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
  • C23C22/34—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
  • C23C22/367—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 alkaline earth metal 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
  • C23C22/368—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 magnesium 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
  • C23C22/40—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 molybdates, tungstates or vanadates
  • C23C22/44—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 molybdates, tungstates or vanadates containing also fluorides or complex fluorides

Definitions

• the present invention is directed to an aqueous, acidic conversion coating composition that is characterized as being free of chromium. More particularly, the present invention is directed to an aqueous, acidic conversion coating composition comprising at least one water-soluble polyphosphonic acid and at least one tungstate salt.
• conversion coating and " conversion treatment” refer to a treatment of the surface of a substrate which causes the surface material to be chemically converted to a different material.
• a metal or alloyed surface is chemically converted to provide a tightly adherent coating, all or part of which consists of a stabilized form - for instance an oxidized form - of the substrate metal.
• Such chemical conversion coatings can demonstrate high corrosion resistance as well as providing a strong bonding affinity for subsequent coating layers, such as paints, inks and varnishes.
• US Patent No. 5,468,307 A describes an aqueous chemical bath for producing an oxide-film cobalt conversion coating on an aluminium or aluminium alloy substrate, said chemical bath being prepared by reacting: (a) in the presence of an oxidizer; (b) a cobalt (II) salt of which the counter anion is chloride, bromide, nitrate, cyanide, thiocyanate, phosphate, sulphate, acetate or carbonate; (c) a nitrate salt of lithium, potassium, sodium, calcium or magnesium; and, (d) ammonium acetate, wherein: i) the concentration of said cobalt (II) salt is from 0.01 moles per liter to the saturation limit of the final solution; ii) the concentration of said metal nitrate salt is from 0.03 to 2.5 moles per liter of final solution; and, iii) the concentration of said ammonium acetate is from 0.06 to 6.0 moles per liter of final solution.
• U.S. Pat. No. 6,328,874 discloses a method for protecting an aluminum surface from corrosion comprising, contacting the aluminum surface with a mixture of water, a multifunctional polymeric organic acid and a monomer of an intrinsically conductive polymer and imposing an electrical potential between the aluminum surface as the anode and a cathode, where the electrical potential is sufficient to polymerize the monomer of the intrinsically conductive polymer and to form aluminum oxide, thereby forming on the aluminum surface a coating of the multifunctional polymeric organic acid salt of the intrinsically conductive polymer intermixed with aluminum oxide.
• the composition has a pH of from 1 to 3 and comprises, based on the weight of the composition:
• component iv) said at least one tungstate salt may be selected from the group consisting of: sodium orthotungstate (Na 2 WO 4 ); sodium metatungstate (Na 6 H 2 W 12 O 40 ); potassium orthotungstate (K 2 WO 4 ); and, potassium metatungstate (K 6 H 2 W 12 O 40 ).
• conversion coating composition refers to that composition which actually contacts the aluminium or aluminium alloy substrate. As is known in the art, such contacting typically occurs in a so-called “ bath " which is shaped, sized and disposed to enable at least part of the substrate to be immersed therein.
• the bath should moreover be sized to allow for movement of the composition around and throughout the loaded substrate, which movement can be further enhanced with recirculation and / or ultrasonics.
• the pH of the composition within the bath, the temperature of the bath, and contact time of the substrate are result effective variables which should be monitored either manually or automatically, whenever possible.
• Viscosities of the conversion coating compositions may be determined using the Brookfield Viscometer, Model RVT at standard conditions of 20°C. and 50% Relative Humidity (RH).
• the viscometer is calibrated using silicone oils of known viscosities, which vary from 5,000 cps to 50,000 cps.
• a set of RV spindles that attach to the viscometer are used for the calibration.
• Measurements of the conversion coating compositions are done using the No. 6 spindle at a speed of 20 revolutions per minute for 1 minute until the viscometer equilibrates. The viscosity corresponding to the equilibrium reading is then calculated using the calibration.
• alloy refers to a substance composed of two or more metals or of a metal and a non-metal which have been intimately united, usually by being fused together and dissolved in each other when molten.
• aluminium alloy therefore denotes an alloy of which aluminium metal is a constituent component, which aluminium will generally comprise at least 50 wt.% - more typically at least 65 wt.% or at least 80 wt.% - of the alloy, on a metals basis.
