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
  • C23C22/40—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 molybdates, tungstates or vanadates
  • C23C22/44—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 molybdates, tungstates or vanadates containing also fluorides or complex fluorides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
  • C23C2222/10—Use of solutions containing trivalent chromium but free of hexavalent chromium

Definitions

• the invention relates to a method for forming a protective layer which protects against corrosion and improves the adhesion for covering coatings in multimetal processes.
• metal bodies are understood, the outer surface of which does not consist of a uniform metallic material, for example steel (sheet metal), but of a close bond between two or more different metallic materials. These are connected to one another by welding, riveting, flanging, gluing, etc., using methods known and tested in the prior art.
• the use of such composite materials in certain areas of application is associated with numerous advantages, in the technical field (improvement of corrosion protection, improvement in mechanical properties during molding or use, increase in chemical resistance, etc.) or in the aesthetic sector (achieving a surface with a certain appearance, gloss effects etc.) may lie.
• Such composite materials can be, for example, material combinations from the group steel / aluminum, steel / hot-dip galvanized steel / aluminum, steel / galvanized steel, steel / aluminum / galvanized steel and steel / leaded steel.
• other material combinations are also conceivable that can be treated with the method according to the invention.
• opaque coatings are understood to be coatings which mostly consist of organic materials and serve to protect the metallic surface from damage, corrosion and also to improve the visual appearance.
• Organic coatings of this type include, for example, coating systems which are usually used for application to metallic surfaces for the purposes mentioned above.
• the pretreatment of such metallic surfaces usually has the aim of protecting the respective metal surfaces from the corrosive attack of the surrounding atmosphere for as long as possible and also of improving the adhesion of later-applied covering coatings of the type mentioned above to such metal surfaces.
• the most common types of pretreatment in technology are phosphating and chromating, the selection of the respective pretreatment process for a specific metallic surface being carried out which of the two methods gives the better results in each case.
• Further criteria for the selection of the respective pretreatment process are the types of covering coatings applied later, the process of further treatment of the respective metal body, its size and the requirements placed on the quality of the metal surfaces pretreated by the respective process; the automotive industry has proposed a standardized testing and evaluation system for such requirements, which is generally recognized.
• the pretreatment which is separated according to the type of material, for example phosphating or chromating, requires the fresh preparation of the respective treatment solutions or treatment baths, with the result that the solutions or baths not used in each case either have to be discarded or, if at all possible, stored and reused with the addition of new chemicals need to be sharpened. This is not justifiable from an economic or ecological point of view.
• the joint pretreatment of metal bodies made of steel, galvanized material and aluminum can also be carried out using so-called "non-layer-forming processes".
• Aqueous solutions based on alkali or ammonium orthophosphate and surfactants are used.
• such processes lead to the formation of layers only on steel surfaces, iron phosphates of different compositions being formed.
• Galvanized or aluminum surfaces are only degreased when treated with such solutions.
• the corrosion protection that can be achieved is significantly worse than that of a layer-forming zinc phosphating. It regularly only meets the requirements of the automotive industry for quality class II (240 h salt spray test; infiltration less than 3 mm).
• the object of the present invention was to provide a process which is suitable for industrial use, that is to say which is sufficiently fast and can be carried out under moderate reaction conditions, for the formation of protective layers which protect against corrosion and improve adhesion on metallic composite materials and which permits both different materials one by one in To pretreat baths of the same composition and to subject composite materials in baths of the same composition to a layer-forming pretreatment.
• the baths should have such a composition that all bath components contribute in an advantageous manner to the formation of layers on the respective composite materials.
• thin layers should be formed on the metal bodies, which meet the requirements in all respects with regard to corrosion protection and adhesion of subsequently applied coatings.
• aqueous solutions which contain as essential components molybdate, chromium, fluoride, phosphate, zinc and acetate, in each case in certain concentrations .
• the metallic body In the first step of the method according to the invention for forming a protective layer on metallic composite materials which protects against corrosion and improves the adhesion for covering coatings, the metallic body usually pre-cleaned in a manner known per se. For this purpose, they are usually treated with a strongly alkaline aqueous cleaner containing large amounts of alkali metal hydroxides, which is intended to degrease the metal surface and remove contaminants adhering to the surface.
