WO2024104977A1 - Composition aqueuse de revêtement de traitement de métal et procédé de revêtement utilisant la composition - Google Patents

Composition aqueuse de revêtement de traitement de métal et procédé de revêtement utilisant la composition Download PDF

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Publication number
WO2024104977A1
WO2024104977A1 PCT/EP2023/081646 EP2023081646W WO2024104977A1 WO 2024104977 A1 WO2024104977 A1 WO 2024104977A1 EP 2023081646 W EP2023081646 W EP 2023081646W WO 2024104977 A1 WO2024104977 A1 WO 2024104977A1
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range
coating composition
weight
coating
aqueous
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PCT/EP2023/081646
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English (en)
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Ian SEGERS
Richard Johannes Van Der Net
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Ad International B.V.
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Publication of WO2024104977A1 publication Critical patent/WO2024104977A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08—Anti-corrosive paints
    • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
    • C09D5/086—Organic or non-macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/02—Emulsion paints including aerosols
    • C09D5/024—Emulsion paints including aerosols characterised by the additives
    • 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
    • C23C22/48—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 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
    • C23C22/50—Treatment of iron or alloys based thereon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/16—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of sheets
    • H01F1/18—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of sheets with insulating coating
    • 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
    • C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
    • C23C2222/20—Use of solutions containing silanes

Definitions

  • the invention relates to an aqueous metal treatment coating composition, a coating method using the composition for treating a metal (steel) substrate.
  • Chromium-free treatment coatings for treatment of (non-grain oriented or grain oriented) electrical steel substrates, such as silicon steel, soft iron and magnetic steel in order to provide insulating properties to the coated steel substrate are known.
  • the insulation coating resulting from the steel treatment acts as an insulator between laminated steel sheets manufactured from the steel substrate in order to minimize core loss (hysteresis loss and eddy current loss).
  • ASTM Standard A976 offers a classification system C0-C6 for insulation coatings for electrical steels, mainly based on chemistry, relative insulation resistance and other functional properties.
  • chromium-free insulation coatings are water based and comprise organic (resin) components and inorganic components like phosphate(s) and pigment(s), in specific ratios depending on the intended end use,
  • E.g. EP3395923A1 discloses a chromium-free coating for insulation on electrical (Si) steel.
  • the non-oriented electrical steel sheet adhesive coating composition disclosed therein comprises a first component including an organic/inorganic composite, and a second component including a composite metal phosphate selected from certain metal phosphate monobasics, wherein the organic/inorganic composite is formed by having certain selected inorganic nanoparticles, chemically substituted with some functional groups in an organic resin, selected from specific resins.
  • the adhesive coating composition is coated on at least one surface of a non-oriented electrical steel sheet and a sheet product may be manufactured by laminating a plurality of such sheets in a stack.
  • the sheet product manufactured may be used in various applications, such as a motor, an iron core of an electric generator, an electric motor, a (small) transformer and the like.
  • Such coatings aim at providing electrical insulation between stacked coated sheets (interlayer electrical insulation), thereby preventing the occurrence of short cut between individual sheets in the stack and at reducing core losses of laminated stacks of coated electrical steels.
  • insulating properties can be enhanced by increasing the coating thickness, however weldability, heat resistance and other desired properties may be compromised.
  • a thinner coating results in a lower electrical resistance and improved weldability.
  • a higher organic resin content offers a better elasticity, deformability and lubrication during punching.
  • heat resistance of the coating having a higher organic resin content is lower, which makes the coating more susceptible to high temperatures, such as experienced during stress relief annealing (SRA).
  • SRA stress relief annealing
  • a first SRA is a heat treatment process step in which electrical steel is decarbonized and released from its internal stress and thereby experiences a reduction in the electrical core loss (hysteresis loss), resulting in specific magnetic and electrical properties which make the electrical steel suitable for application as core material in electromagnetic equipment.
  • a first SRA step is generally applied before the application of the insulation coating.
  • the sheets may stick together during the SRA or become tacky.
  • a higher inorganic (phosphate) content may improve the heat resistance and may contribute to preventing undesired sticking and tackiness.
  • inorganic phosphate coatings are apt to reduced adhesion after heat treatment (SRA) and deforming characteristics may be deteriorated.
