EP0793737B1 - Procede et composition de revetement par conversion a base de phosphate de zinc - Google Patents

Procede et composition de revetement par conversion a base de phosphate de zinc Download PDF

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Publication number
EP0793737B1
EP0793737B1 EP95942466A EP95942466A EP0793737B1 EP 0793737 B1 EP0793737 B1 EP 0793737B1 EP 95942466 A EP95942466 A EP 95942466A EP 95942466 A EP95942466 A EP 95942466A EP 0793737 B1 EP0793737 B1 EP 0793737B1
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Prior art keywords
conversion
treatment
coating
ions
bath
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EP95942466A
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German (de)
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EP0793737A1 (fr
EP0793737A4 (fr
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Yasuhiko Nagashima
Hitoshi Ishii
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Henkel Corp
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Henkel Corp
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    • 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
    • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
    • C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
    • C23C22/362—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also zinc cations
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—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

  • This invention relates to zinc phosphate-based conversion treatment baths which can be applied to a variety of metal substrates, for example, steel, steel sheet, glavanized steel sheet, and the like. More particularly, this invention relates to a zinc phosphate-based conversion bath and to a surface treatment method that are able to form a fine, dense, and uniform conversion coating on metal surfaces and that are also able to induce fine-crystal formation in the conversion coating.
  • the conversion treatment baths used for zinc phosphate-based conversion treatment are essentially acidic aqueous solutions that contain zinc ions, phosphate ions, and oxidizing agent(s).
  • Nitrite salts, chlorate salts, hydrogen peroxide, organic nitro compounds, hydroxylamine, and the like, are ordinarily considered for this oxidizing agent.
  • These oxidizing agents are typically called conversion "accelerators" because they function to accelerate the conversion reactions.
  • Nitrate salts may be present in conversion baths, but - because, in the concentrations usually present in zinc phosphate-based conversion baths, nitrate ions do not exercise an oxidizing activity sufficient to convert ferrous ions substantially completely to ferric ions - nitrate ions must be distinguished from the conversion accelerators.
  • conversion accelerators during the zinc phosphate based conversion treatment of ferriferous metals is to oxidise the divalent iron ions eluting into the conversion bath to trivalent iron ions.
  • the conversion reactions are inhibited when divalent iron ions accumulate in the conversion bath during the continuous conversion treatment of ferriferous metals, and the role of the conversion accelerator in inhibiting this accumulation of divalent iron ions is thus crucial.
  • chloride salts When chlorate salts are used as conversion accelerators, chloride ions are produced as a decomposition product during conversion treatment and accumulate in the conversion treatment bath. The corrosion resistance of the metal substrate is substantially impaired when even a trace of chloride ions from the conversion treatment bath remains on the surface of the metal workpiece.
  • chlorate salts are ordinarily used in combination with another conversion accelerator, such as nitrite salts, and when used alone provide only a significantly reduced conversion reaction rate.
  • Stability in the conversion treatment bath is also a problem for the use of hydrogen peroxide as a conversion accelerator: Hydrogen peroxide is readily decomposed by oxygen dissolved in the conversion bath. In addition, hydrogen peroxide has a narrow optimal concentration range for conversion treatment, which makes it difficult to manage the conversion treatment bath. When the dissolved concentration is too high, a powdery, poorly adherent conversion coating is deposited on the metal surface.
  • French Patent Specification No. 2,410,055 concerns the use of hydrogen peroxide as a conversion accelerator in a zinc phosphate conversion coating bath but although mention is made of a peroxide precursor, this is not illustrated.
  • GB Patent Specification No. 828,916 mentions the use of a large range of oxidants including hydrogen peroxide and t-butyl peroxide.
  • Nitroguanine for example, has a low solubility in water and as a result cannot be formulated as a concentrate for addition to the conversion bath. It is also difficult to control the divalent iron ions concentration in the conversion bath using nitroguanine because this compound has a weak capacity to oxidize the divalent iron ions.
  • sodium m-nitrobenzenesulfonate provides a poor conversion performance when used by itself, and for this reason this compound must ordinarily be used in combination with another, more powerful conversion accelerator.
  • Hydroxylamine compounds are another type of nitrogenous organic compounds used as conversion accelerators. These compounds, however, in order to achieve the best results, must be added to give concentrations of at least 1,000 parts per million by weight (hereinafter usually abbreviated as "ppm") in the conversion bath, giving rise to the possibility of a large and economically undesirable consumption of the conversion accelerator.
  • ppm parts per million by weight
  • the present invention seeks to solve the problems described above for conversion accelerators. More specifically, the present invention introduces a zinc phosphate-based conversion bath for metals and a metal surface treatment method which are able to deposit a fine, dense, and uniform zinc phosphate-type conversion coating on the surface of the metal substrate and which are able to induce fine-crystal formation in the conversion coating.
