JP6622206B2 - Method for coating metal surface, substrate coated by said method and use thereof - Google Patents

Description

  The present invention provides a method for coating metal surfaces, optionally with colored conversion layers, in particular alternatives to alkali metal phosphate coating treatments, such as iron phosphate coating treatments, and correspondingly coated metal surfaces. And a use of the coated substrate.

  A method for producing an alkali metal phosphate film as a pretreatment layer, particularly before coating, is frequently found. Typically, fresh new alkali metal phosphate solutions are substantially free of aluminum, iron and zinc, or contain very little of them. The acidic alkali metal phosphate aqueous solution contains phosphate ions in addition to at least one alkali metal and / or ammonium ion, and is eluted from the metal surface due to the pickling effect of the solution on the metal surface. Contains ions of alloying components of metals such as aluminum, iron or / and zinc, and small amounts of pickled metal materials. In the alkali metal phosphate film treatment, the phase mainly formed in the alkali metal phosphate layer is the corresponding phosphate, oxide or / and hydroxide of the metal from the surface of the substrate to be treated. is there.

  An alkali metal phosphate solution or an alkali metal phosphate film is also called an iron phosphate solution or an iron phosphate film when used with iron and steel materials. Alkali metal phosphate coatings are also commonly referred to as so-called “non-layer forming phosphate coating treatments” according to Werner Rausch: Die Phosphatierung von Metallen, Saulgau 1988 (especially see pages 109 to 118). . This name is misleading because it also forms a distinctly thinner layer than other phosphate layers, such as various zinc phosphate coatings. Alkali metal phosphate solutions always contain a high content of at least one alkali metal, such as sodium or / and ammonium.

  Alkali metal phosphate coating treatment can often be carried out easily and economically. However, high-quality alkali metal phosphate coatings only provide limited corrosion protection, despite the addition of a second chemical conversion treatment, usually a) made of cold-rolled steel A powder coating based on an epoxy polyester powder coating with a thickness of 60 μm to 80 μm on a plate, tested over 500 hours by the salt spray test NSS according to DIN 50021, with an unwinding of 3 mm Corrosion protection with inferior or more than 3 mm penetration, or usually b) wet coating based on polyurethane isocyanate paint with a thickness of 60 μm to 80 μm on a cold rolled steel plate, to DIN 50021 Penetration is inferior to 4 mm, i.e. penetration is 4 mm, tested over 500 hours according to compliant salt spray test NSS Corrosion protection above and usually c) powder coating based on epoxy polyester powder coating with a thickness of 60 μm to 80 μm on cold rolled steel plate, according to DIN EN ISO 2409 It is inferior to GT3 in the cross-cut test in the 240-hour test by the KK test to which it conforms, that is, it shows only a coating adhesion of GT3 or higher.

  Therefore, in general, in the alkali metal phosphate film treatment, it is necessary to provide a second chemical conversion layer to be further applied and, in many cases, at least one subsequently applied coating layer. Such multi-stage processes are not only expensive, but also require the addition of multiple baths or / and treatment zones, and optionally additional rinsing or / and drying steps, and are expensive and time consuming. Since the adhesion of alkali metal phosphate films is often inadequate, an additional conversion film treatment, for example based on zirconium hexafluoride or / and silane, must be performed before painting. . This coating method is therefore particularly labor intensive and expensive. The high phosphate content of the alkali metal phosphate film treatment is also a drawback. This is because phosphate needs to be costly for wastewater treatment.

  Alkali metal phosphate coating treatment is often applied in multiple stages. In the first stage, only cleaning is performed preferentially, and layer formation is performed in the second stage. This is followed by a rinsing or a nachspelen.

  Find an aqueous composition that can be easily applied, has an environmentally friendly composition as much as possible, and provides higher corrosion protection than a high quality alkali metal phosphate coating That was a challenge.

The above problem is solved by a method of coating a metal surface with an acidic aqueous chemical composition which is a solution or dispersion, the composition comprising:
TiF ₆ ²⁺ , ZrF ₆ ^{2+ in} the form of ions calculated as ZrF ₆ ²⁺ and / or HfF ₆ ²⁺ total from 0.01 g / L to 1 g / L,
Fe ²⁺ ion, Mn ion or / and Zn ion, respectively 0 g / L or 0.01 g / L to 1 g / L, at least one of these ions having a content of 0.01 g / L to 1 g / L Included in the range of,
Here, it is preferable that Mn ions or / and Zn ions are included,
Organic polymer or / and copolymer stable at a pH of less than 6.5 From 0 g / L or 0.01 g / L to 2 g / L based on solids content,
From 0 g / L or 0.01 g / L to 2 g / L based on the particulate SiO ₂ solid content with an average particle size measured by a scanning electron microscope of less than 0.3 μm,
At least one surfactant from about 0 g / L or from 0.01 g / L to 10 g / L;
Even if CO ₃ ²⁺ or SO ₄ ²⁺ is present, an anion selected from the group consisting of carbonate ion, nitrate ion and sulfate ion converted to NO ₃ ⁺ is about 0 g / L or 0.05 g / From L to 10g / L,
Carboxylic acid anions or / and sulfonic acid anions calculated as the corresponding anions that do not inhibit or hardly inhibit layer formation from 0 g / L or 0.001 g / L to 2 g / L,
Here, the content of molybdate ion calculated as MoO ₄ ²⁺ and / or the content of P-containing oxyanion calculated as PO ₄ ³⁺ is less than 0.1 g / L or about 0 g / L, respectively. And where the acidic aqueous composition has a pH value in the range of 2.5 to 6.5, preferably in the range of 3.0 to 5.5.

TiF ₆ ²⁺ , ZrF ₆ ²⁺ or / and HfF ₆ ²⁺ ions are nearly equivalent and exchangeable in the acidic aqueous chemical composition, but ZrF ₆ ²⁺ ions are produced by the method described above. Often results in the best properties of the resulting conversion coating. Preferably, the content of TiF ₆ ²⁺ , ZrF ₆ ²⁺ or / and HfF ₆ ^{2+ in} the acidic aqueous chemical composition is from 0.05 g / L to less than 1 g / L, from 0.1 g / L From 0.8 g / L, from 0.15 g / L to 0.50 g / L, or from 0.20 g / L to 0.33 g / L.