  • CN110305574A has disclosed a one-component chromium-free non-oriented electrical steel insulating surface treatment agent having a milky white translucent appearance, which agent comprises, in wt.%, 20 - 50 waterborne polyurethane polymer, 1.0 - 10.0 film forming aid, 1.0-5.0 inorganic salt, 0.1 - 1.0 boric acid, 1.0 - 5.0 acid corrosion inhibitor, 0.5 - 5.0 magnesium hydroxide, 0.1 - 1.0 organic solvent and the balance being water.
  • Coatings comprising pigment particles like Mg(OH)2 in CN110305574A, are likely to form powder at some stages of the application process, which is undesired. Furthermore, pigment particles may reduce adhesion. Additionally, hard particles, like ceramic pigment particles have the disadvantage of wear and abrasion to the deforming equipment, like punching tools. A minor amount of organic resin is sometimes required in view of adhesion of the coating and punchability. Water dispersible resins, sometimes used in minor amounts in insulation coatings, may foam, requiring an anti-foaming agent to allow processing and application. The presence of an anti-foaming agent might also involve the risk of the development of craters and/or pinholes in the ultimate coating, which may result in enhanced corrosion sensitive spots and short cuts in the insulation.
  • the present invention aims at providing an aqueous metal treatment composition that does not suffer from at least one of the above disadvantages of an insulation and/or anti-corrosion coating based on organic resins and/or inorganic metal phosphates, or at least to a lesser extent, or to provide a suitable alternative.
  • an aqueous metal treatment coating composition that offers electrical insulation properties also after stress relief annealing, when applied to electrical steel, in combination with one or more other functional properties, such as sufficient corrosion resistance, adhesion, elasticity, heat resistance, reduced stickiness and tackiness, as well as less powder formation.
  • the invention aims at providing such a coating composition for treating a metal substrate, that can be applied as a concentrated coating composition on industrial conditions, e.g. in an inline process such as roll-to-roll, to a steel substrate.
  • Yet another object is to provide an effective corrosion resistant coating on a steel substrate for providing (temporary) protection of the steel substrate.
  • an aqueous metal treatment coating composition comprises 1 - 14 % by weight of zirconium (Zr), , based on the total weight of the aqueous coating composition, as a water soluble zirconium (Zr) component A), and 4 - 55 % by weight, of a water soluble component B) comprising at least one of a polyphosphonic acid and polyphosphonate compound, based on the total weight of the aqueous coating composition, wherein the molar ratio of the phosphonic acid groups of the water soluble component B) to zirconium (Zr) is in the range of 1 ,5 : 1 - 4 : 1 , and wherein the coating composition has a pH in the range of 2 - 9
  • the invention also relates to a method of coating a metal substrate with the above aqueous metal treatment coating composition according to the invention.
  • Such a method comprises the steps of: a) applying the aqueous metal treatment coating composition according to the invention to a metal substrate; b) drying and curing the coating on the metal substrate to which the aqueous metal treatment coating composition has been applied in step a).
  • the invention in another aspect relates to a method of preparing an aqueous metal treatment coating composition according to the invention.
  • the preparation method comprises reacting a water soluble zirconium component A) and a water soluble component B) comprising at least one of a polyphosphonic acid and polyphosphonate compound in water, adjusting the pH to a range in the range of 2-9, such that an aqueous metal treatment coating composition comprises 1 - 14 % by weight of a zirconium component A), based on the total weight of the aqueous coating composition, and comprising 4 - 55 % by weight, of a water soluble component B), based on the total weight of the aqueous coating composition, wherein the molar ratio (P : Zr) of the phosphonic acid groups of the water soluble component B) to zirconium is in the range of 1 ,5 : 1 - 4 : 1 , is obtained.
  • the invention concerns an electrical steel coated with the aqueous metal treatment coating composition of the invention.
  • the metal treatment coating composition according to the invention comprises an aqueous solution of a water soluble zirconium component A) and a water soluble component B) comprising a polyphosphonic acid and/or a polyphosphonate compound in certain amounts and in a certain ratio of phosphonic acid groups to zirconium.
  • the aqueous treatment composition has a pH in the acidic to slightly basic range.
  • An aqueous solution consisting of the above water soluble zirconium component A) and the water soluble component B) and optionally a base as neutralising agent for adjusting the pH is a clear solution, that is free from precipitates.