  • organic peroxide conversion accelerators need not be used in combination with nitrate salts or another conversion accelerator and thereby make possible the elimination of nitrogenous compounds from the conversion bath; the use of organic peroxide conversion accelerators yields fine, dense, and uniform crystals in the coating even without the application of a surface-conditioning treatment; and the use of organic peroxide conversion accelerators results in the formation of high-quality conversion coatings on metal substrates without being subject to narrow limitations of temperature, zinc concentration and the like.
  • the present invention was developed as a result of these discoveries.
  • the invention provides an acidic aqueous phosphate conversion-coating composition for treating metal surfaces, which composition comprises water, 0.5 to 1.3 g/l zinc ions, 5 to 30 g/l phosphate ions and 50 to 1,500 ppm organic peroxide(s) as a conversion accelerator and which composition has a free acidity of 0.1 to 0.9 points.
  • treatment baths according to the present invention can also satisfy environmental regulations concerning the amount of nitrogenous compound in the effluent.
  • environmental regulations concerning the amount of nitrogenous compound in the effluent.
  • the described zinc phosphate-based surface treatment according to the invention method is preferably carried out by subjecting the preliminary degreased surface of the metal to a water rinse and consecutively thereafter to the conversion treatment.
  • the treatment is preferably carried out by contacting the metal surface with the aqueous conversion coating composition at a treatment temperature of from room temperature up to 90°C and for a period of time in the range of from 30 seconds to 15 minutes.
  • the conversion treatment bath according to the present invention When the conversion treatment bath according to the present invention is to be used to provide an underpaint coating for metals and the zinc ions concentration falls below 0.5 g/L, the resulting zinc phosphate-type conversion coating will exhibit a reduced coverage ratio, which can cause an unsatisfactory post-paint coating adherence and an unsatisfactory post-paint corrosion resistance. Zinc ions concentrations in excess cause a coarsening of the crystals in the coating, which can in particular cause a reduced post-paint coating adherence.
  • the phosphate ions concentration in the conversion bath according to the present invention is preferably 5.0 to 30.0 g/L. Obtaining a normal conversion coating can become problematic at below 5.0 g/L. No additional benefits are obtained at above 30.0 g/L, which makes such values uneconomical.
  • the phosphate ions can be generated by the addition of phosphoric acid or its aqueous solutions to the conversion bath or by dissolving a salt of phosphoric acid, such as the sodium potassium, magnesium, zinc, or the like salt, in a conversion bath.
  • the zinc phosphate-based conversion treatment bath according to the present invention is an acidic aqueous solution whose pH preferably is from 2.0 to 4.0 and more preferably from about 2.5 to 3.5.
  • orthophosphoric acid H 3 PO 4
  • H 2 PO 4 dihydrogen phosphate ions
  • HPO 4 -2 hydrogen phosphate ions
  • PO 4 3- phosphate ions
  • concentrations specified herein and those of "phosphate ions” are intended to include the stoichiometric equivalent as phosphate ions of any of the chemical species from undissociated orthophosphoric acid to completely ionized phosphate ions.
  • the free acid content, measured as described in the examples below, of the compositions according to the invention is at least, with increasing preference in the order given, 0.1, 0.3, 0.5, or 0.6 point and independently is not more than 0.9 point(s).
  • the organic peroxides used by the present invention can be classified into, for example, organoperoxides, such as ethyl hydroperoxides, isopropyl hydroperoxide, tert-butyl hydroperoxide, tert-hexyl hydroperoxide, diethyl peroxide, tert-butyl peroxymaleate, and the like, that contain a peroxy moiety without an adjacent carbonyl group; and percarboxylic acid types such as peracetic acid, monoperphthalic acid, persuccinic acid, and the like.
  • organoperoxides such as ethyl hydroperoxides, isopropyl hydroperoxide, tert-butyl hydroperoxide, tert-hexyl hydroperoxide, diethyl peroxide, tert-butyl peroxymaleate, and the like, that contain a peroxy moiety without an adjacent carbonyl group
  • percarboxylic acid types such as perace
  • Organic peroxide molecules are used at concentrations of 50 to 1,500 ppm in a conversion bath according to the invention. Acceleration of conversion film formation can become unsatisfactory when the organoperoxide concentration in the conversion bath is below 50 ppm. Accordingly, the organic peroxide molecules present in the conversion bath according to the present invention preferably contain C 1 to C 7 alkyl moieties, because a low water solubility is exhibited by organic peroxides containing aromatic or higher molecular weight alkyl moieties, and this can result in a failure to obtain a satisfactory oxidizing activity. On the other hand, no additional effect is obtained at concentrations in excess of 1,500 ppm, and such values are therefore uneconomical.
  • the instant conversion bath can produce a fine, dense, and uniform zinc phosphate-type conversion coating even in the absence of an immediately preceding surface-conditioning treatment for the specific purpose of inducing fine-crystal formation in the coating.
  • the conversion bath according to the present invention does not require the addition of nitric acid, nitrous acid, an organic nitro compound, or the like, and thus can be formulated entirely free of nitrogenous compounds. In this form it therefore offers the advantage of not requiring the inclusion of a treatment step for nitrogenous compounds in the effluent treatment process.