Here, in the cation content of only Fe ²⁺ ions in the acidic aqueous chemical composition based on the total content of Fe ²⁺ ions, Mn ions and Zn ions, this content is at least partially intended. It is preferably derived from what is added automatically. Both manganese and zinc ions, as well as a limited range of Fe ^2+, are almost equivalent in an acidic aqueous chemical composition and are interchangeable, but manganese or / and zinc ions are Often results in the best properties of the conversion coating produced by the process. When manganese and zinc are added to an acidic aqueous chemical composition, it is particularly preferred that the manganese content be greater than the zinc content. The acidic aqueous chemical composition contains Fe ²⁺ ions from 0 g / L or from 0.01 g / L to 0.3 g / L, or from 0.02 g / L to 0.15 g / L, and Mn ions to 0.1%. It is preferable to contain from 01 g / L to 1 g / L, or / and Zn ions from 0.01 g / L to 1 g / L, or from 0.1 g / L to 0.6 g / L. Acidic aqueous chemical compositions may have Mn ions from 0.1 g / L to 0.6 g / L, or 0.2 g / L to 0.4 g / L, and / or Zn ions from 0.1 g / L. It is particularly preferred to contain up to 0.6 g / L or from 0.2 g / L to 0.4 g / L.

Preference is given to carrying out substantially free of phosphate ions (PO ₄ <0.1 g / L) or completely free of phosphate ions (PO ₄ approximately 0 g / L or exactly 0 g / L). In a separate alternative, the phosphorus content calculated as PO ₄ ³⁺ from 0.001 g / L to less than 0.1 g / L is in particular brought in from the outside (Einschlungpungen) and impurities Therefore, it cannot be excluded. Furthermore, it is substantially free of phosphate ions (P _x O _y less than 0.1 g / L) or completely free of phosphate ions (P _x O _{y of} about 0 g / L or exactly 0 g / L). It is preferable to implement.

  The addition of an organic polymer or / and an organic copolymer can contribute to further improving the properties of the conversion coating produced by the present method and optionally omitting additional coating. The content of the organic polymer or / and organic copolymer in the acidic aqueous chemical composition is from 0.01 g / L to 3 g / L, from 0.1 g / L to 2.5 g / L, from 0.2 g / L. Preferably it is up to 2 g / L, from 0.4 g / L to 1.5 g / L, or from 0.6 g / L to 1.2 g / L. The organic polymer or / and organic copolymer is preferably based on (meth) acrylate / (meth) acrylic acid or / and vinyl acetate acrylic copolymer.

  If coating is omitted, the produced coating is a passivation layer, and in the case of corrosion protection, it may be blank corrosion protection.

The addition of finely particulate SiO ₂ (especially less than 0.3 μm), eg SiO ₂ nanoparticles, can show a positive effect similar to the addition of organic polymers or / and organic copolymers, for example. The difference is often that in the case of SiO ₂ the layer formation and thus the coating is more uniform.

  In principle, at least one nonionic, anionic, cationic or / and zwitterionic surfactant, respectively, may be added. Here, the addition of at least one nonionic surfactant is particularly preferred.

  The addition of an anion selected from the group consisting of carbonate ion, nitrate ion and sulfate ion is often performed by addition of a cation with a water-soluble salt. Here, nitrate ions are particularly preferred.

  In order to avoid or reduce the anions of inorganic acids, it is basically possible to add carboxylate anions, for example by acetic acid or / and manganese carboxylates, as substitutes or supplements for these anions. Often preferred. Basically, it is water-soluble, stable in the pH range, does not have a complex material composition, forms anions in water, and does not inhibit layer formation depending on the type and amount of anions. Any and all kinds of carboxylic acids and their derivatives, such as salts or esters, can be added, provided that they optionally complex alkali metal ions and / or alkaline earth metal ions that are not involved in layer formation. This is in particular aliphatic carboxylic acids, and monocarboxylic acids, dicarboxylic acids or / and polycarboxylic acids, such as hydroxycarboxylic acids. It should be noted that when a carboxylate anion is added, this does not inhibit layer formation. This is because, for example, citrate ions and individual separate complexing agents can sometimes inhibit layer formation depending on the type and amount of anions.

  Here, the addition of at least one sulphonic acid, such as methanesulphonic acid, amidosulphonic acid or / and derivatives thereof, may be advantageous to act as a promoter or / and as another counter ion.

Basically, the content of molybdate ions calculated as MoO ₄ ranges from 0 g / L or from 0.01 g / L to less than 0.5 g / L, in particular from 0.02 g / L to 0.3 g / L. It is preferable that the range is from 0.01 g / L to less than 0.1 g / L. The addition of molybdate ions is effective only when the addition amount is very small.

  The addition of P-containing oxyanions, such as orthophosphate ions, concentrated phosphate ions and phosphonate ions, in particular due to possible wastewater loads, and possibly due to the formation of relatively large amounts of sludge, Processing should be avoided as it can be expensive. Particularly in the case of P-containing oxyanions, it is preferable that the content of P-containing oxyanions is not added, and preferably the content of P-containing oxyanions is brought in as much as possible for reasons of environmental compatibility and avoiding treatment costs. It should also be noted that there is no.

In the process according to the invention, the acidic aqueous composition optionally further comprises, consists essentially of, or preferably consists of:
Total of lithium, sodium or / and potassium ions from 0.03 g / L to 5 g / L,
Ammonium ion from 0 g / L or 0.05 g / L to 5 g / L,
Total of Co ions or / and Ni ions from about 0 g / L or 0.05 g / L to 0.3 g / L,
Chlorate ion calculated as ClO ₃ ⁻ , nitrite ion calculated as NO ₂ and / or peroxide ion calculated as H ₂ O ₂ , respectively, from 0 g / L or 0.01 g / L to 0.8 g / L Up to L,
Free fluoride ion calculated as F ⁻ from 0 g / L or 0.01 g / L to 0.5 g / L, and vanadate ion calculated as VO ₄ ³⁻ from 0 g / L or 0.01 g / L to 0 Up to 2 g / L.