  • the component A) comprises zirconium (Zr) in an amount of 1-14 wt.%, based on the total weight of the aqueous coating composition.
  • the metal treatment coating composition comprises 2.5-10 wt.%, preferably 5-10 wt.% zirconium.
  • a water soluble zirconium compound for preparing the composition may be selected from e.g. hexafluoro zirconium acid and water soluble salts thereof, ammonium zirconium carbonate, potassium zirconium carbonate, zirconium acetate, zirconium ammonium citrate and zirconium tri-ethanolamine (TEA).
  • the water soluble component B) comprises a polyphosphonic acid and/or polyphosphonate compound in amount of 4-55 wt.% of the total composition. Therefore, the metal treatment coating composition advantageously comprises 10-35 wt.%, preferably 20-35 wt.% of component B).
  • component B) examples include biphosphonic acids, such as methylene diphosphonic acid (MDP), hydroxyl methylene diphosphonate (HMDP), (1-aminoethane-1 ,1-diyl) diphosphonic acid (AEDP), 1 ,4-phenylene diphosphonic acid (BDPA), biphenyl (diphosphate) (BDP), 1-hydroxy ethylidene-1 ,1-diphosphonic acid (HEDP; also known as etidronic acid), and polyphosphonates like diethylene triamine penta (methylene phosponic acid) (DETMP) or aminotris(methylenephosphonic acid) (ATMP).
  • HEDP and ATMP belong to the preferred polyphosphonic acids for component B.
  • the water soluble components A) and B) are present in concentrations allowing to achieve a dry coating weight such that the coating once dried and cured performs its electrical insulation function and/or corrosion inhibiting function.
  • a concentrated aqueous solution is desired for industrial application methods. If the concentrations of the respective components are less than the lower limits, than the desired coating weights are difficult to achieve with the most common industrial application methods. If the concentrations are above the upper limits, stability of the aqueous solution may be compromised and the viscosity increase may complicate industrial application methods.
  • the pH is in the range of 2-9. If the solution is too acidic, the solution may result in excess dissolution of iron during drying, which may be observed as a red brown colouration and/or development and/or absorption of hydrogen gas.
  • a pH above 9 may be achieved by adding suitable bases, but results in an undesired dilution of the active components A) and B), which on its turn may result in an insufficient dry coating weight to achieve its electrical insulation function and/or corrosion inhibiting function and result in difficulties in the application methods.
  • the pH is adjusted to an appropriate value representing a proper balance between reaction with the metal substrate surface, overetching and flash rust during drying, that are typical for the specific end use of the coating composition according to the invention.
  • the pH is in the range of 3-8.5.
  • the pH is in the range of 4-7, more preferably 5-6.
  • Suitable bases or neutralising agents for adjusting the pH comprise ammonia, tri-ethanolamine, tri-ethylamine, amino methyl propanol, potassium hydroxide, N,N’-dimethyl amino ethanol or basic zirconate esters (like Tyzor® TEAZ). Ammonia is a preferred base.
  • the metal treatment composition according to the invention is free from chlorides, which might affect the corrosion resistance of the coating. Therefore, advantageously the chloride content is 200 ppm or less.
  • the molar ratio of the phosphonic acid groups of the water soluble component B) to zirconium is in the range of 1.5:1 - 4:1 , preferably 2.5:1 - 3.5:1. Based on a desired industrially applicable dry coating weight the molar ratio is advantageously set within these ranges to prepare a stable aqueous treatment solution allowing to achieve the desired electrical insulation properties and corrosion inhibiting properties of the coating, in particular without formation of powder and/or dust.
  • the non-volatile content is a factor effecting the insulation, adhesion and corrosion properties.
  • the non-volatile content in the coating composition according to the invention is in the range of 5-70% by weight, such as 6-60 wt.%.
  • the non-volatile content amounts to 25-50 wt.%, more preferably 30-45 wt.%.
  • the coating composition according to the invention may comprise additives in limited amounts for special purposes such as finetuning wetting, substrate adhesion and hydrophobicity to enhance the anti-corrosion properties.