• a strongly alkaline cleaner by adding surfactants to the pre-treatment solutions of the layer-forming passivation, which are described below, in the case of metallic surfaces of a certain composition, and thus effecting degreasing and pre-cleaning . In this case, pre-cleaning with an alkaline cleaner can be omitted.
• composition of the aqueous solutions with which the metallic bodies are pre-cleaned is known from the prior art and is familiar to the person skilled in the art.
• the metallic bodies are rinsed with cold water after the alkaline pre-cleaning.
• the rinsing is also carried out in a manner known to the person skilled in the art, for example in spraying or dipping or in a combined spraying / dipping process, and leaves metallic bodies on the surface of which no residues of the alkaline precleaner solution are present.
• the protective materials which improve the covering coatings are then treated with an aqueous, acidic solution, the metallic materials, in particular the metallic composite materials, the molybdate in quantities of 0.01 to 10.0 g / l, chromium in quantities of 0.01 to 10, 0 g / l, fluoride in amounts of 0.01 to 10.0 g / l, phosphate in amounts of 0.01 to 10.0 g / l, zinc in amounts of 0.005 to 1.0 g / l and acetate in Contains amounts of 0.01 to 10.0 g / l and optionally other ingredients.
• the pH of the aqueous passivation solutions is in the range from 2.8 to 4.5, preferably in the range from 3 to 3.5. At these pH values, advantageous conditioning of the metal or composite material surfaces for the layer-forming attack of the solution components is advantageously ensured.
• composition of the passivation bath solutions used in the method according to the invention can be varied within certain ranges, the concentration information of all parameters being able to be varied in the same direction or in a different direction.
• an aqueous passivation solution which preferably contains molybdate (MoO42 ⁇ ) in amounts of 0.33 to 0.35g / l and / or chromium (Cr3+) in amounts from 0.76 to 0.80 g / l and / or fluoride (F ⁇ ) in amounts from 0.11 to 0.15 g / l and / or phosphate (PO43 ⁇ ) in amounts from 0.59 to 1.1 g / l and / or zinc (Zn2+) in amounts of 0.094 to 0.11 g / l and / or acetate (ethanate; CH3COO ⁇ ) in amounts of 2.0 to 2.5 g / l.
• the passivation baths it is possible to add further constituents to the passivation baths, which also have a positive effect on the result of the method.
• additional constituents for example, it is possible to add sodium glycerophosphate and / or N-cyclohexanesulfamic acid to the passivation bath.
• Both compounds act as accelerators or regulators and can be added to the passivation baths alone or in combination with one another in amounts of 0.1 to 5 g / l, preferably in amounts of 0.5 to 2.0 g / l. This ensures that the treatment times can be reduced even more.
• the bath temperatures are in the range from 35 to 40 ° C. This temperature range is clearly below the range that has to be used in the prior art for layer-forming or non-layer-forming phosphating processes (50 to 60 ° C.). This contributes to an energy-saving and therefore economical process management.
• the treatment times for the new passivation process are in a comparatively large range.
• the extremely rapid process of layer-forming passivation which may be modified by the accelerators or regulators to achieve thin layers, already shows a clear formation of a passivation layer after a treatment time of 3 s.
• the treatment times are in the range from 3 to 180 s. This is also a time that is significantly less than the treatment time of the processes known from the prior art for layer-forming or non-layer-forming passivation (60 to 180 s).
• the shorter treatment times also advantageously contribute to economical process management, since they enable the faster throughput of metal bodies through the respective baths.
• passivation solutions used in the method according to the invention are applied to the metal bodies by methods known per se from the prior art. These can preferably be spray processes, immersion processes or combined spray / immersion processes, all of which can be used with equal success.
• the components described in more detail above are prepared in concentrates, the preparation usually being carried out in containers made of plastic or stainless steel.
• concentrates are then prepared by the user with no further additions of water in such a way that application concentrations of approximately 2% arise and the passivation solutions formed have contents of the individual components which are in the ranges specified above. It may be advantageous not to add the required phosphoric acid to the concentrate, but rather to add it directly to the application solution - when diluting the concentrate with water; this applies in particular if the concentrates are to be stored for a long time.