  Basically, the content of lithium, sodium, potassium or / and ammonium is usually avoided in order to achieve charge balance and not to add only multivalent cations, such as heavy metal ions. I can't. The monovalent cation is particularly preferably a sodium ion. Monovalent cations can be used approximately equivalently and interchangeably in acidic aqueous chemical compositions and are often necessary for pH adjustment.

  Again, as in many coating methods, even if cobalt or / and nickel is a problem with respect to environmental compatibility and occupational health, the addition of these elements is advantageous because it achieves better corrosion protection.

The addition of at least one accelerator, in particular chlorate ions, nitrite ions or / and peroxide ions, is sometimes beneficial. However, it should be noted here that the amount is suitable, for example the content of NO ₂ is clearly less than 1 g / L. The addition of at least one accelerator can promote layer formation and improve the properties of the film produced by the method. Here, excessive metering of the accelerator should also be avoided in order not to disturb the layer formation as in Example B40. The addition of nitroguanidine has proved ineffective.

The content of one or more complex fluorides alone often results in too little content of free fluoride ions. The content or / and addition of at least one fluoride can increase the content of free fluoride ions only slightly. The content of free fluoride ions, particularly suitable for substrate surfaces containing aluminum, is often in the range from 0.01 g / L to 0.5 g / L, calculated as F ⁻ .

  Addition of at least one vanadium compound can also clearly enhance corrosion protection.

Here, other elemental contents of the substrate and the metal surface of the equipment, in particular Fe ²⁺ ions and alloying elements or their ions, reach the bath by the pickling action of the acidic aqueous chemical composition, and in some cases It is not impossible to accumulate in the bath composition.

  On the other hand, in the case of current coating methods and equipment, the content of ions and substances from other equipment areas, e.g. cleaning processes adopted before it, is notwithstanding the possibility of rinsing with water. It is not impossible to bring in small quantities. Thereby, in particular the content of alkali metals, ammonium, complexing agents, surfactants, anionic impurities or / and other impurities or their ions in the washing bath can be brought into the bath composition according to the invention. is there. However, since a separate preceding cleaning step is not necessarily provided, introduction of foreign ions can be eliminated as much as possible by the chemical treatment liquid. In the most economical case, the washing step can be carried out using water containing a surfactant and without the content of Reinergergeest (Bilder).

  Since the cleaning can be carried out on the one hand before the conversion coating treatment, the substrate is cleaned, in particular with an alkali, before it is brought into contact with the aqueous composition. On the other hand, since the aqueous composition may contain at least one surfactant, cleaning and chemical conversion film treatment are performed in the same method step in addition to or instead of this cleaning step.

  Preferably, the aqueous chemical composition is a carboxylic acid, phosphate, phosphonate, or / and calcium, chromium, chromate, cobalt, copper, magnesium, molybdenum, nickel, vanadium or / and tin or / and silane The / silanol / siloxane / polysiloxane compound or / and the ionic content are intentionally not added at all, or only a small content, eg up to 0.1 g / L each, is intentionally added. Silane / silanol / siloxane / polysiloxane means silane, silanol, siloxane or / and polysiloxane, in water and in film treatment, eg starting from silane, silanol or / and very quickly Siloxanes can occur, and sometimes they can also result in polysiloxanes (depending on chemical definition).

  The content of alkaline earth metals, such as calcium or / and magnesium, in the acidic aqueous chemical composition is more than 0.2 g / L in total to avoid precipitation in the presence of fluoride as much as possible. Preferably not much.

The following variants are particularly preferred:
The acidic aqueous chemical composition has a pH value in the range of 2.5 to 6.5 and includes, consists essentially of, or generally consists of:

For variant A:
TiF ₆ ^2+, from ZrF ₆ ²⁺ or / and HfF ₆ ²⁺ 0.01 g / L in the form of ions is calculated as ZrF ₆ ²⁺ to 1 g / L, and Fe ²⁺ ions, Mn ions or / and Zn ions from 0 g / L or from 0.01 g / L to 1 g / L respectively, at least one of those ions is included in a content range from 0.01 g / L to 1 g / L,
And optionally from 0.01 g / L to 2 g / L based on the particulate SiO ₂ solid content with an average particle size of less than 0.3 μm,
Optionally at least one surfactant from 0.01 g / L to 10 g / L, and phosphate ion content PO ₄ less than 0.1 g / L.

For variant B:
TiF ₆ ²⁺ , ZrF ₆ ^{2+ in} the form of ions calculated as ZrF ₆ ²⁺ and / or HfF ₆ ^{2+ from} 0.01 g / L to 1 g / L,
Fe ²⁺ ions, Mn ions and / or Zn ions, each having a content of 0 g / L or 0.01 g / L to 1 g / L, at least one of these ions having a content of 0.01 g / L to 1 g / L An organic polymer or / and copolymer that is included in the range and stable at a pH value of less than 6.5, from 0.01 g / L to 2 g / L,
And optionally from 0.01 g / L to 2 g / L based on the particulate SiO ₂ solid content with an average particle size of less than 0.3 μm,
As well as optionally at least one surfactant from 0.01 g / L to 10 g / L,
In some cases, even if CO ₃ ²⁺ or SO ₄ ²⁺ is present, an anion selected from the group consisting of carbonate ion, nitrate ion and sulfate ion in terms of NO ₃ ⁺ 0.05 g / From L to 10g / L,
And optionally calculated as the corresponding anion, carboxylate anions and / or sulfonate anions which do not inhibit or hardly inhibit layer formation from 0.001 g / L to 2 g / L,
Here, the content of molybdate ions calculated as MoO ₄ ²⁺ or / and the content of P-containing oxyanions calculated as PO ₄ ³⁺ are less than 0.1 g / L or about 0 g / L, respectively. is there.