  • water soluble and water dispersible polymers and/or hydrolysed silane oligomers Up to 15 wt.% of water soluble and water dispersible polymers and/or hydrolysed silane oligomers, preferably less than 10 wt.%, such as 2 - 8 wt. %, may be present.
  • water soluble polymers comprise poly acrylic acid, poly maleic acid and co-polymers thereof.
  • Water dispersible (emulsion) polymers include poly (meth)acrylates and poly urethanes and co-polymers thereof.
  • the low content of additional water soluble and water dispersible polymers and/or hydrolysed silane oligomers is favourable in view of the SRA treatment of the coated silicon steel substrate.
  • Thickeners for increasing the viscosity of the aqueous composition in view of the type of application lubricants like waxes in view of reducing friction coefficient, improving formability including punchability, reducing powder formation during forming and punching operations, wetting agents for improving the flow characteristics and for inhibiting crater formation and an anti-foaming agent for inhibiting foam formation may be present in the composition of the invention.
  • the aqueous coating composition according to the invention may be free of particles, such as pigments..
  • the coating composition according to the invention allows to achieve sufficiently high electrical resistance, also after stress relief annealing (SRA; 2 hrs at 820 °C and at atmospheric conditions), surface resistivity (as evidenced by Franklin tests ASTM A717 >3 Q'cm 2 /laminate), sufficient elasticity and adhesion as evidenced by bending test and cross cut + tape-off test (no cracking; no peel off (Mandrell Bend Test (ISO 1519) and Cross Cut Test (ASTM D3359B))), good corrosion resistance (as appeared in an 8 hr salt spray test according to ASTM B117 with the result of ⁇ 5% red rust formation and ⁇ 5% of red rust formation after several days (168 hours) in an extended test at relative humidity RH of 99% and at a temperature of 40 °C).
  • SRA stress relief annealing
  • ASTM A717 >3 Q'cm 2 /laminate sufficient elasticity and adhesion as evidenced by bending test and cross cut + tape-off test (
  • Adhesion and coherence of the coating prepared from the composition are maintained after stress relief annealing.
  • the anti-corrosion properties of the coating composition according to the invention can also be used in (temporary) protection of steel substrates other than electrical steel.
  • the favourable anti-corrosion properties can be achieved at a small coating thickness compared to conventional anti-corrosive, waterborne coatings.
  • the small thickness and the minor amounts of organic resins/binders, if any, also result in improved weldability and less electrode contamination.
  • the coating is also not tacky, is heat resistant and does not yield allowing elevated service temperatures.
  • water based composition does not comprise organic solvents and is free from other volatile organic components allowing its use in closed coating systems where otherwise the risk of autoignition would be present due to accumulation of solvent vapours, as well as allowing its use in open systems without exposure of the operators to harmful (poisonous) solvent vapours.
  • the coating composition can be used on a variety of metal substrates including as an electrical insulating and corrosion inhibiting coating on electrical steel (Si steel), as a (temporarily) corrosion inhibiting coating on (micro)alloyed steel, metal coated steel, such as Zn (alloy) coated steel, Sn coated steel, Al(Si) coated steel, Mg and Al and their alloys coated steel and the like.
  • the way of applying the coating to the metal substrate to be coated is not limited. Suitable methods include roll coating, squeeze spray coating, electrostatic spray coating, dipping, casting, compressed air spraying and airless spraying. Roll coating is a preferred application method. Roll-to-roll (coil) coating is an example of a high productivity application process (line speed about 100 m/min). Drying and curing can be performed in a short time depending on the wet film weight, type of drying equipment, and coating composition, such as in the range of 1-100 seconds, using e.g. near IR (NIR), induction furnace or gas fired convection oven. In general the applied peak metal temperature (PMT) is dependent on the specific end properties and end use of the coated substrate.
  • NIR near IR
  • PMT applied peak metal temperature
  • the peak metal temperature is in the range of up to 320 °C or even more.
  • a PMT 216 °C or more, preferably 240 °C or more is advantageous. Drying at a relatively low temperature e.g. less than 150 °C and curing at a higher temperature (within PMT range) may be performed as two subsequent steps. Curing may occur during SRA.
  • composition solution when applied as a thin wet film on metal substrates such as (electrical) steel, has the tendency to crosslink into a network by both covalent and non- covalent interactions, initiated by increased temperatures. Full dehydration upon drying results in the formation of a water insoluble phosphonate salt of the zirconium.
