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
  • C23C22/12—Orthophosphates containing zinc cations
  • C23C22/14—Orthophosphates containing zinc cations containing also chlorate anions
• • 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
  • C23C22/18—Orthophosphates containing manganese cations
  • C23C22/182—Orthophosphates containing manganese cations containing also zinc cations
  • C23C22/184—Orthophosphates containing manganese cations containing also zinc cations containing also nickel 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
  • C23C22/362—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

Definitions

• the present invention relates to a process for phosphating a metal surface to be coated with a coating composition. More particularly, it relates to a process for forming a phosphate film on a metal surface, which is specifically suitable for cationic electro-coating and is excellent in film adhesion, corrosion resistance and especially hot brine resistance, and scab corrosion resistance.
• phosphate coating by dipping the desired phosphating is only obtained by treating a metal with a phosphate solution containing a higher concentration, i.e. about 2 to 4g/l, of zinc ion, at a higher temperature (60 to 90°C) for a comparatively longer duration of time (3 ⁇ 10 minutes), and further more, thus obtained coating, having a comparatively high coating weight (3 ⁇ 5g/m2) and bad quality, is believed to be unsuitable as a base coat and especially a base coat for electrodeposition coating because of its poor adhesion , corrosion resistance, coating appearance or the like.
• the phosphating coating for cationic electrodeposition should have an increased strength as a matter of course.
• a metal surface is first treated by dipping with an acidic aqueous phosphate solution containing from 0.5 to 1.5g/l of zinc ion, from 5 to 30g/l of phosphate ion, and from 0.01 to 0.2g/l nitrite ion as main ingredients, at 40 ⁇ 70°C for 15 to 120 seconds and then treated, for the purpose of removing the remained sludge, by spraying with the same phosphate solution at 40 ⁇ 70°C for 2 to 60 seconds, to obtain a uniform and dense phosphate film with a low coating weight of 1.5 ⁇ 3g/m2, which is useful as an under coat for electrodeposition coating.
• This technique is very useful for the treatment of iron-based surface and however, is not for the treatment of zinc-based surface because of resulting a phosphate coating having inferior secondary adhesion for intermediate and top coats and brine-spraying resistance of the electrodeposited coating.
• scab corrosion resistance i.e. resistance to the formation of scabby rusts formed on iron-based surface when injured coating is repeatedly subjected to brine or dry-wet climetical changes
• hot brine resistance i.e. resistance to the formation of scabby rusts formed on iron-based surface when injured coating is repeatedly subjected to brine or dry-wet climetical changes
• an object of the invention to provide a process for forming a phosphate film on both iron-based surface and a metal surface including iron-based surface and zinc-based surface.
• Another object of the invention is to provide a process for forming a phosphate film which is suitable for coating and especially electrodeposition coating.
• a further object of the invention is to provide a process for forming a phosphate film which is excellent in scab resistance when applied on iron-based surface, excellent in hot brine resistance when applied on iron-based surface or zinc-based surface, and is excellent in secondary adhesion when applied with an intermediate or top coat thereupon.
• the abovementioned and other objects can be attained with a process for phosphating a metal surface with an acidic aqueous phosphate solution containing 0.01 to 10g/l of colloidal particles having an isoelectric point of 3 or less and an average particle diameter of 0.1 ⁇ or less.
• the invention had been made on the basis of our novel finding that the desired effects of such colloidal particles are fully attained when zinc ion, nickel ion, manganese ion and fluoride ion are present each in defined concentration range in an acidic aqueous phosphate solution.
• the advantage of the present invention is most prominently exhibited when the treatment is carried out on metal surfaces which include both an iron-based surface and a zinc-based surface, or an iron-based surface alone. However, it is likewise useful for a zinc-based surface, and thus, the present process in widely applicable to various metal surfaces, including galvanized steel plate, galvanealed steel plate, electro galvanized steel plate, electro zinc-alloy plated steel plate, complex electro galvanized steel plate and the like.
• a metal surface is first subjected to a spray treatment and/or a dip treatment with an alkaline degreasing agent at 20 ⁇ 60°C for about 2 minutes and washed with tap-water. Then, in the case of dip treatment, the washed metal is treated with a surface conditioner by spraying and/or dipping in the surface conditioner solution at a room temperature for 10 ⁇ 30 seconds, and subsequently, thus treated metal is subjected to the present process, i.e. treating the metal surface with the present acidic aqueous phosphate solution at 20 ⁇ 70°C for 15 seconds or more, by dipping and/or spraying means, and finally washed with tap-water and then with a deionized water.