For variant C:
TiF ₆ ^2+, in the form of ions is calculated as ZrF ₆ ²⁺ ZrF ₆ ²⁺ or / and HfF ₆ ²⁺ 0.01 g / L or 1 g / L
Fe ²⁺ ions, Mn ions and / or Zn ions, each containing from 0 g / L or 0.01 g / L to 1 g / L, at least one of these ions containing from 0.01 g / L to 1 g / L The content of molybdate ions included as a range of MoO ₄ ²⁺ from 0.01 g / L to less than 0.5 g / L,
And optionally an organic polymer or / and copolymer stable at a pH value of less than 6.5, from 0.01 g / L to 2 g / L,
And optionally from 0.01 g / L to 2 g / L based on the particulate SiO ₂ solid content with an average particle size of less than 0.3 μm,
As well as optionally at least one surfactant from 0.01 g / L to 10 g / L,
In some cases, even if CO ₃ ²⁺ or SO ₄ ²⁺ is present, an anion selected from the group consisting of carbonate ion, nitrate ion and sulfate ion in terms of NO ₃ ⁺ 0.05 g / L From 10 to 10 g / L, and optionally calculated as the corresponding anion, carboxylate anions and / or sulfonate anions that do not inhibit or hardly inhibit layer formation from 0.001 g / L to 2 g / L,
Here, the content of molybdate ions calculated as MoO ₄ ²⁺ is in the range from 0.01 g / L to less than 0.5 g / L, and the P-containing oxyanion calculated as PO ₄ ³⁺ The content is less than 0.1 g / L or about 0 g / L.

In all three variants, Mn ions and / or Zn ions are added, while the content of Fe ²⁺ ions is pickled from the iron-rich metal substrate only by the pickling effect of the acid conversion composition. It is preferable. Optionally, the coating is then applied at least once.

Particularly preferably, the acidic aqueous chemical composition that is a solution or dispersion comprises, consists essentially of, or consists of:
TiF ₆ ^2+, ZrF the form of ions is calculated as ZrF ₆ ^{2 +} ₆ ^{2 +} or / and HfF ₆ Mn ions ²⁺ from the total 0.01 g / L to 1 g / L or / and Zn ions 0 g / L or From 0.01 g / L to 1 g / L, at least one of these ions is included in a content range from 0.01 g / L to 1 g / L.
Fe ²⁺ ions from 0 g / L or from 0.01 g / L to 0.3 g / L,
Here, preferably Mn ions or / and Zn ions are included,
Organic polymer or / and copolymer stable at a pH value of less than 6.5 From 0 g / L or from 0.01 g / L to 1 g / L based on solids content,
From 0 g / L or 0.01 g / L to 1 g / L on the basis of the content of particulate SiO ₂ solid having an average particle size of less than 0.3 μm as measured with a scanning electron microscope,
At least one surfactant From about 0 g / L or from 0.01 g / to 6 g / L Even if CO ₃ ²⁺ or SO ₄ ²⁺ is present, it is converted into NO ₃ ⁺ and converted into carbonate ions and nitrate ions. And anions selected from the group consisting of sulfate ions from about 0 g / L or 0.05 g / L to 6 g / L, and carboxylate anions that do not inhibit or hardly inhibit layer formation, calculated as the corresponding anions Or / and sulfonate anion 0 g / L or 0.001 g / L to 1 g / L,
Here, the content of molybdate ion calculated as MoO ₄ ²⁺ and / or the content of P-containing oxyanion calculated as PO ₄ ³⁺ is less than 0.1 g / L or about 0 g / L, respectively. And wherein the aqueous composition has a pH value in the range of 2.5 to 6.5, preferably in the range of 3.0 to 5.5.

It is particularly preferred that the acidic aqueous composition comprises, consists essentially of, or further comprises:
Total of lithium, sodium or / and potassium ions from 0.1 g / L to 5 g / L,
Ammonium ion from 0 g / L or 0.05 g / L to 5 g / L,
Total of Co ions or / and Ni ions from about 0 g / L or 0.05 g / L to 0.2 g / L,
Chlorate ion calculated as ClO ₃ ⁻ , nitrate ion calculated as NO ₂ , and / or peroxide ion calculated as H ₂ O ₂ , about 0 g / L or 0.01 g / L to 0.4 g, respectively. Up to / L,
Free fluoride ion calculated as F ⁻ from 0 g / L or 0.01 g / L to 0.5 g / L, and vanadate ion calculated as VO ₄ ³⁻ from 0 g / L or 0.01 g / L to 0 Up to 1 g / L.

  Here, the bath composition according to the invention can preferably be prepared by diluting one or two concentrates and water with a dilution factor ranging from 5: 1 to 40: 1. The second concentrate contains, for example, at least one surfactant and may also be aqueous. Here, the fluoride may be added as monofluoride, as difluoride or / and in the form of the corresponding acid. The content of free fluoride is often in the range from 0.01 g / L to 0.2 g / L.

  In the case of an acidic aqueous chemical composition, it has a conductivity of, for example, about 200 μS / cm to 600 μS / cm, whether it is started, replenished with a liquid water level in the bath, or first rinsed after the conversion coating treatment. It is preferred to work with tap water or completely demineralized water.

  After this initial rinsing step, VE rinsing with fully demineralized water (VE) is typically only necessary as the last rinse to prevent drying of salinity (Salzfracht), which can provide relatively poor corrosion protection. .

  Hot dip galvanized steel (HDG) has poorer coating adhesion and corrosion protection than cold rolled steel (CRS) steel. If the zinc content in the acidic aqueous conversion composition is reduced or completely avoided, the properties of the coating on the galvanized sheet are often improved.

Although the content of Fe ²⁺ ions does not significantly degrade the properties of the film, it has been found that Fe ²⁺ ions are gradually oxidized to Fe ³⁺ and precipitate as bath sludge. . Therefore, it is preferable that the acidic aqueous chemical composition has a content of manganese ions and / or zinc ions.