  • the crosslinked film adheres to the surface metal oxides of the substrate. Typically the substrate and applied wet film are dried within a temperature range between 50 to 650 °C for 1 to 15 seconds.
  • a peak metal temperature of about 300 °C can be achieved and held at 310 °C for 60 seconds may result in a PMT of 250 °C.
  • a residence time of 7-12 seconds can be sufficient to reach a PMT of about 250 °C.
  • Preliminary drying to achieve a tack-free coating by evaporation of water can be performed in a temperature range of 80 - 120 °C .
  • the invention also relates to a method of coating a metal substrate with an aqueous metal treatment coating composition according to the invention.
  • a method of coating a metal substrate with an aqueous metal treatment coating composition according to the invention comprises the steps of: a) applying the aqueous metal treatment coating composition according to invention to a metal substrate; b) drying and curing the coating on the metal substrate to which the aqueous metal treatment coating composition has been applied in step a).
  • the aqueous metal treatment coating composition is applied as a wet film in the range of 1 - 30 g/m 2 , preferably in the range of 1 - 6 g/m 2 .
  • a wet film in the range of 1 - 30 g/m 2 , preferably in the range of 1 - 6 g/m 2 .
  • For thick wet films drying would require a relatively long time, compared to the much faster application processes, e.g. using a roll coater.
  • step b) the metal substrate to which the aqueous metal treatment coating composition has been applied in step a) is cured at a peak metal temperature (PMT) in the range of 200 - 320 °C.
  • PMT peak metal temperature
  • Favourable corrosion inhibiting properties are achieved at a PMT of at least 240 °C.
  • the coating film weight after drying is in the range of 0.2 -15 g/m 2 , preferably 0.3 - 10 g/m 2 , more preferably 0.9 - 4 g/m 2 .
  • the desired insulation and/or anti-corrosion properties are hard to achieve.
  • a dry coating weight above the upper limit offers no further substantial improvement of these properties, while other functional properties may be compromised.
  • the coating film thickness after drying and curing is in the range of 0.1 - 8 pm, preferably in the range of 0.3 - 3 pm more preferably in the range of 0.7 - 1.5 pm.
  • the coating film after drying and curing comprises Zr in the range of 60 - 3200 mg/m 2 , for example 100 -1600, such as 200 - 800, preferably 100 - 600, such as 300 - 600 mg/m 2 .
  • the dry film thickness of the insulation coating is between 0.1 and 8 pm. In this dry film thickness range, the coating forms a water resistant layer on the (NGO) electrical steel surface.
  • the insulation coating when dried and cured in the preferred temperature range, then forms a layer that is well crosslinked into a network and thereby provides a water resistant barrier onto the electrical steel surface.
  • This water resistant barrier protects the treated (NGO) electrical steel substrate against external environmental conditions. .
  • the overall dry film thickness of the insulation coating is > 0.1 pm, typically > 0.5 pm to provide a desired minimum anti-corrosion performance ( ⁇ 5% of red rust after 8 hours of NSST ASTM B117) to the (NGO) electrical steel surface.
  • the overall dry film thickness 0,25 pm or more, such as 0.50 pm or more, more preferably in the range of 0.7 - 1.5 pm to provide an anti-corrosion performance of ⁇ 5% of red rust after 24 hours of NSST (ASTM B117) to the (NGO) electrical steel surface.
  • the metal substrate is an electrical (Si) steel substrate, and preferably the coating composition according to the invention having a pH in the range of 4 - 7 is applied to the electrical (Si) steel substrate and cured at a peak metal temperature in the range of 240 - 320 °C, after application, to a dry coating weight in the range of 0.2 - 15 g/m 2 .
  • the metal substrate is an uncoated alloy steel substrate, and preferably the coating composition according to the invention having a pH in the range of 4 - 8 is dried at a peak metal temperature in the range of 80 - 550 °C and cured at a peak metal temperature in the range of 216 - 550 °C, after application, to a dry coating weight in the range of 0.2 - 4 g/m 2 , such as 0.2-2 g/m 2 .