  • Nitrogenous compounds may be added to the conversion treatment bath according to the present invention on an optional basis, but the nitrogen concentration is preferably held to no greater than 100 ppm and more preferably to 20 ppm or less.
  • Metal ions other than the zinc ions can be added to the zinc phosphate based conversion bath according to the present invention. These metal ions can act as etchants in order to induce a uniform etch of the surface of the metal workpiece, or can act as paintability improvers when the conversion coating is being used as an underpaint coating.
  • Suitable non-zinc metal ions are exemplified by nickel ions, manganese ions, cobalt ions, iron ions, magnesium ions, calcium ions, and so forth. Each of these ions can be provided by dissolution in the treatment bath of the oxide, hydroxide, carbonate, sulfate, phosphate, or the like, of the corresponding metal.
  • Fluoride ions or complex fluoride ions e.g., fluosilicate ions, fluozirconate ions, and the like, can be used as etchant. These ions can be provided, for example, by dissolving in the conversion treatment bath one or more of the following fluorine compounds: hydrofluoric acid, fluosilicic acid, fluozirconic acid, fluotitanic acid, and the corresponding metal salts (e.g., sodium, potassium, magnesium).
  • fluorine compounds hydrofluoric acid, fluosilicic acid, fluozirconic acid, fluotitanic acid, and the corresponding metal salts (e.g., sodium, potassium, magnesium).
  • the following process steps preferably should be consecutively executed in the sequence given in order to form a conversion coating on metal surfaces using a zinc phosphate based conversion bath according to the present invention: alkaline degreasing, a water rinse, treatment with the zinc phosphate-based conversion bath, and a water rinse.
  • the degreasing and water rinse processes may themselves each be implemented as multistage processes.
  • a deionized water rinse is preferably used for the final water rinse when the conversion coating will be used as an underpaint coating.
  • the conversion coating when the conversion coating is produced on a metal surface for use as an underpaint coating, it is preferred that the conversion treatment be immediately preceded by a surface conditioning process using a colloidal titanium-containing surface conditioner for the purpose of inducing fine-crystal formation in the coating.
  • Metals subjected to the above-described conversion treatment can be painted after the final water rinse as described above or after a drying step that follows the final water rinse.
  • the metal workpiece is preferably subjected to a pickling step for purposes of descaling.
  • the lubricity of the coating can be improved even further by a soap treatment (lubrication treatment) after formation of the conversion film.
  • the desired coating can be, and preferably is, formed by conversion treatment at a treatment temperature from about room temperature to about 60 °C and at a treatment time from about 0.5 minute to about 5 minutes.
  • the desired coating can be, and preferably is, formed by conversion treatment at a treatment temperature from about 50 °C to about 90 °C and at a treatment time from about 1 minute to about 15 minutes.
  • test materials were (1) 0.8 mm-thick cold-rolled steel sheets (SPCC-SD, abbreviated below as "SPC”) and (2) galvanized steel sheets (abbreviated below as “plated”) prepared by the zinc electroplating (20 g/m 2 ) of the aforementioned cold-rolled steel sheets. These were in each case cut to 70 x 150 mm and subjected to treatment in the working and comparative examples described below.
  • SPCC-SD cold-rolled steel sheets
  • plated galvanized steel sheets
  • the free acidity in the zinc phosphate-based conversion baths in Examples 1 to 8 and Comparative Examples 1 to 4 was adjusted to specific values using sodium hydroxide.
  • the free acidity was measured by titrating 10 milliliters (hereinafter usually abbreviated as "mL") of the particular treatment bath to neutrality with 0.1 N aqueous sodium hydroxide, using bromophenol blue as the indicator.
  • mL milliliters
  • bromophenol blue as the indicator.
  • the number of mL of the 0.1 N aqueous sodium hydroxide required for the color change from yellow to blue was determined and is reported as "points" of free acidity.
  • the fluoride ions concentration in the conversion bath was measured using a fluoride sensitive electrode.
  • the appearance of the coatings was inspected visually, and the morphology and size of the grains in the conversion coating was evaluated by inspection with a scanning electron microscope (SEM).
  • tert-butyl hydroperoxide organoperoxide component
  • conversion coating weight was 1.2 g/m 2 .
  • the coating crystals were plates with an average grain size of 6 micrometers.
  • the conversion coating was grayish black and was uniform, fine, and dense.
  • a galvanized steel test sheet was subjected first to the same surface conditioning treatment as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1.
  • the resulting conversion coating weight was 2.8 g/m 2 .
  • the crystals were plates with an average grain size of 4 micrometers.
  • the conversion coating was grayish white and was uniform, fine, and dense.
  • a cold-rolled steel test sheet was subjected first to the same surface-conditioning treatment as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1, except that the organoperoxide addition consisted of 80 ppm tert-butyl hydroperoxide and the free acidity was adjusted to 0.6 point.
  • the resulting conversion coating weight was 0.9 g/m 2 .
  • the coating crystals were plates with an average grain size of 8 micrometers.
  • the conversion coating was grayish black and was uniform, fine, and dense.