  An aqueous composition containing a surfactant can further improve the cleaning after degreasing or / and pickling, or at least facilitate the omission of degreasing before the conversion coating treatment, so that a one-pot cleaning is possible. As a result, the cleaning step is omitted and performed in the range of the chemical conversion film treatment.

  In the method according to the invention, in the treatment of the part, at least one substrate having a metal surface can be contacted with the aqueous composition for a time ranging from 1 second to 10 minutes, in particular from 0.5 minutes to 10 minutes. preferable. Here, particularly preferably, in the case of immersion, the contact is made for a time in the range from 1 minute to 10 minutes, or in the case of spraying, the contact is made for a time in the range from 0.5 minutes to 6 minutes. Therefore, in the case of this composition, for example, the same treatment time as in the case of alkali metal phosphate film treatment may be used, and thereby, from the alkali metal phosphate film treatment of equipment to the chemical film treatment according to the present invention. Can be easily switched. This is because, in the case of alkali metal phosphate film treatment, 3 to 5 minutes are often employed. Alternatively, if further water washing is performed after coil coating (rinse method), the composition according to the invention can also be applied to the coil. In the case of coil coating, the metal coil is preferably contacted with the aqueous composition for a time ranging from 1 second to 2 minutes.

  In the case of the process according to the invention, the substrate having a metal surface is in contact with the aqueous composition at a temperature in the range from 5 ° C. to 90 ° C., preferably from 15 ° C. to 70 ° C. or from 30 ° C. to 60 ° C. It is preferable to have a temperature in the range. On the other hand, it is also preferred that the aqueous composition has a temperature in the range of 35 ° C. to 70 ° C. or a temperature in the range of 45 ° C. to 60 ° C. when contacting the substrate having a metal surface. Therefore, in the case of this composition, the same temperature as in the case of the alkali metal phosphate film treatment may be used, and 50 to 55 ° C. is often used here. At temperatures in the range of 50 ° C. to 55 ° C., the most uniform chemical conversion film is formed, and the most uniform coating layer is formed even after coating.

  The aforementioned problems are solved by a coated substrate having a metal surface coated according to the invention.

Here, the film produced by the present method has a film thickness of 0.3 μm to 3 μm, and / or the total amount of zirconium or / and titanium deposited (Auflag) measured alone is: As measured by X-ray fluorescence analysis (RFA), it is in the range of 1 mg / m ² to 300 mg / m ² , or preferably in the range of 15 mg / m ² to 150 mg / m ² .

  It is further preferred here that the film produced by the method is colored, iridescent or gray. Preferably, in the film produced here, an interference color of the first or higher grade appears, or a color in which the interference color and the ionic color overlap. Their colors are the same or similar to alkali metal phosphate coatings. The color often helps to approximate the thickness and partial uniformity or / and quality of the coating. Furthermore, the coating method is particularly advantageous when this is possible with a relatively wide viewing distance.

  Especially for high quality use purposes, the conversion coating according to the invention produced by the process is subsequently water or an aqueous post-rinse solution (Nachspelloesung) with a content of silane, organic polymer or / and organic copolymer. Rinse and, if necessary, are preferably painted. Post-rinsing may be performed using an aqueous post-rinsing solution, for example, using Gardoleene® D95 having a phenolic resin content, or using silane-based Gardoleene® D6890. Good.

  Aqueous post-rinse solutions each have at least one of a) a cation selected from alkaline earth metal cations, aluminum cations, titanium cations, yttrium cations and heavy metal cations, b) organic polymers or / and copolymers, c) silanes, silanols It is particularly preferred to have a content of siloxane, siloxane or / and polysiloxane, or / and d) complex fluoride, where the complex fluoride is also the corresponding fluorine-containing acid. Here, the silane is particularly preferably an aminosilane having one, two or more amino groups and / or bissilylsilane.

  In the case of a particularly preferred method according to the invention, a film is provided with an aqueous acidic composition according to the invention, optionally followed by rinsing with water, and / or optionally after-rinsing with an aqueous composition, as such. At least one coating produced is subsequently applied at least once.

Here, in a particularly preferred method according to the invention, an aqueous acidic composition according to the invention, wherein the ^ions are calculated as TiF ₆ ²⁺ , ZrF ₆ ²⁺ or / and HfF ₆ ²⁺ or ZrF ₆ ²⁺ ZrF ₆ ^{2+ in} the form of only 0.01 g / L to 1 g / L, and Fe ²⁺ ion, Mn ion and / or Zn ion, respectively, from 0 g / L or 0.01 g / L to 1 g / L, At least one of the ions is included in a content range from 0.01 g / L to 1 g / L, and in some cases is 0.1 on the basis of the particulate SiO ₂ solid content with an average particle size of less than 0.3 μm. From 0 to 2 g / L, or / and optionally at least one surfactant substantially free of phosphate ions and substantially free of phosphonate ions 0. A coating is provided by an aqueous acidic composition according to the invention based on from 01 g / L to 10 g / L, optionally followed by rinsing with water, and / or optionally thereafter, zirconium fluoride (Zirkonium plexfluorid), And at least one coating so produced by subsequent rinsing with an aqueous composition based on an organic polymer / copolymer that is stable at a pH value of less than 6.5 can subsequently be applied at least once. it can. Owing to the surfactant content in the aqueous acidic composition according to the invention, it is possible in some cases to avoid a prior washing step.

  The conversion coating according to the present invention produced by this method preferably contains water or preferably, in particular, silane, organic polymer or / and organic copolymer content, if this coating does not contain organic polymers and organic copolymers. It may be dried without rinsing with an aqueous post-rinsing solution and optionally painted.

  The conversion coating according to the present invention produced by the present method can alternatively be used if it contains an organic polymer or / and copolymer, preferably without being coated with a primer, paint or adhesive.

  The conversion coating according to the invention produced by this method may optionally be coated at least once with a primer, paint or adhesive, optionally after rinsing at least once with water or / and an aqueous post-rinse solution. Therefore, also in those compositions, the processing process, the processing sequence, and the processing method which are the same as alkali metal phosphate membrane | film | coat processing can be used successfully as needed.