  • the metal substrate is a tin (Sn) coated steel substrate, and preferably the coating composition according to the invention having a pH in the range of 2 - 6 is dried and cured at a peak metal temperature in the range of 216 - 320 °C, after application, to a dry coating weight in the range of 0.2 - 4 g/m 2 , such as 0.2-2 g/m 2 .
  • the metal substrate is a Zn or Zn alloy coated steel substrate, and preferably the coating composition according to the invention having a pH in the range of 3 - 6 is cured at a peak metal temperature in the range of 216 - 320 °C , after application, to a dry coating weight 0.2 - 4 g/m 2 , such as 0.2 - 2 g/m 2 .
  • a dry coating weight 0.2 - 4 g/m 2 such as 0.2 - 2 g/m 2
  • similar conditions are applied.
  • the invention relates to a method of preparing an aqueous metal treatment coating composition according to the invention.
  • the preparation method comprises reacting a water soluble zirconium component A) and a water soluble component B) comprising at least one of a polyphosphonic acid and polyphosphonate compound in water, adjusting the pH to a range in the range of 2-9, such that an aqueous metal treatment coating composition comprises 1 - 14 % by weight of the water soluble zirconium component A), based on the total weight of the aqueous coating composition, and comprises 4 - 55 % by weight, of a water soluble component B), based on the total weight of the aqueous coating composition, wherein the molar ratio of the phosphonic acid groups of the water soluble component B) to zirconium is in the range of 1 ,5 : 1 - 4 : 1 , is obtained.
  • the invention relates to an electrical steel substrate having an insulation coating, wherein the insulation coating comprises zirconium in the range of 60 - 3200 mg/m 2 , for example 100 -1600, such as 200 - 800, preferably 100 - 600, such as 300 - 600 mg/m 2 , and at least one of a polyphosphonic acid and polyphosphonate compound, wherein the molar ratio of the phosphonic acid groups to zirconium (Zr) is in the range of 1 ,5 : 1 - 4 : 1 , preferably obtained from the aqueous coating composition according to any one of claims 1 - 11 , and has a film thickness after drying and curing in the range of 0.1 - 8 pm, preferably in the range of 0.3 - 3 pm, more preferably in the range of 0.7 - 1 .5 pm.
  • the insulation coating comprises zirconium in the range of 60 - 3200 mg/m 2 , for example 100 -1600, such as 200 - 800, preferably 100 - 600,
  • Coating compositions Inventive Examples 1-8 and 10- 38 were prepared from starting materials, that are listed in the below Tables 3-6.
  • a solution of the zirconium compound (component A)) in the indicated amount in water was provided and stirred using a magnetic stirrer. While stirring, component B) in the indicated amount was slowly added to the aqueous solution of the zirconium compound. After completion of the reaction (typically 6-8) hrs any weight loss is compensated by make-up water.
  • the pH is adjusted by adding a base/neutralising agent.
  • the initial aqueous coating composition consisting of the water-soluble zirconium compounds and component B) and optionally a base as neutralising agent is stable over time, remains a clear transparent solution and no noticeable change of viscosity is observed.
  • the comparative examples were prepared in a similar way.
  • Initial stability is defined as maintaining a stable liquid product from the moment of mixing the components up to at least one day (24 hrs).
  • Long term stability is defined as maintaining a stable liquid product from the moment of mixing the components up to at least two weeks.
  • the liquid composition is visually evaluated. The results were qualitatively determined.
  • a transparent or a non-transparent homogeneous solution (of which the viscosity does not change significantly over time (applicable to long term stability)) was qualified as a stable liquid composition.
  • a non-transparent liquid composition e.g. containing heterogeneously distributed precipitates and/or containing sedimented precipitates), a phase separated liquid composition and a gelled transparent and/or non-transparent composition are qualified as a non-stable liquid composition.
  • Dry film condition The condition of the dry film, when applied in the desired dry film thickness (DFT) and dried at the desired peak metal temperature (PMT), on steel substrate (both cold rolled steel (CRS) and electrical steel (ES)). Both cold rolled steel and electrical steel were cleaned with a mild alkaline cleaner (pH » 9), rinsed with demi water and dried with compressed air prior to the application of the liquid sample of the Inventive Examples and Comparative Examples.
  • the wet liquid sample as is, was applied on the cleaned steel surface using a wire coating bar, whereafter the applied wet film was dried and cured using hot air produced by a convection oven.
