Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/18—Orthophosphates containing manganese cations
  • C23C22/188—Orthophosphates containing manganese cations containing also magnesium cations
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
  • C23C22/16—Orthophosphates containing zinc cations containing also peroxy-compounds
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
  • C23C22/17—Orthophosphates containing zinc cations containing also organic acids
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
  • C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
  • C23C22/364—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also manganese cations
  • C23C22/365—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also manganese cations containing also zinc and nickel cations

Definitions

• the invention relates to a phosphating solution and a process for phosphating metal surfaces with aqueous, acidic phosphating solutions containing zinc and phosphate ions and accelerators in free or bound form, and their use as a pretreatment of the metal surfaces for subsequent painting, in particular an electrodeposition coating.
• the method is applicable for the treatment of steel, galvanized or alloy galvanized steel, aluminum, aluminized or alloy aluminised steel surfaces.
• phosphating metals are to produce metal-phosphate layers on the metal surface that are inherently resistant to corrosion and, in combination with paints and other organic coatings, contribute significantly to adhesion and resistance to corrosion undercutting.
• Such phosphating processes have long been known in the art.
• the low-zinc phosphating in which the phosphating relatively low levels of zinc ions of z. B. have 0.5 to 2 g / l.
• Phosphating solutions usually contain so-called “accelerators” which, on the one hand, accelerate film formation by “depolarizing” them by oxidizing the elementary hydrogen formed during the pickling attack to metal, although certain accelerators, such as hydroxylamine, can also alter the shape Oxidizing accelerators also cause iron (II) ions formed in the pickling reaction on steel surfaces to be oxidized to the trivalent state, so that they precipitate as iron (III) phosphate.
• accelerators such as hydroxylamine
• WO 97/16581 discloses a process for phosphating steel, galvanized or alloy galvanized steel and / or aluminum or its alloys by treatment with a zinc phosphating solution by dip, spray or spray dipping, characterized in that the zinc phosphating solution has a maximum nitrate ion content of 0, 5 g / l and is free of manganese, nickel and cobalt ions and that they contain 0.3 to 2 g / l of zinc ions,
• the phos- phating solution if it contains hydroxylamine as the sole accelerator, should preferably additionally contain one or more aliphatic hydroxycarboxylic acids having 3 to 6 C atoms in a total amount of 0.5 to 1.5 g / l.
• These hydroxycarboxylic acids are preferably selected from lactic acid, glycolic acid, tartronic acid, malic acid, tartaric acid and citric acid.
• EP 154367 describes a zinc phosphating solution which contains nitrobenzenesulfonate as an accelerator and which may further contain citrate or titrate.
• EP 287133 discloses a zinc phosphating solution containing as essential accelerator 5 to 30 g / l of nitrate. Preferably, it further contains 0.5 to 5 g / l of iron (II), precluding the presence of an oxidizing accelerator such as H 2 O 2 .
• This phosphating solution may additionally contain up to 3 g / l of tartaric acid or citric acid.
• a phosphating solution which contains nitrate ions, iron (II) - or iron (III) ions and at least one organic Chelatkomplextruckner.
• This complexing agent may be a polyhydroxycarboxylic acid such as tartaric acid or citric acid.
• WO 94/13856 deals with zinc phosphating solutions, in particular for belt processes, which have a relatively high content of free acid (for definition: see below) of 2 to 6 points.
• These phosphating solutions contain water-soluble organic acids whose dissociation constant is between the dissociation constants of the first and second stages of phosphoric acid.
• a whole series of corresponding acids are listed, including citric acid.
• the phosphating solution can be an oxidizing agent selected from nitrite, chlorate, bromate, hydroxylamine, organic aromatic nitro compounds and hydrogen peroxide or peroxide compounds.
• the concentration of the organic acids should be in the range of 0.008 to 0.15 mol / l, the concentration of hydrogen peroxide in the range of 0.01 to 0.1 g / l. In the embodiments, neither hydrogen peroxide nor citric acid are used.
• the layer weight of the metal phosphate layer should be, for example, on steel in the range of 1 to 3, preferably in the range of 1, 5 to 2.5 g / m 2 .
• the present invention represents a compromise between these different requirements.
• the present invention relates, in a first aspect, to an acidic, aqueous phosphating solution containing from 0.2 to 3 g / l of zinc (II) ions,
• Hydrogen peroxide-releasing substance a total of 0.3 to 1, 5 g / l, preferably 0.5 to 1 g / l of one or more aliphatic chelating carboxylic acids having 2 to 7, preferably - -
• Chelating carboxylic acids are to be understood as meaning carboxylic acids having at least two functional groups (including the carboxyl group) which have atoms with at least one free electron pair.