  Films produced by this method can be an excellent alternative to alkali metal phosphate films, such as iron phosphate films.

  At least one base material having a metal surface, coated according to the present invention, as a building member, as a container, as a construction member or connection member, as a deformed material member, as a radiator member, as a molded member intricately shaped, Or / and preferably used as a component in civil engineering, energy technology, vehicle manufacturing, equipment manufacturing, household appliance manufacturing or machine manufacturing.

  It was surprising that the aqueous chemical composition according to the present invention produced excellent coatings with excellent corrosion resistance, excellent coating adhesion and, in many cases, distinct colors. Here, the corrosion resistance of the steel surface is almost as good as a high-quality zinc phosphate coating, so it is not necessary to add a post-rinse solution later to improve the coating properties. Superior to the corrosion resistance of quality alkali metal phosphate coatings. Moreover, further post-rinsing solutions can be used to achieve the corrosion resistance of high quality zinc phosphate coating treatments.

  In addition, it was surprising to find a relatively easy alternative to alkali metal phosphate coating treatment that was simple, environmentally friendly and, in some cases, manufactured in exactly the same way. .

  The composition according to the invention and the method according to the invention are particularly advantageous when chemically pretreating the surface of various steel substrates used in the metalworking industry. Here, furthermore, the paintable conversion layer can be cleaned in one working step and applied at the same time, with cleaning including conversion coating treatment, rinsing with tap water and complete demineralized water. This three-stage process consisting of rinsing is quite satisfactory. In particular, bath analysis can be handled very easily. This is because accurate measurement of anions and cations is rarely necessary, since the chemical bath conditions are well revealed by the pH value and conductivity.

  The process according to the invention can be applied to a colored, iridescent, gray or colorless (as in B40) passivation layer (no paint) or a colored, iridescent, gray or colorless (as in B40) conversion coating (with paint). ) Can be used to manufacture. Essentially, the passive layer is also a film produced by chemical conversion. Therefore, the term “chemical conversion film” within the scope of the present application also includes the concept of “passivation layer”, for example, in the claims as long as no paint is applied or when no paint is applied.

  The method according to the invention can be used as an alternative to the alkali metal phosphate coating treatment or sometimes as an alternative to the zinc phosphate coating treatment. The product produced by the method according to the present invention can be used in various ways, in particular, as a building member, as a container, as a construction member or connection member, as a profile member, as a radiator member, and intricately shaped. As a molded part or / and as a component in civil engineering, energy technology, vehicle manufacturing, equipment manufacturing, household appliance manufacturing or machine manufacturing, for example as a radiator, as a stand, as a plate, as a lining (Verkleidungen) Winkel) or as a component in the vehicle or aircraft field.

Examples and comparative examples:
The subject of the present invention will be described in detail based on examples. Each example was performed using the substrates, method steps, materials and mixtures described below.

  Standard thin plate of Chemetall GmbH's St14 DC05 cold rolled steel, CRS, Gardobond® C, Gardobond® HDG / 5 from correspondingly galvanized steel, or AlMg1 AA5005 Garbond (registered) Trademark) F was used to coat. Unless otherwise stated, standard thin board Gardobond® C was used.

An aqueous chemical composition was prepared according to Table 1. The metal surface was additionally cleaned using Gardobond® Additive H7438 nonionic surfactant as the surfactant. Chemetall GmbH's alkaline SiO ₂ dispersion Gardbond® Additive H7157 stabilized with potassium hydroxide had a solids content of 20% and an average particle size of 0.2 μm. Polymer dispersion 1 AC2773 based on Albertingk acrylate had a solids content of 53%. Copolymer dispersion 2 VA294VP containing Albertingk acrylate had a solids content of 47%. The copolymer dispersion 3 AS 2084 VP containing Alberdingk acrylate had a solids content of 53%. At the end of the mixing process, the polymer, copolymer, SiO ₂ particles or / and surfactant were added separately to the previously prepared aqueous chemical composition. In individual tests, molybdenum ammonium was added.

In Examples B45 to B48, about 0.02 g / L of Fe ²⁺ content in the bath was already included due to the pickling effect of the acid conversion composition. Therefore, the content of this pickled iron was higher than in another sample with Fe ^{2+ in} the bath from less than 0.001 g / L to 0.01 g / L. In the case of B41 and B42 compositions, the iron contents listed in the table were intentionally added.

  The sheet was treated for 3 minutes at 55 ° C., which was accompanied by a cleaning effect when a surfactant was present. Thereafter, it was rinsed once with Betriebswasser and subsequently with VE water, and then the coated sheets were dried on a drying shelf at 120 ° C. for at least 10 minutes. There was a clear quality difference when different temperatures were used.

  Thereafter, one coating layer was provided on each of the sheets subjected to the chemical conversion coating treatment: Akzo Nobel Powder Coatings GmbH of epoxy polyester powder coating Interpon (registered trademark) 700 having a layer thickness of 60 μm to 80 μm, a layer of 60 μm to 80 μm Thick Mankiewicz polyurethane and isocyanate based wet paint Alexit® Monolayer, or BASF black cathode electrodeposition paint Cathoguard® 350, or 15 μm in example B3 with layer thicknesses from 15 μm to 20 μm In examples B45 to B48 with layer thicknesses up to 20 μm, BASF cathodic electrodeposition paint Cathoguard® 800 (KTL), then Daimler respectively Filler 25 μm to 30 μm, base paint 11 μm to 15 μm, and clear paint 40 μm to 50 μm per layer of automotive structure by Benz.

  The coating adhesion of the coated sample was confirmed by a cross-cut method in accordance with DIN EN ISO 2409 before or 240 hours after the weather resistance test. The corrosion resistance of the coated samples was measured with a neutral salt spray test NSS for 500 hours in a salt spray test according to DIN 50021. Here, only one paint layer was provided (unlike that commonly used in Asian and North American markets).

  Surprisingly, even after 1000 hours of the salt spray test, an extremely high corrosion resistance of 0 mm was obtained for B44.