• these metal bodies are rinsed off with water, usually with demineralized water.
• the metal bodies provided with a passivating protective layer are dried in a manner also known from the prior art.
• This drying can be done in air or at an elevated temperature in an oven.
• the air in the drying oven can be pumped around or exchanged.
• the method according to the invention for forming a protective layer on metallic materials which protects against corrosion and improves the adhesion for covering coatings has numerous advantages over the methods known from the prior art.
• composite materials or different materials can be pretreated together or one after the other without the need to replace the baths or to change the systems.
• the pretreatment process can advantageously be carried out at low temperature and with short treatment times and leads to the thin coatings required for modern coating processes.
• a concentrate A was first prepared by mixing the following components in a container made of plastic or stainless steel: Water 63.85 parts by weight Chromium (III) ethanate 21.15 parts by weight Sodium glycerophosphate 5.0 parts by weight Chromium (III) fluoride ⁇ 4 H2O 2.0 parts by weight H3PO4 - 75% 4.87 parts by weight ZnO 0.13 parts by weight Sodium molybdate 3.0 parts by weight
• a surfactant mixture (concentrate B) was prepared in a container by stirring the following components: Fatty alcohol ethoxylate 20% Alkyl glucoside 20% Alkali salt of a phosphate ester 60%
• the 1% solution of concentrate A described above contains: Chromium 0.38 g / l Glycerophosphate 0.39 g / l Fluoride 0.06 g / l Phosphate 0.36 g / l Zinc 0.01 g / l Molybdate 0.20 g / l Ethanate 1.11 g / l
• a passivation solution intended for the spray treatment of metal sheets was prepared from both concentrates by 10.0 g / l of concentrate A and 3.0 g / l of concentrate B were mixed in water.
• the pH of a solution composed in this way was 3.5.
• the working temperature was 40 ° C and the treatment time 90 s.
• the sheets were then rinsed with cold water for 30 s, followed by rinsing with demineralized water for 10 s. Finally, the sheets were oven-dried at 85 ° C. for 5 minutes.
• the passivated sheets were coated with a PUR paint from Weilburger Lackfabrik.
• a varnish in the form of a so-called “Bundeswehr structure” (TL 8010-0002) was applied in a total layer thickness of the varnish layer of 85 to 100 ⁇ m.
• the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to a salt spray test in accordance with DIN 50021 for a period of 480 h.
• Cold-rolled steel sheets, hot-dip galvanized steel sheets and aluminum sheets of quality 99.5 were cleaned and degreased in an alkaline solution by spraying in 90 s at 55 ° C.
• the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to a salt spray test in accordance with DIN 50021 for a period of 480 h.
• a concentrate was first prepared by mixing the following components in a plastic or stainless steel container: Water 63.85 parts by weight Chromium (III) ethanate 21.15 parts by weight Sodium glycerophosphate 5.0 parts by weight Chromium (III) fluoride ⁇ 4 H2O 2.0 parts by weight H3PO4 - 75% 4.87 parts by weight ZnO 0.13 parts by weight Sodium molybdate 3.0 parts by weight
• a passivation solution intended for spray treatment was prepared from the concentrate by dissolving 10 g / l concentrate in water. Bath composition analogous to example 1.
• the free acid determined by titration of a 100 ml bath sample with 0.1 N sodium hydroxide solution and pH meter to 4.0, was 1.3.
• Cold-rolled steel sheets, hot-dip galvanized steel sheets and aluminum sheets of quality 99.5 were jointly subjected to the following process steps: First, the sheets were cleaned and degreased in 60 s at 55 ° C using an alkaline cleaner. Then it was rinsed with cold water for 30 s. The treatment with the passivation solution described above was then carried out by spraying at 30, 35 or 40 ° C. and treatment times of 30, 60 or 90 s. The sheets were then rinsed with cold water for 30 s, followed by rinsing with demineralized water for 10 s. Finally, the sheets were oven-dried at 85 ° C. for 5 minutes.