• Metals which may be alloyed with aluminium include, but are not limited to, silicon, copper, zinc, magnesium, manganese, lithium, titanium, nickel, iron and bismuth.
• Exemplary aluminium alloys include but are not limited to Al/Mg, Al/Si, Al/Mg/Si, Al/Zn/Mg, Al/Cu/Mg and Al/Zn/Mg/Cu of which the aluminium content is at least 90 wt.% on a metals basis.
• the magnesium (Mg) content is at most 10 wt.%
• the silicon (Si) content is at most 10 wt.%
• the zinc (Zn) content is at most 5 wt.%
• the copper (Cu) content is at most 2 wt.%.
• mineral acid refers to an acid derived from one or more inorganic compounds.
• a mineral acid is not organic and all mineral acids release hydrogen ions when dissolved in water.
• phosphoric acid refers to ortho-phosphoric acid having the formula H 3 PO 4 , which acid is typically available as an aqueous solution having a concentration up to 75 wt.% H 3 PO 4 .
• phosphonic acid refers to the phosphorus oxoacid having the formula H 3 PO 3 that consists of a single pentavalent phosphorus covalently bound via single bonds to a single hydrogen and two hydroxy groups and via a double bond to an oxygen.
• hydrocarbyl group is used herein in its ordinary sense, which is well-known to those skilled in the art.
• alkylene group refers to a group that are radicals of a linear, branched or cyclic alkane, which group may be substituted or unsubstituted and may optionally be interrupted by at least one heteroatom.
• C 3 -C 6 cycloalkyl as used herein means an optionally substituted, saturated cyclic hydrocarbon having 3-6 carbon atoms.
• such cycloalkyl groups may be unsubstituted or may be substituted with one or more halogen.
• a tolerance for one or more non-halogen substituents within a cycloalkyl group will be noted in the specification.
• Exemplary cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl groups.
• a first required component of the composition of the present invention is constituted by at least one water-soluble polyphosphonic acid or a water-soluble salt thereof, wherein said polyphosphonic acid has the general formula (I): in which:
• the at least one tungstate salt is selected from the group consisting of: lithium orthotungstate (Li 2 WO 4 ); sodium orthotungstate (Na 2 WO 4 ); potassium orthotungstate (K 2 WO 4 ); ammonium orthotungstate ((NH 4 ) 2 WO 4 ); ammonium metatungstate ((NH 4 ) 6 H 2 W 12 O 40 ); potassium metatungstate (K 6 H 2 W 12 O 40 ); and, sodium metatungstate (Na 6 H 2 W 12 O 40 ).
• polar modified polypropylene waxes for example microcrystalline paraffin waxes [ CAS No. 63231-60-7 ]; montan wax and montan wax raffinates; montanic acids and salts and esters thereof; fatty acid amides such as erucamide [ CAS No. 112-84-5 ], oleamide [ CAS No. 301-02-0 ] and 1,2-ethylenebis(stearamide) [ CAS No. 110-30-5 ]; and, carnauba wax.
• any waxes included in the present composition meet at least one of the following conditions: i) an acid number of less than 200 mg KOH/g, preferably less than 100 mg KOH/g; ii) a melting point of from 40 to 200°C, preferably from 60 to 180°C; and, iii) a number average molecular weight (Mn) of at least 200 g/mol, preferably at least 400 g/mol.
• these conditions are not intended to be mutually exclusive: waxes may meet one, two or three of these conditions.
• waxes should be provided: i) in finely divided powder form, in particular in a micronized form characterized by a mean particle size of less than 20 microns, as measured by laser diffraction; and / or; ii) as an aqueous dispersion, the particles of which dispersion may desirably be characterized by a mean particle size of less than 1 micron, for instance less from 20 to 500 nm, as measured by dynamic liqht scattering.
• fluoroindates e.g. InF 4 -1
• fluorophosphates e.g. PF 6 -1
• fluoroarsenates e.g. AsF 6 -1
• fluoroantimonates e.g. SbF 6 -1
• fluorobismuthates e.g. BiF 6 -1
• fluoro sulfates e.g. SF 6 -2
• fluoroselenates e.g. SeF 6 -2
• fluorotellurates e.g.
• the conversion coating composition may optionally include up to 5 wt.%, for example from 1 to 3 wt.%, of non-ionic surfactants, based on the weight of the composition. Whilst other non-ionic surfactants may be have utility in the present invention, a particular preference for the use of fatty alcohol ethoxylates may be mentioned, of which examples include ethoxylated lauryl alcohol, stearyl alcohol, behenyl alcohol and oleyl cetyl alcohol.