The layer weight (Schichtgewich) was measured in terms of mg / m ² of the amount of simple zirconium deposited using a fluorescent X-ray analyzer. The elemental zirconium is the leading element for the quality of the film, and various metal deposits of zirconium are deposited depending on the metal substrate even when the aqueous composition is the same.

An example according to the present invention was compared with comparative examples VB1 and VB2 of high-quality and internationally used alkali metal phosphate coatings on cold-rolled steel Gardobond® C sheets: In a typical method step, for an alkali metal phosphate coating treatment (also called iron phosphate treatment if iron and steel materials are used), Gardobond® WH = Gardobond® A4976 is used. ZrF ₆ based post rinse solution Gardoleene® D6800 / used for 3 minutes at 55 ° C. on the steel surface for rinsing, rinsing with VE water and optionally followed by a post rinse solution for 5 minutes 6 and then dried in a drying shelf at 120 ° C. for at least 10 minutes. As an alternative, use an aminosilane-based post-rinse solution Gardoleene® D6890 with surfactant or a post-rinse solution Oxsilan® 9810/3 based on two different types of aminosilane and ZrF ₆ Or acrylate-based polymer dispersion 1 working with a post-rinse solution of AC2773 and then drying in a drying cabinet at 120 ° C. for at least 10 minutes.

  From these examples, it is clear that the aqueous chemical composition according to the invention often produces excellent films, despite the very simple composition and the slight content, It also has excellent corrosion resistance, excellent coating adhesion, and often a distinct color. With this composition, not only strongly colored films but also colorless films can be produced. The corrosion resistance on the steel surface is about the same as a high quality zinc phosphate coating treatment and is therefore far superior to the corrosion resistance of a high quality alkali metal phosphate coating treatment (eg B3 and Comparison with VB1).

  In comparative example VB2, the film properties were confirmed for the first time after the additional second conversion coating treatment (different from the example according to the invention). Furthermore, the adhesion of the coating on the steel surface is as good as that of a high-quality zinc phosphate coating treatment, and is therefore clearly much superior to the coating adhesion of a high-quality alkali metal phosphate coating treatment. Are better. Furthermore, the aqueous chemical composition according to the present invention has a sufficiently environmentally friendly composition, is advantageous for occupational health, and does not contain phosphate ions.

  If a post-rinse solution, for example a post-rinse solution having a content of silane, organic polymer or / and organic copolymer, is used after the conversion coating treatment according to the invention and after rinsing with water at least once, on the steel surface: A coating adhesion that was at least as good as that of a high-quality zinc phosphate coating was obtained, and corrosion resistance that was at least as good as that of a zinc phosphate coating was also obtained.

  In general, the acidic aqueous chemical composition according to the present invention is suitable as an alternative to alkali metal phosphate coating treatment on various metal substrate surfaces, and for iron phosphate coating treatment of iron surfaces and steel surfaces. It has been found that it is not only suitable for alternative processing. Now that the multi-metal performance in further processing has been found, a mixture of different metal surfaces can be processed in the same bath simultaneously or sequentially.

When exchanging ZrF ₆ and TiF ₆ , especially on steel, corrosion protection may be slightly impaired in some cases compared to the confirmed layer properties.

  If only zinc is used as the added heavy metal cation, a high quality coating will result even if the coating contains unexpectedly very little zinc content and no phosphate ions are added. It was. When only manganese was used as the heavy metal cation, a high quality film was produced even if the manganese content of the film was also unexpectedly very small and even if phosphate ions were not added. When manganese and zinc were used at the same time, a slight hindrance resulted partially when no phosphate ions were added compared to using only one of their heavy metal cations. .

High quality films were also produced when only Fe ²⁺ was used as the heavy metal cation, or when Fe ²⁺ was used in addition to Mn ions and / or Zn ions. Here, Fe ²⁺ from the base material can be additionally supplied from the surface of the base material containing iron by a pickling process accompanying reaction from the bath. However, in that case, Fe ²⁺ is oxidized to Fe ³⁺ by stirring the bath and removed from the bath as a reactive component. Despite the addition of Fe ²⁺ , in many cases the Fe ²⁺ steady concentration is in the range of Fe ²⁺ from 0.025 g / L to 0.1 g / L, as is the case with examples B41 and B42. It is.

  For example, when the coating treatment of a large number of substrates continues for a relatively long period of time, some of the main components and alloy components can be pickled in the acidic aqueous chemical composition and partially accumulate in the bath composition. In that case, in particular, a plurality of cations are often present simultaneously in the bath, which can influence the composition of the film and, as a side effect, its properties.

When no heavy metal cations were added as in Comparative Examples VB3 and VB4, a relatively unsuitable film was often produced. Zn and Mn are deposited in so small amounts that they are not measurable with respect to measurement by X-ray fluorescence analysis compared to Zr. However, Zr is a main component of the layer, and may exist as, for example, (Zr (OH) _x F _y ). Zn often acts as a fluoride ion scavenger at the metal-film interface, which allows fewer fluoride ions to be incorporated in the layer, which is better according to the applicant's understanding. Result. Zn and Mn are only a minor component of the layer and can only be detected in more detail by analysis using photoelectron spectroscopy XPS / ESCA.

  The properties of the films produced are often best when the amount of Zr deposition is highest in comparable tests. However, the amount of Zr adhesion varies depending on the types of steel and the same type of steel having different surface characteristics.

  In the test, a non-ionic surfactant was also added, which further improved the cleanliness of the metal surface of the CRS Gardbond® C standard sheet used. Therefore, the preliminary cleaning process could be omitted. By contrast, the absence of a surfactant adds to the lack of cleaning of the metal surface, possibly increasing the risk of adversely affecting the layer properties. Did not occur.

  It should be noted that the coating may easily peel off if the amount of molybdate ion added is relatively large.

The addition of organic polymers, organic copolymers and SiO ₂ nanoparticles is particularly effective. It has to be noted here that if the addition amount exceeds 0.5 g / L, bubbles and deposits (Verkrustungen) do not appear to interfere with the injection nozzle and the inner wall.