• Complexes with metal ions suitable for this purpose, in particular with transition metal cations, can be formed via the lone pairs of electrons of these functional groups.
• Chelate complexes are formed when at least two such functional groups of the same carboxylic acid coordinate to the same metal cation, forming an annular structure including the metal cation.
• these rings, including the metal cation have five to seven atoms.
• the aliphatic chelating carboxylic acids have at least two carboxyl groups and at least one hydroxy group which is not part of a carboxyl group. They may be selected, for example, from tartronic acid, malic acid, tartaric acid and citric acid.
• carboxylic acids are present in the phosphating solution as free acids or as acid anions depends on the acid constant of the carboxylic acid and on the pH of the phosphating solution. In general, a chemical balance will be established between free carboxylic acid and carboxylic acid anions. The above concentrations are by total concentration, i. as the sum of the concentrations of the free carboxylic acid and its anions.
• Values of the free acid between about 0.3 and 1.0 points and the total acid between about 15 and about 35 points are useful in this invention.
• the phosphating solution according to the present invention has a higher "free acid” content than a maximum of one point, there is an increasing risk of rusting on freshly phosphated steel surfaces when they are slowly drying in air, which may be the case, for example, after immersion phosphating the freshly phosphated parts are transported slowly or for a long time or when the system stops while freshly phosphated parts are in the air, the restriction of the "free acid” according to the invention reduces this danger and thereby increases the operational safety.
• the phosphating solution preferably contains 20 to 35 mg / l of hydrogen peroxide or an equivalent amount of a hydrogen peroxide-releasing substance.
• the phosphating solution additionally contains one or more cations which are incorporated into the crystalline phosphate layer. Accordingly, it is also preferred in the context of the present invention for the phosphating solution additionally to contain one or more of the following cations:
• the phosphating solution is low in nickel or preferably nickel-free.
• the positive effect of nickel ions on paint adhesion and corrosion protection is then taken over by the ecologically less questionable copper ions.
• This embodiment is characterized in that the phosphating solution contains 0.1 to 4 g / l of manganese (II) ions, 0.002 to 0.2 g / l of copper ions and not more than 0.05 g / l of nickel ions.
• the phosphating solution contains 0.1 to 4 g / l manganese (II) ions and 0.1 to 2.5 g / l nickel ions ,
• the content of zinc ions is preferably 0.4 to 2 g / l and more preferably 0.5 to 1.5 g / l.
• phosphating baths usually contain sodium, potassium and / or ammonium ions. Alkaline compounds of these cations are often added to phosphating solutions to adjust the "free acid".
• the weight ratio of phosphate ions to zinc ions in the phosphating baths can vary within wide limits, provided it is in the range between 3.7 and 30. A weight ratio between 10 and 20 is particularly preferred.
• nitrate content of the phosphating In the phosphating of zinc-containing surfaces, it has proved to be beneficial to limit the nitrate content of the phosphating to a maximum of 0.5 g / l. As a result, the problem of so-called specks is suppressed and the corrosion protection improved. Phosphating baths which contain less than 0.05 g / l and in particular no nitrate are particularly preferred. In the phosphatization of steel, however, nitrate contents of up to 2 g / l can be favorable.
• hydrogen peroxide can be d. H. in free form, or else in bound form, for example as ionic peroxide or in the form of peroxo compounds such as, for example, peroxodisulfuric acid, Caro's acid or peroxo phosphoric acid.
• Another carrier for hydrogen peroxide in bound form is sodium perborate.
• the phosphating solution at the place of use could be assembled by dissolving the individual components in water to the application concentration. However, this does not happen in practice. Rather, it is customary to provide concentrates for the first batch and for supplementing a phosphating solution. The batch concentrate is then diluted at the point of use with water to the use concentration, usually the content of free acid and / or the pH must be adjusted to the application. Free acid content ranges have already been indicated above. The pH is then usually between 2.7 and 3.6. Supplementary concentrates are used to maintain the active ingredients in a phosphating solution during operation in the desired range.
• the present invention also relates to an aqueous concentrate which after diluting with water by a factor of between 10 and 100 and optionally adjusting the level of free acid to a maximum of one point, the pH to a range between 2.7 and 3.6 and optionally adjusting the concentration of H 2 O 2 or a hydrogen peroxide-releasing substance to the desired range results in a phosphating solution described above.