• composition of the present invention may optionally comprise at least one ⁇ -hydroxycarboxylic acid represented by the general formula (III): R 1 CH(OH)COOH (III) wherein: R 1 represents a hydrogen atom, a C 1 -C 4 alkyl group, a C 2 -C 6 alkenyl group, a C 1 -C 6 alkoxy group, a C 3 -C 6 cycloalkyl group or a C 6 -C 10 aryl group.
• R 1 represents a hydrogen atom, a C 1 -C 4 alkyl group, a C 2 -C 6 alkenyl group, a C 1 -C 6 alkoxy group, a C 3 -C 6 cycloalkyl group or a C 6 -C 10 aryl group.
• Suitable ⁇ -hydroxycarboxylic acids include but are not limited to: glycolic acid; lactic acid (2-hydroxypropanoic acid); 2-hydroxybutanoic acid; 2-hydroxypentanoic acid; 2-hydroxyhexanoic acid; glucuronic acid; citric acid; mandelic acid; galacturonic acid; ribonic acid (2,3,4,5-tetrahydroxypentanoic acid); gluconic acid (2S,3S,4R,5S)-2,3,4,5,6-pentahydroxyhexanoic acid; tartronic acid; tartaric acid; and, malic acid.
• said at least one ⁇ -hydroxycarboxylic acid is selected from the group consisting of: glycolic acid; gluconic acid; lactic acid (2-hydroxypropanoic acid); 2-hydroxybutanoic acid; 2-hydroxypentanoic acid; and, 2-hydroxyhexanoic acid. More particularly, the ⁇ -hydroxycarboxylic acid(s) of the coating composition should comprise or consist of gluconic acid.
• the corrosion-protection performance of the disclosed conversion coating compositions - and resulting passivate coatings - can be enhanced by the incorporation of a transition metal salt and / or a transition metal complex therein.
• a transition metal salt and / or a transition metal complex therein are the salts or complexes of transition metals selected from the group consisting of Ce, Ni, Co, V, Fe, Zn, Zr, Mn, Mo, Zr, Hf, Bi and the lanthanides.
• the conversion coating composition may optionally further contain at least one divalent metal cation (M 2+ ) selected from the group consisting of: Mg 2+ ; Ca 2+ ; Sr 2+ and Ba 2+ .
• M 2+ divalent metal cation
• the foregoing metal ions or mixtures thereof are most conveniently introduced into the composition as metal oxides, metal hydroxides and / or soluble and compatible metal salts, including but not limited to sulfate and halide salts.
• the use of nitrate and fluoride salts for this purpose is not preferred, however.
• magnesium may be introduced into the aqueous conversion coating composition as one or more of: magnesium oxide, magnesium hydroxide; magnesium sulphate; and, magnesium chloride.
• a preference for magnesium oxide or magnesium hydroxide may be noted in this context.
• any dilution can be effected simply by the addition of water, in particular deionized and / or demineralized water, under mixing.
• the coating composition might equally be prepared within a rinse stream whereby one or more streams of the concentrate(s) is injected into a continuous stream of water.
• the conversion coating compositions may contain from 25 to 80 wt.%, preferably from 40 to 80 wt.% and more preferably from 60 to 80 wt.%, based on the weight of the composition, of water.
• the conversion coating composition may be defined by a viscosity of from 0.005 to 1 Pa.s (50 cps to 1000 cps), as measured using a Brookfield viscometer at 25°C.
• the aluminium and aluminium alloy substrate to be treated with the above described composition may be provided in various forms, including sheets, plates, cuboids, spheres, annuli, solid cylinders, tubes and wires: the provision of substrates in more complex, shaped forms - obtained by conventional techniques such as bending, blanking, casting, forging, rolling and welding - is of course not precluded.
• the aluminium or aluminium alloy to be treated may, in some embodiments, be provided as a plating or a coating on a distinct base material, of which mention may be made of iron, nickel, copper, zinc and alloys thereof: base materials comprising or consisting of steel may be noted in particular.
• any of the degreasing agent remaining on the surface should desirably be removed by rinsing the substrate surface with deionized or demineralized water.
• the surface(s) to be treated should preferably be deoxidized prior to being contacted with the acidic aqueous conversion composition.