Claims (20)

A method of coating a metal surface with an acidic aqueous chemical composition that is a solution or dispersion, the composition comprising:
In the form of ions, TiF ₆ ²⁺ , ZrF ₆ ²⁺ or / and HfF ₆ ²⁺ , when calculated as ZrF ₆ ²⁺ , total 0.01 g / L to 1 g / L,
Fe ²⁺ ion, Mn ion or / and Zn ion, 0 g / L or 0.01 g / L to 1 g / L, respectively, provided that Mn ion and Zn ion range from 0.1 g / L to 0.6 g / L, respectively Is included in the content of
Organic polymer or / and copolymer stable at a pH of less than 6.5 From 0 g / L or 0.01 g / L to 2 g / L based on solids content,
From 0 g / L or 0.01 g / L to 2 g / L based on the particulate SiO ₂ solid content with an average particle size of less than 0.3 μm,
At least one surfactant from 0.01 g / L to 10 g / L,
When an anion selected from the group consisting of carbonate ion, nitrate ion and sulfate ion, provided that CO ₃ ²⁺ or SO ₄ ²⁺ is present, these are converted to NO ₃ ⁺ and from 0.05 g / L Including up to 10 g / L,
The content of molybdate ions calculated as MoO ₄ ²⁺ and / or the content of P-containing oxyanions calculated as PO ₄ ³⁺ are each less than 0.1 g / L, and the acidic aqueous chemical composition The method as described above, wherein the composition has a pH value in the range of 2.5 to 6.5. The method of claim 1, wherein the acidic aqueous chemical composition further comprises a total of 0.03 g / L to 5 g / L of lithium, sodium or / and potassium ions,
Ammonium ion from 0 g / L or 0.05 g / L to 5 g / L,
From a total of 0.05 g / L to 0.3 g / L of Co ions or / and Ni ions,
Chlorate ion calculated as ClO ₃ ⁻ , nitrite ion calculated as NO ₂ , and / or peroxide ion calculated as H ₂ O ₂ , respectively, from 0 g / L or 0.01 g / L to 0.8 g Up to / L,
Free fluoride ion calculated as F ⁻ from 0 g / L or 0.01 g / L to 0.5 g / L, and vanadate ion calculated as VO ₄ ³⁻ from 0 g / L or 0.01 g / L to 0 The method of claim 1 comprising up to 2 g / L.   3. A method according to claim 1 or 2, characterized in that the coating produced by the method has a layer thickness of 0.3 [mu] m to 3 [mu] m. The method according to any one of claims 1 to 3, wherein the total amount of zirconium and / or titanium measured by itself is 1 mg / m ² to 300 mg as measured by a fluorescent X-ray analyzer. / M < ² > in the above range.   5. A method according to any one of claims 1 to 4, characterized in that the coating produced by the method is colored, iridescent or gray.   6. The method according to any one of claims 1 to 5, wherein the coating produced by the method is an alternative to an alkali metal phosphate coating.   7. A method according to any one of claims 1 to 6, wherein the bath composition is prepared by diluting one or two concentrates and water with a dilution factor ranging from 5: 1 to 40: 1. A method for producing an article.   8. The method according to any one of claims 1 to 7, wherein at least one substrate having a metal surface is contacted with the aqueous chemical composition for a time ranging from 1 second to 10 minutes. A method as described above.   9. The method according to any one of claims 1 to 8, wherein the substrate having a metal surface has a temperature in the range of 5 [deg.] C to 90 [deg.] C when in contact with the aqueous chemical conversion composition. Said method.   10. A method as claimed in any one of claims 1 to 9, wherein the aqueous chemical composition has a temperature in the range of 35 [deg.] C to 70 [deg.] C when in contact with the substrate having a metal surface. Said method.   11. The method according to any one of claims 1 to 10, wherein the substrate is washed prior to contacting the substrate with the aqueous chemical composition.   12. The method according to any one of claims 1 to 11, wherein the aqueous chemical conversion composition also includes at least one surfactant, and the cleaning and chemical conversion coating are performed in the same method step. Said method characterized.   13. A method according to any one of claims 1 to 12, wherein the conversion coating produced by the method is subsequently water or an aqueous post-rinsing solution having a content of silane, organic polymer or / and organic copolymer. Rinsing and painting as described above.   14. A method as claimed in any one of claims 1 to 13, wherein the conversion coating produced by the method is followed by water or silane, organic polymer or when the coating does not contain organic polymer and organic copolymer. And / or drying without rinsing with an aqueous post-rinsing solution having an organic copolymer content and painting.   14. A method according to any one of claims 1 to 13, wherein the conversion coating produced by the method is coated with a primer, paint or adhesive when the coating comprises an organic polymer or / and copolymer. Said method characterized in that it is used without doing so.   15. The method according to any one of claims 1 to 14, wherein the conversion coating produced by the method is rinsed at least once with water or / and an aqueous post-rinsing solution, and then the primer, paint or Said method characterized in that it is coated at least once with an adhesive.   17. The method of claim 16, wherein the aqueous post-rinse solution is each at least one of a) a cation selected from alkaline earth metal cations, aluminum cations, titanium cations, yttrium cations and heavy metal cations, b). Said process characterized in that it has a content of organic polymer or / and copolymer, c) silane, silanol, siloxane or / and polysiloxane, or / and d) complex fluoride.   18. A method according to any one of claims 1 to 17, wherein the acidic aqueous chemical composition according to claim 1 or 2 is used to provide a film and then rinsed with water or / and aqueous. A process as described above, wherein the composition is post-rinsed and the at least one coating thus produced is subsequently applied at least once. Was coated by a method according to any one of claims 1 to 18, a substrate having a metal surface, as a building component, as a container, as a construction or joining components, as profile components, radiator structure Use as an element, as a complex molded part, and / or as a component in civil engineering, energy technology, vehicle manufacturing, equipment manufacturing, household appliance manufacturing or machine manufacturing. Use of the method according to any one of claims 1 to 18 as an alternative to an alkali metal phosphate coating method or a zinc phosphate coating method.