  • a cold-rolled steel test sheet was subjected first to the same surface conditioning treatment as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1, except that 1,200 ppm of tert-butyl hydroperoxide was added as the organoperoxide and sufficient 65.5% nitric acid was added to give a nitrogen component content of 500 ppm.
  • the free acidity of the conversion bath was adjusted to 0.9 point.
  • the resulting conversion coating weight was 1.1 g/m 2 .
  • the coating crystals were plates with an average grain size of 7 micrometers.
  • the conversion coating was grayish black and was uniform, fine, and dense.
  • a cold-rolled steel test sheet was subjected to conversion treatment as in Example 1, except that there was no surface-conditioning treatment and only 400 ppm of tert-hexyl hydroperoxide was added as the organoperoxide.
  • the free acidity was adjusted to 0.9 point.
  • the resulting conversion coating weight was 1.0 g/m 2 .
  • the coating crystals were plates with an average grain size of 6 micrometers.
  • the conversion coating was grayish black and was uniform, fine, and dense.
  • a cold-rolled steel test sheet was subjected first to the same surface conditioning treatment as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1, except that 100 ppm of peracetic acid was added as the organoperoxide, and the free acidity was adjusted to 0.6 point.
  • the resulting conversion coating weight was 1.3 g/m 2 .
  • the coating crystals were plates with an average grain size of 10 micrometers.
  • the conversion coating was grayish black and was uniform, fine, and dense.
  • a cold-rolled steel test sheet was subjected to conversion treatment using the same conversion bath as in Example 1, except that the surface conditioning treatment was not used, 500 ppm of tert-butyl hydroperoxide was added as the organoperoxide, and the free acidity was adjusted to 0.6 point.
  • the resulting conversion coating weight was 1.1 g/m 2 .
  • the coating crystals were plates with an average grain size of 10 micrometers.
  • the conversion coating was grayish black and was uniform, fine, and dense.
  • Composition of the conversion bath phosphate ions 15 g/L (from addition of 75 % phosphoric acid) zinc ions 1.3 g/L (from addition of zinc oxide) nickel ions 1.0 g/L (from addition of nickel nitrate) manganese ions 0.5 g/L (from addition of manganese carbonate) fluoride ions 100 ppm (from addition of 55 % hydrofluoric acid) nitrate ions 7.2 g/L (from addition of sodium nitrate and nickel nitrate) (nitrogen concentration 1.4 g/L).
  • tert-butyl hydroperoxide organoperoxide component
  • conversion coating weight was 1.1 g/m 2 .
  • the coating crystals were plates with an average grain size of 5 micrometers.
  • the conversion coating was grayish black and was uniform, fine, and dense.
  • a cold-rolled steel test sheet was subjected to the same surface conditioning treatment as in Example 1 and was then submitted to the same conversion treatment as in Example 1, except that the organoperoxide addition consisted of 5 ppm of tert-butyl hydroperoxide.
  • the conversion coating weight was 0.5 g/m 2 , and the development of yellow rust was observed.
  • a galvanized steel test sheet was subjected to conversion treatment as in Example 1, except that the organoperoxide addition consisted of 5 ppm of tert-butyl hydroperoxide.
  • the conversion coating weight was 0.9 g/m 2 , the average grain size was 15 micrometers, and the coating was sparse.
  • a cold-rolled steel test sheet was subjected to conversion treatment as in Example 8, except that there was no surface-conditioning treatment and 150 ppm of nitrite salt was added to the conversion bath in place of the organoperoxide.
  • the conversion coating weight was 0.1 g/m 2 , which indicated that almost no conversion coating deposition had occurred. Yellow rust had developed over the entire surface.
  • a cold-rolled steel test sheet was subjected to conversion treatment as in Example 1, except that sodium chlorate was added to the conversion bath in place of the organoperoxide.
  • the sodium chlorate was added to give a chlorate ions concentration of 1.5 g/L.
  • the conversion coating weight was 0.9 g/m 2 .
  • the coating crystals were columnar and the average grain size was 15 micrometers.
  • the conversion coating was sparsely deposited, and yellow rust was observed.
  • the organoperoxide concentrations used in Examples 1 to 8 were 50 to 1,500 ppm. It was thereby demonstrated that this concentration range produced a good-quality conversion coating on cold-rolled steel sheet as well as galvanized steel sheet. A uniform, dense, and fine coating was obtained even when the surface conditioning treatment was not used.
  • Comparative Examples 1 and 2 used organoperoxide concentrations below 50 ppm, and it was found that in these cases the oxidation activity by the conversion accelerator was inadequate, resulting in the deposition of scattered coating crystals. The uniformity of the coating on the basis metal was therefore diminished.
  • Comparative Examples 3 and 4 used non-organoperoxide conversion accelerators.
  • a nitrite salt was used as the conversion accelerator and no surface-conditioning treatment was carried out. It was found that in this case conversion coating deposition was entirely absent.
  • a chlorate salt was used by itself as the conversion accelerator in Comparative Example 4. It was found that in this case the conversion reaction rate was substantially slowed.
  • the zinc phosphate-based conversion bath according to the present invention for application to metal substrates contains 50 to 1500 ppm of organoperoxide as conversion accelerator. In consequence thereof, this bath yields uniform, fine, and dense conversion coatings with coating weights appropriate for the intended applications. This bath at the same time also acts to induce fine crystal formation in the conversion coating. As a result, the bath has such good effects that a surface-conditioning treatment is no longer a necessity.