• a spray treatment and/or a dip treatment with an alkaline degreasing agent at 20 ⁇ 60°C for about 2 minutes and washed with tap-water.
• the washed metal is treated with a surface conditioner by spraying and/or dipping in the surface conditioner solution at a room temperature for 10
• the zinc ion concentration in the present phosphate solution should be in a range of 0.1 to 2.0g/l and more preferably 0.3 to 1.5g/l. If the zinc ion content in said acidic phosphate solution is less than 0.1g/l, an even phosphate film cannot be formed on the iron-based surfaces, resulting an uneven, partly blue-colored film.
• the content of phosphate ion in the present acidic phosphate solution should be limited in a range of 5 to 40g/l, and preferably 10 to 30g/l.
• the content of phosphate ion in the above solution is less than 5g/l, an uneven phosphate film is apt to be formed.
• the phosphate content is more than 40g/l, no further benefits result, and it is therefore economically disadvantageous to use additional quantities of phosphate chemicals.
• the content of colloidal particles having an isoelectric point of 3 or less and an average particle diameter of 0.1 ⁇ or less should be selected in a range of 0.01 to 10g/l, preferably 0.05 to 5g/l.
• the content of such colloidal particles in the phosphate solution is less than 0.01g/l, it is unable to get the desired modification of phosphate film in full, and if the content of such colloidal particles is more than 10g/l, the desired effects tend to be lowered and hence such an excess amount is not desired.
• Average diameter of such particles should be in a range of 0.001 ⁇ to 0.1 ⁇ , the ,lower limit being the minimum diameter for colloidal dispersion and the upper limit being fixed for the intended objects and effects of improvements in scab resistance, hot brine resistance and the like.
• the isolectric point of such particles is one of the characteristics showing an electrification tendency of the particles, and electrification may vary with pH of the aqueous dispersion of said particles.
• the colloidal particles used in the present invention are acidic particles capable of being electrified in negative in an acidic aqueous phosphate solution.
• colloidal particles having an isoelectric point of more than 3 are used in the present phosphate solution, these particles are aggregated, resulting sludges, and the intended objects of modification of phosphate film can not be attained therewith.
• a phosphating accelerator one or more of the following may be advantageously used:
• the sources of the ingredients of the present phosphate solution may be satisfactorily used; as the zinc ion sources, zinc oxide, zinc carbonate, zinc nitrate and the like; as the phosphate ion sources, phosphoric acid, zinc phosphate, manganese phosphate and the like.
• silic particles e.g. Snow Tex O, trademark, Nissan Kagaku Kogyo K.K., particle diameter 10 ⁇ 20m ⁇ , isoelectric point 2
• Silica alumina particles e.g. Snow Tex AK, trademark, Nissan Kagaku Kogyo K.K., average diameter 10 ⁇ 20m ⁇ , isoelectric point 3 or less
• Silica-Titania particles e.g. Ceramica U-1000, trademark, Nichiban Kenkyusha, isoelectric point 3 or less
• Silica-Zirconia particles e.g. Ceramica G-1500, trademark, Nichiban Kenkyusha, isoelectric point 3 or less
• antimony oxide e.g. A-1550, trademark Nissan Kagaku Kogyo K.K., average diameter 20 ⁇ 50m ⁇ , isoelectric point 3 or less
• acrylic resin particles prepared by the method of Japanese Patent Publication No. 43362/61.
• the phosphating accelerator the following may be used; sodium nitrite, ammonium nitrite, sodium m-nitrobenzene sulfonate, hydrogen peroxide and the like.
• the solution comprising at least 5g/l of phosphate ion, 0.02 to 0.5g/l of nitrite ion, at least 0.3g/l of zinc ion, the molar weight ratio of phosphate ion to nitrite ion being 1:0.7 ⁇ 1:1.3, the molar weight ratio of phosphate ion to zinc ion being 1:0.116 or less and pH of the solution being 3.3 ⁇ 3.8.
• the present phosphate solution besides the abovementioned essential ingredients, one may add particular concentrations of manganese ion, nickel ion and fluorine ion, thereby expecting the synergistic effects with the abovementioned colloidal particles.
• the content of manganese ion is preferably in a range of 0.1 to 3g/l, and most preferably 0.6 to 3g/l.
• the content of manganese ion in the present phosphate solution is less than 0.1g/l, it is unable to expect the synergistic effects of improvements in adhesion and hot brine resistance in the case of zinc-based surface, with those of colloidal particles having an isoelectric point of 3 or less.
• the content of manganese ion exceeds over 3g/l, then there is a tendency that scab resistance be lowered.
• Nickel ion content in the present phosphate solution should preferably be limited in a range of 0.1 to 6g/l, and most preferably 0.1 to 2g/l.