• Phosphatizing bath concentrates are generally rendered strongly acidic for reasons of stability, so that the content of free acid after dilution with water is initially significantly above the desired working range.
• an alkaline substance such as caustic soda or sodium carbonate solution, the value of the free acid is lowered to the desired range.
• H 2 O 2 or a H 2 O 2 - releasing substance is usually required because these accelerators are not sufficiently stable in the concentration required for a Phosphatierbad- concentrate in such a concentrate.
• the concentrate according to the invention contains the active ingredients of the phosphating solution with the exception of H 2 O 2 or a H 2 O 2 - releasing substance.
• the present invention relates to a process for phosphating metal surfaces of steel, galvanized or alloy galvanized steel and / or aluminum, by spraying or dipping the metal surfaces or by a combination thereof for a time between 3 seconds and 8 Minutes with a phosphating solution described above in contact.
• the temperature of the phosphating solution is in the range of about 30 to about 70 and in particular from about 40 to about 60 0 C. In particular, temperatures in the range of 50 to 55 ° C are set in practice.
• the method according to the invention is suitable for phosphating surfaces of steel, galvanized or alloy-galvanized steel, aluminum, aluminized or alloy-aluminized steel.
• the materials mentioned can - as is increasingly common in the automotive industry - also exist side by side.
• parts of the body can also consist of pre-treated material, as it arises, for example, after the Granocoat ⁇ process.
• the base material is first pretreated and then coated with a weldable coating of an organic resin.
• the phosphating process according to the invention then leads to phosphating at damaged areas of this pretreatment layer or on untreated backsides.
• the method can be used in particular in the automotive industry, where treatment times are usually between 1 and 8 minutes. It is intended in particular for the treatment of said metal surfaces before painting, in particular before a cathodic electrodeposition coating, as is customary in the automotive industry.
• the phosphating process can be seen as a partial step of the technically customary pretreatment chain. In this chain, phosphating is usually preceded by the steps of cleaning / degreasing, intermediate rinsing and activating, wherein the activation is usually carried out with titanium phosphate-containing activating agents. However, the activation can also be carried out with a suspension of finely divided ( ⁇ 5 ⁇ m) particulate phosphates of divalent or trivalent metals in an alkali metal phosphate solution. This activation method is described for example in EP 1368508.
• the phosphating according to the invention may, optionally after an intermediate rinse, be followed by a passivating after-treatment.
• a passivating aftertreatment chromic acid-containing treatment baths were widely used. For reasons of labor and environmental protection as well as disposal reasons, however, there is a tendency to replace these chromium-containing passivation baths with chrome-free treatment baths.
• an intermediate rinse with demineralized water is generally carried out.
• the phosphating methods according to the invention and comparison methods were tested on cold-rolled steel sheets, such as those used in the automotive industry.
• the following process, which is customary in bodywork, was carried out as a dipping process:
• Free acidity 0.7 points or (as a comparison) 1, 2 points
• Comparative Examples 16 and 17 show that when using nitrite or hydroxylamine as accelerator, a satisfactory phosphating result is obtained even without the addition of a chelating carboxylic acid. However, if it is desired, for example for ecological reasons, to use H2O2 as the accelerator, a satisfactory phosphating result is obtained with a free acid content of at most one point only with the addition of the chelating carboxylic acid. If the content of "free acid” is increased to 1, 2 points, rust formation also occurs with a combination of citric acid / H 2 O 2 (compare 13 to 15).
• Figure 1 shows scanning electron micrographs of a phosphate layer according to Comparative Example 6
• Figure 2 Scanning electron micrographs of a phosphate layer according to Example 1. In the latter case, significantly smaller and more compact phosphate crystals are obtained in a closed phosphate layer ,
• Illustration 1

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=37668277

Family Applications (1)

Country Status (7)

Families Citing this family (10)

Citations (8)

Family Cites Families (15)

• 2005
  • 2005-09-30 DE DE102005047424A patent/DE102005047424A1/de not_active Ceased
• 2006
  • 2006-08-16 CN CN2006800364618A patent/CN101278075B/zh not_active Expired - Fee Related
  • 2006-08-16 EP EP06776869A patent/EP1929070A1/de not_active Withdrawn
  • 2006-08-16 WO PCT/EP2006/008063 patent/WO2007039015A1/de active Application Filing
  • 2006-08-16 RU RU2008116542/02A patent/RU2428518C2/ru not_active IP Right Cessation
• 2008
  • 2008-03-26 US US12/055,984 patent/US20090071573A1/en not_active Abandoned
  • 2008-03-28 ZA ZA200802778A patent/ZA200802778B/xx unknown

Patent Citations (8)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events