Claims (7)

  1. Composition acide aqueuse de revêtement par conversion à base de phosphate pour traiter des surfaces métalliques, cette composition comprenant de l'eau, de 0,5 à 1,3 g/l d'ions zinc, de 5 à 30 g/l d'ions phosphate et de 50 à 1 500 ppm de peroxyde(s) organique(s) en tant qu'accélérateur de conversion et cette composition ayant une acidité libre de 0,1 à 0,9 points.
  2. Composition selon la revendication 1, dans laquelle la concentration en composés contenant de l'azote, calculée comme azote, est inférieure à 20 ppm.
  3. Composition selon les revendications 1 ou 2 dans laquelle le ou les peroxydes organiques est ou sont des peroxydes organiques substitués par un alkyle dans lesquels les substituants alkyle contiennent de 1 à 7 atomes de carbone.
  4. Composition selon l'une quelconque des revendications précédentes ayant une valeur du pH dans la plage allant de 2,0 à 4,0.
  5. Composition selon la revendication 4 ayant une valeur du pH dans la plage allant de 2,5 à 3,5.
  6. Procédé pour former un revêtement par conversion de phosphate sur une surface métallique dans lequel la surface métallique est mise en contact avec une composition liquide aqueuse comme revendiquée dans l'une quelconque des revendications précédentes à une température de traitement allant de la température ambiante jusqu'à 90°C et pendant une période comprise dans l'intervalle allant de 30 secondes à 15 minutes.
  7. Procédé selon la revendication 6 dans lequel, avant la formation d'un revêtement par conversion de phosphate sur la surface métallique, celle-ci est d'abord dégraissée, puis rincée avec de l'eau et, après la formation du revêtement par conversion de phosphate, elle est encore rincée à l'eau.
EP95942466A 1994-12-06 1995-12-06 Procede et composition de revetement par conversion a base de phosphate de zinc Expired - Lifetime EP0793737B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP302289/94 1994-12-06
JP30228994 1994-12-06
JP30228994 1994-12-06
PCT/US1995/015227 WO1996017976A1 (fr) 1994-12-06 1995-12-06 Procede et composition de revetement par conversion a base de phosphate de zinc