• the nickel content in the present phosphate solution is less than 0.1g/l, it is unable to get the synergistic effect of improving scab resistance with the present colloidal particles and when the nickel content is more than 6g/l, there is an undesirable decrease in hot brine resistance.
• Fluoride ion content should preferably be in a range of 0.05 to 4g/l, and most preferably 0.1 to 2g/l.
• the fluoride ion content in the present phosphate solution is less than 0.05g/l, it is unable to get the desired synergistic effect of improvement in scab resistance with the present colloidal particles and when the fluoride ion content is more than 4g/l, there is a tendency that the desired hot brine resistance will be lowered.
• the present phosphate solution may further contain nitrate ion, chlorate ion and the like.
• the nitrate ion content in the present phosphate solution may be in a range of 0.1 to 15g/l and preferably 2 to 10g/l, and the chlorate ion concentration is in general in a range of 0.05 to 2.0g/l and more preferably 0.2 to 1.5g/l.
• These components may be added each in singularly or in combination of 2 or more.
• the sources of these ingredients the following may be advantageously used: manganese carbonate, manganese nitrate, manganese chloride, and other manganese sources, and sodium chlorate, ammonium chlorate and other chlorate sources.
• the treating temperature with the present phosphate solution is in general 20 to 70°C and preferably 35 to 60°C. If the treating temperature is lower than 20°C, there is an unacceptable increase in the time required to produce an acceptable coating. Conversly, when the treating temperature is too high, the phosphating accelerator is decomposed and excess amounts of precipitated are formed, causing the components in the solution to become unbalanced and making it difficult to obtain satisfactorily phosphate film.
• the present phosphating treatment is effected for at least 15 seconds, preferably for about 30 to 120 seconds. Too short treating time is undesired because of resulting inferior phosphate film.
• the substrate to be phosphated is first dipped in the present acidic aqueous phosphate solution for at least 15 seconds, preferably 30 to 120 seconds and then sprayed with the present phosphate solution for at least 2 seconds, preferably 5 to 45 seconds.
• the spry treatment it is advantageous to effect the spry treatment for as long a time as is possible within the limitation of the actual production line, so as to remove the sludge adhered on the articles during the dip treatment stage.
• the present phosphating treatment includes any embodiments of dip treatment, spray treatment and combination thereof. Further more, when a metal surface is phosphated according to the present process and subsequently, subjected to a known post-treatment for a phosphating treatment, the desired effects of the present invention can be greatly enhanced.
• post-treatment solutions are aqueous partially reduced chromic acid solution as disclosed in Japanese Patent Publication No. 18217/64 (e.g. Surflite 41, trademark, Nippon Paint Co., Ltd.); aqueous solution containing water soluble zirconium compound and myoinositol phosphoric acid ester as disclosed in Japanese Patent Publication No. 17827/85 (e.g.
• Surflite 70AN-1 trademark, Nippon Paint Co., Ltd.
• an aqueous solution of polyvinyl phenol derivative as disclosed in Japanese Patent Publication (unexamined) No. 120677/82.
• Surflite 70AN-1 particular preference is given to Surflite 70AN-1.
• an iron-based surface or a metal surface containing both iron-­based surface and zinc-based surface a phosphate film which is suitable for electrodeposition coating and especially cationic electrodeposition coating and is excellent in corrosion resistance and especially scab resistance, and to form on an iron-based surface, a zinc-based surface or a metal surface including both ion-based surface and zinc-based surface, a phosphate film which is excellent in hot brine resistance and adhesion properties.
• test results are shown in Table 2.
• the test methods used are as follows:
• the amounts of colloidal particles were expressed in terms of solid content.
• Example 3 The similar coated plates were prepared as in Example 1 excepting adding a post-treatment after washing step (e) and before pure water washing step (f), the post-treatment comprising dipping the washed plate into Surflite 41 (chromic post-treating agent, 0.4wt% content, made by Nippon Paint Co.) at 50°C for 15 seconds.
• Surflite 41 chromic post-treating agent, 0.4wt% content, made by Nippon Paint Co.
• Example 7 The similar procedures as stated in Example 7 were repeated excepting substituting Surflite 70AN-1 (zirconium base post-treating agent, 1.0wt% content, made by Nippon Paint Co.) for Surflite 41.
• the test results with thus obtained coated plates were shown in Table 3.

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• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)

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• 1989
  • 1989-03-02 JP JP1050567A patent/JPH0819531B2/ja not_active Expired - Fee Related
• 1990
  • 1990-03-02 EP EP90302271A patent/EP0385806B1/fr not_active Expired - Lifetime
  • 1990-03-02 DE DE69012374T patent/DE69012374T2/de not_active Expired - Fee Related

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