition of the conversion layer is therefore in the range of 1 to 50 mg / m 2 , more preferably 3 to 40 mg / m 2 , in particular 10 to 40 mg / m 2 or even 20 to 40 mg / m 2 or 15 to 30 mg / m 2 .
• a preferred range of the conversion of the conversion layer based on phosphate (PO 4 ) is therefore in the region of 10 to 500 mg / m 2 , more preferably 20 to 400 mg / m 2 , in particular 50 to 300 mg / m 2 , or else 100 to 250 mg / m 2 or 150 to 300 mg / m 2 .
• the formability of the painted sample sheets was investigated.
• the coated sample plates were formed by deep drawing to ⁇ -2 wells. It has been shown that even at high conversions, the conversion layers of hexafluorotitanate (hexafluorotitanic acid) are the most advantageous. However, it has been shown that the titanium-containing conversion layers with coating coverings> 40 mg / m 2 do not give good results in the forming test, which is why coating runs of less than 40 mg / m 2 are preferred for the titanium-containing conversion layers.
• a coating with the active component titanium in the range of titanium deposits of 1 mg / m 2 to 50 mg / m 2 , preferably in the range of 10 mg / m 2 to 40 mg / m 2 gives good results.
• the element zinc has a positive effect on the properties and shows good results up to a zinc concentration of 5%.
• the process according to the invention can be carried out without major installation effort into an existing coating installation, e.g. be integrated into a coil coating plant for the production of ECCS (or TFS).
• the belt speed in such belt coating systems is typically 80-600 m / min.
• the inventive method has the advantages of a chromium-free, on inorganic components based and thus environmentally friendly and not harmful to health and very inexpensive conversion coating on steel sheets.
• the steel sheets treated by the method according to the invention are outstandingly suitable for the production of packaging, in particular cans, and can therefore replace the tinplates and tin-free steel sheets (TFS or ECCS) conventionally used as packaging steel.
• the black plates coated according to the invention with a conversion layer (cold-rolled steel plates without metal coating) are comparable with tinplate in terms of their corrosion resistance and have similarly good adhesion properties for organic lacquers and plastic coatings (for example of PP or PET), such as the tin-free steel sheets (TFS or ECCS ).

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• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Electrochemistry (AREA)
• Chemical Treatment Of Metals (AREA)

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• 2017
  • 2017-07-28 DE DE102017117080.4A patent/DE102017117080A1/de not_active Withdrawn
• 2018
  • 2018-03-07 EP EP18160491.9A patent/EP3434807A1/fr not_active Withdrawn
  • 2018-03-14 AU AU2018201806A patent/AU2018201806A1/en not_active Abandoned
  • 2018-03-26 CA CA2999304A patent/CA2999304A1/fr active Pending
  • 2018-04-19 BR BR102018007860-7A patent/BR102018007860A2/pt not_active Application Discontinuation
  • 2018-05-02 JP JP2018088538A patent/JP2019026929A/ja active Pending
  • 2018-05-04 US US15/971,430 patent/US20190032222A1/en not_active Abandoned
  • 2018-07-20 KR KR1020180084609A patent/KR20190013516A/ko not_active Application Discontinuation
  • 2018-07-23 CN CN201810812570.9A patent/CN109306483A/zh active Pending

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