  • the peak metal temperature of the steel substrate was at least 240 °C during the curing process.
  • the amount of wet liquid sample, that was applied in order to obtain the desired DFT, is within the range of 6 ⁇ 1 g/m 2 .
  • the obtained coating film was visually observed. The results were qualitatively determined.
  • the desired condition is a transparent, stable dry film.
  • Anti-corrosion properties The anti-corrosion properties of the dry film, as applied on electrical steel substrate by the procedures described above in the "Dry film condition" section, were examined in 8 hours of Neutral Salt Spray Test (NSST: ASTM B117).
  • the results represent the percentage of exposed surface that obtained red rust after 8 hours of exposure.
  • Resistivity The resistivity properties (Q-cm 2 /laminate) of the dry film on electrical steel substrate, before and after Stress Relief Annealing (SRA: 2 hours at 820 °C in ambient conditions), as measured by a Franklin tester (ASTM A717), were studied.
  • SRA Stress Relief Annealing
  • ASTM A717 The dry film was applied by the procedures as stated in the "Dry film condition" section.
  • Coating condition after SRA The condition of the dry film on pre-annealed/decarbonized electrical steel, as applied according to the procedure as stated in the "Dry film condition" section, after a Stress Relief Annealing treatment (SRA: 2 hours at 820 °C in ambient conditions) was visually examined. The adhesion of this SRA treated dry film on the pre- annealed/decarbonized electrical steel after bending the substrate and tape-off a crosshatch was visually evaluated. The obtained coating film was visually observed. The results were qualitatively determined.
  • the coating is qualified as an adherent coating if no detachment from the underlying substrate, no powdering, flaking and decomposition of the coating itself, as well as no burns of the coating itself is observed after the SRA treatment and during the bend test and/or crosshatch + tape-off test.
  • Table 7 presents the test result regarding stability, dry film condition and anti-corrosion properties.
  • Table 8 summarizes tests results regarding resistivity and coating condition after SRA for Inventive Examples 2, 26 30, 35 and Comparative Example 2 respectively.
  • Inventive Examples 1-7 show the effect of increasing the solution pH of the composition at a constant Zrphosphonic acid groups ratio of 1:3,2 using a neutralisation agent (ammonia) on the long term stability of this composition, as well as at ratios of 1:4 and 1 :2 respectively.
  • Inventive Examples 11-15 show the possibility of changing the neutralisation agent and its effect on the initial stability and/or long term stability, as well as the dry film condition on cold rolled steel (CRS) and electrical steel substrate (ES) and the anti-corrosion properties of the dry film on electrical steel substrate (ES).
  • Inventive Examples 8 and 10 show the effect of either changing the Zr-component source or the polyphosphonate component on the stability, dry film condition on cold rolled steel and electrical steel substrate and anti-corrosion properties on electrical steel substrate.
  • Inventive Examples 21-28 show the relation between varying the ratio of Zr to phosphonic acid groups in preparing an aqueous metal treatment composition consisting of a Zr component, diphosphonic acid and an optional polymer and the initial and/or long term stability.
  • this ratio on the dry film condition on cold rolled steel and an electrical steel substrate and the resulting anti-corrosion properties of this dry film on electrical steel substrate were examined.
  • Inventive Examples 29-34 also show the effect of increasing the solution pH of the composition at a Zr: phosphonic acid group ratio of 1 :3,2 using a neutralisation agent (ammonia) on the long term stability of a composition consisting of a Zr component, diphosphonic acid and an optional polymer.
  • a neutralisation agent ammonia
  • Comparative Examples show the effects of changing the Zr-component source and/or the polyphosphonate component to another (monophosphonate) chelating component and/or using a Zr-component or chelate component on its own, on dry film conditions on cold rolled steel substrate and electrical steel substrate, anti-corrosion properties of the dry film and/or conditions of the dry film on electrical steel after SRA treatment.
  • Comparative Examples 6 and 7 show the effect on the initial and/or long term liquid composition stability, on the dry film condition and on the anti-corrosion properties of this dry film on cold rolled steel and electrical steel substrate when setting the molar ratio of the Zr compound to the phosphonic acid groups of component B) in preparing an aqueous metal treatment composition consisting of a Zr component, diphosphonic acid and an optional polymer, outside the phosphonic acid group : Zr ratio range of 1.5: 1 - 4:1.