• Such deoxidizing may include one or both of the mechanical or chemical removal of surface oxides from the surface to be coated. Desirably, at least 50%, for example a least 80% or at least 95% of the surface oxides are removed from the aluminium surface to be treated.
• the conversion coating composition is applied to the substrate.
• the conversion coating composition may be applied at ambient temperature or the temperature of the composition may be elevated prior to application to, for instance, a temperature in the range from 30°C to 90°C, for instance from 30°C to 70°C.
• an operating bath as hereinbefore described is prepared and the conversion coating composition is applied to the substrate by, without limitation, immersion, flooding, air-atomized spraying, air-assisted spraying, airless spraying, highvolume low-pressure spraying and air-assisted airless spraying.
• the minimum contact time of the composition with the substrate is most broadly that time which is sufficient to form the desired passivate film thereon: that contact time can be as little as 1 second or as great as 15 minutes in that instance where the conversion treatment is being performed on metal that will be cold worked: however, dependent upon the pH and the concentration of the applied solution, a contact time of from 5 to 300 seconds, for example from 5 to 50 seconds, would be more typical.
• the conversion coating might only be applied to that aluminium-plated surface of a steel substrate which is to form the outer side of a structure, the side which is exposed to environmental conditions: forming conversion coatings on both the inner and outer surfaces of such a plated steel material may be deleterious to the subsequent weldability of that material.
• Techniques for applying the conversion coating composition to only a singular surface include but are not limited to: painting; brushing; roll coating; wiping; air-atomized spraying; air-assisted spraying; airless spraying; highvolume low-pressure spraying; and, air-assisted airless spraying.
• the article is dried using, for instance, ambient air drying, circulating warm air, forced air drying or infrared heating.
• the surface temperature of the substrate is controlled during drying: the peak metal temperature (PMT) need not exceed 100°C and should, more particularly be in the range from 20 to 90°C, for example 50 to 75°C.
• the article be subjected to: at least one water rinse to remove residual conversion coating composition therefrom; and / or, rinsing with a dilute silicate solution.
• the rinsed substrate may be dried after completion of the rinsing step(s) or, if applicable, after each rinse solution.
• the composition according to the present invention yields a coating that is bluish in color: the depth of the blue color is determined predominantly by the base substrate and by the immersion time of that substrate in the conversion coating composition. That said, the presence of coloration is considered to be beneficial per se as it permits a visual inspection of the coating quality to be made during and after its application. Such an inspection is not possible with zirconium coatings, for instance, which are largely transparent.
• said aluminium or aluminium alloys passivated in accordance with the present invention exhibit corrosion protection for at least 200 hours before the observed onset of white rust corrosion (as defined by ASTM B-201) when treated with neutral salt spray (NSS, 5 wt.% NaCl, 95 wt.% H 2 O) under steady state conditions in accordance with the procedure of ASTM B-117.
• NSS neutral salt spray
• the present invention does not preclude supplementary conversion coatings being applied to the coating obtained in accordance with the present invention; indeed such supplementary coatings may further extend corrosion protection of the finished article.
• Inorganic coatings based on silicates and organic conversion coatings based on epoxy resins might be mentioned as non-limiting examples of supplemental conversion coatings: reference in this regard may be made to inter alia US Patent No. 5,743,971 (Inoue ) and US Patent No. 5,855,695 (McMillen ).
• These supplemental conversion coatings may be applied by any suitable means known in the art, such as by dipping, spraying, roll-coating, electro-coating or powder coating.
• Aqueous conversion coating compositions were prepared by mixing the ingredients given in Table 1 herein below: Table 1 Ingredient Inventive Composition Reference Composition 1 Reference Composition 2 (wt.% of composition) (wt.% of composition) (wt.% of composition) Water 48.0 63.0 62.5 Phosphoric acid (aq., 85% conc.) 20.0 10.0 Sulphuric acid 20.0 Codex 661 10.0 15.0 FTA 20.0 15.0 10.0 Ammonium Bifluoride 2.0 Magnesium oxide 2.5 Sodium orthotungstate 2.0

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Citations (16)

• 2023
  • 2023-01-03 EP EP23150086.9A patent/EP4397786A1/de not_active Withdrawn
  • 2023-12-05 WO PCT/EP2023/084201 patent/WO2024146725A1/en not_active Ceased

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