Publications (3)

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EP0793737A1 EP0793737A1 (fr) 1997-09-10
EP0793737A4 EP0793737A4 (fr) 1998-03-04
EP0793737B1 true EP0793737B1 (fr) 2002-10-23

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EP95942466A Expired - Lifetime EP0793737B1 (fr) 1994-12-06 1995-12-06 Procede et composition de revetement par conversion a base de phosphate de zinc

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EP (1) EP0793737B1 (fr)
AT (1) ATE226648T1 (fr)
CA (1) CA2207179A1 (fr)
DE (1) DE69528664T2 (fr)
ES (1) ES2183891T3 (fr)
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US5888315A (en) * 1995-03-07 1999-03-30 Henkel Corporation Composition and process for forming an underpaint coating on metals
AU699822B2 (en) * 1995-03-07 1998-12-17 Henkel Corporation Composition and process for forming an underpaint coating on metals
DE102011089714A1 (de) * 2011-12-23 2013-06-27 Chemetall Gmbh Verfahren zum Bekämpfen von Mikroorganismen in Anlagen, Bädern und Spülflüssigkeiten der Oberflächentechnik mit Persäure

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2471908A (en) * 1948-04-08 1949-05-31 American Chem Paint Co Method of and material for preparing surfaces of ferriferous metals for the reception of a siccative finishing coat
US3161549A (en) * 1955-04-08 1964-12-15 Lubrizol Corp Solution for forming zinc phosphate coatings on metallic surfaces
FR1192515A (fr) * 1957-12-31 1959-10-27 Procédé pour préparer les pièces en fer ou en acier en vue de leur formage à froid
DE1095625B (de) * 1959-02-27 1960-12-22 Collardin Gmbh Gerhard Verfahren zum Phosphatieren von Metallen
GB1272772A (en) * 1968-08-16 1972-05-03 Ici Ltd Phosphating solutions
US3642541A (en) * 1969-02-12 1972-02-15 Republic Steel Corp Method for applying corrosion-resistant composite coating to ferrous metals and product resulting therefrom
NZ188918A (en) * 1977-11-29 1981-01-23 Ici Ltd Applying phosphate coating to ferrous or zinciferous metal substrate and materials therefor
US4171231A (en) * 1978-04-27 1979-10-16 R. O. Hull & Company, Inc. Coating solutions of trivalent chromium for coating zinc surfaces
DE3913089A1 (de) * 1989-04-21 1990-10-25 Henkel Kgaa Chlorat- und nitritfreies verfahren zur herstellung von nickel- und manganhaltigen zinkphosphatschichten

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WO1996017976A1 (fr) 1996-06-13
CA2207179A1 (fr) 1996-06-13
ATE226648T1 (de) 2002-11-15
EP0793737A1 (fr) 1997-09-10
EP0793737A4 (fr) 1998-03-04
DE69528664D1 (de) 2002-11-28
ES2183891T3 (es) 2003-04-01
MX9702738A (es) 1997-09-30
DE69528664T2 (de) 2003-07-03

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