  • Inventive Examples 2, 36, 37 and 38 and Comparative Example 8 show the effect of increasing the optional polymer content at the expense of the zirconium compound and component B) in the aqueous metal treatment composition on the anti-corrosive properties of the transparent stable dry film on an electrical steel substrate.
  • Comparative Example 9 shows the effect on the dry film condition and anti-corrosion property of the dry film, when an alternative optional polymer (J) is used in an amount above 15 wt.%.

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Abstract

Une composition aqueuse de revêtement de traitement de métal comprend de 1 à 14 % en poids d'un zirconium, sur la base du poids total de la composition aqueuse de revêtement, en tant que composant de zirconium hydrosoluble A), et de 4 à 55 % en poids d'un composant hydrosoluble B) comprenant au moins l'un d'un acide polyphosphonique et d'un composé polyphosphonate, tel que l'acide étidronique, sur la base du poids total de la composition aqueuse de revêtement, le rapport molaire des groupes d'acide phosphonique du composant hydrosoluble B) au zirconium (Zr) étant dans la plage de 1,5:1 à 4:1, et la composition de revêtement ayant un pH dans la plage de 2 à 9. Un revêtement obtenu à partir de la composition de revêtement sur un substrat en acier possède des propriétés d'isolation électrique et/ou d'inhibition de la corrosion.
PCT/EP2023/081646 2022-11-18 2023-11-13 Composition aqueuse de revêtement de traitement de métal et procédé de revêtement utilisant la composition WO2024104977A1 (fr)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0096526A2 (fr) * 1982-06-01 1983-12-21 INTERNATIONAL PAINT Public Limited Company Peinture anti-corrosive
WO1998024164A1 (fr) * 1996-11-29 1998-06-04 Herberts Austria Gmbh Agent de recouvrement pour la production d'un revetement electro-isolant sur une tole d'acier electrique
JP2007162098A (ja) * 2005-12-15 2007-06-28 Nippon Parkerizing Co Ltd 水系金属表面処理剤、表面処理方法及び表面処理金属材料
WO2008012248A1 (fr) * 2006-07-25 2008-01-31 Basf Se Procédé de passivation de surfaces métalliques avec des copolymères comportant des groupements acide phosphorique et/ou acide phosphonique
WO2015114068A1 (fr) * 2014-01-30 2015-08-06 Thyssenkrupp Electrical Steel Gmbh Produit plat en acier électrique à grains orientés comprenant un revêtement d'isolation
EP3395923A1 (fr) 2015-12-21 2018-10-31 Posco Composition de revêtement adhésive de feuille d'acier électrique non orientée, produit feuille d'acier électrique non orientée, et son procédé de fabrication
CN110305574A (zh) 2019-07-02 2019-10-08 上海优梓新材料科技有限公司 一种单组份无铬环保无取向电工钢绝缘表面处理剂

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0096526A2 (fr) * 1982-06-01 1983-12-21 INTERNATIONAL PAINT Public Limited Company Peinture anti-corrosive
WO1998024164A1 (fr) * 1996-11-29 1998-06-04 Herberts Austria Gmbh Agent de recouvrement pour la production d'un revetement electro-isolant sur une tole d'acier electrique
JP2007162098A (ja) * 2005-12-15 2007-06-28 Nippon Parkerizing Co Ltd 水系金属表面処理剤、表面処理方法及び表面処理金属材料
WO2008012248A1 (fr) * 2006-07-25 2008-01-31 Basf Se Procédé de passivation de surfaces métalliques avec des copolymères comportant des groupements acide phosphorique et/ou acide phosphonique
WO2015114068A1 (fr) * 2014-01-30 2015-08-06 Thyssenkrupp Electrical Steel Gmbh Produit plat en acier électrique à grains orientés comprenant un revêtement d'isolation
EP3395923A1 (fr) 2015-12-21 2018-10-31 Posco Composition de revêtement adhésive de feuille d'acier électrique non orientée, produit feuille d'acier électrique non orientée, et son procédé de fabrication
CN110305574A (zh) 2019-07-02 2019-10-08 上海优梓新材料科技有限公司 一种单组份无铬环保无取向电工钢绝缘表面处理剂

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