• the passivated sheets were coated with a PUR paint from Weilburger Lackfabrik. There was a so-called "Bundeswehr build-up" with a total layer thickness of 85 to 100 ⁇ m.
• the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to a salt spray test in accordance with DIN 50021 for a period of 480 h.
• the evaluation was carried out according to DIN 53167 / DIN 53209; the results are shown in Tables 1 to 3 below.
• a passivation solution intended for spray treatment was prepared from the concentrate by dissolving 10 g / l concentrate in water.
• the 1% solution of the concentrate described above thus prepared contains: Chromium 0.38 g / l Ethanate 1.11 g / l N-cyclohexanesulfamic acid 0.50 g / l Fluoride 0.06 g / l Phosphate 0.34 g / l Zinc 0.06 g / l Calcium 0.008 g / l Molybdate 0.20 g / l
• the free acid determined by titration of a 100 ml bath solution and pH meter to pH 4.0, was 1.3.
• Cold rolled steel sheets, galvanized steel sheets and aluminum sheets of quality 99.5 were jointly subjected to the following process steps: First, the sheets were cleaned and degreased in 60 s at 55 ° C using an alkaline cleaner. Then it was rinsed with cold water for 30 s. The treatment with the passivation solution described was then carried out by spraying at 38 ° C. and a treatment time of 30 s. The sheets were then rinsed with cold water for 30 s, followed by rinsing with demineralized water for 10 s. Finally, the sheets were oven-dried at 85 ° C. for 5 minutes.
• the sheets passivated in this way were dip-coated cathodically with an electro dip coating from Herberts.
• the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to a salt spray test in accordance with DIN 50021 for a period of 480 h.
• Example 3 The concentrate described in Example 3 was produced. A solution intended for immersion treatment was prepared from this concentrate by dissolving 20 g / l of the concentrate in water.
• the bath composition of the solution can be derived from Example 3. Bath concentrations that are twice as high are mentioned here.
• the pH of such a solution is 3.3.
• Cold-rolled steel sheets, aluminum sheets and hot-dip galvanized steel sheets were subjected to the following processes together: First, the sheets were cleaned and degreased with an alkaline cleaner by immersion for 5 min at 60 ° C. Then it was rinsed in cold water for 2 min. Then the immersion treatment with the described passivation solution was carried out at 38 ° C. and a treatment time of 2 min. The sheets were then rinsed in cold water for 2 minutes. This was followed by a rinsing in demineralized water for 10 s. Finally, the sheets were oven-dried at 85 ° C. for 5 minutes and sheets passivated in this way were coated with an epoxy powder from BASF. The sheets were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50021 for a period of 480 hours.
• Example 3 The concentrate described in Example 3 was produced. A solution intended for spray treatment was prepared from this concentrate by dissolving 15 g / l concentrate in water. The concentration of a bath mixture according to Example 5 corresponds to one and a half times the concentration according to Example 3. The total number of points, titrated on a 100 ml bath sample with 0.1 N sodium hydroxide solution and pH meters up to 8.5, was 19.
• the free acid determined by titration of a 100 ml bath sample with 0.1 N sodium hydroxide solution and pH meter to 4.0, was 1.9.
• Leaded steel sheets were subjected to the following procedures: First, the sheets were cleaned and degreased in 60 s at 55 ° C using an alkaline cleaner. Then it was rinsed with cold water for 30 s. The treatment with the passivation solution described was then carried out by spraying at 38 ° C. and a treatment time of 60 s. It was then rinsed with cold water for 30 s, followed by a rinsing with demineralized water for 10 s. Finally, the sheets were oven-dried at 85 ° C. for 5 minutes.
• the passivated sheets were coated with a PUR varnish from Winkelmann.
• the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to a salt spray test for a period of 480 hours.
• Leaded steel sheets were cleaned and degreased in an alkaline solution for 60 s at 55 ° C. It was then rinsed with cold water for 30 s and rinsed with demineralized water for 10 s. The subsequent drying was carried out by blowing off with compressed air.
• the sheets pretreated in this way were then coated with a PUR paint from Weilburger Lackfabrik.
• the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to a salt spray test in accordance with DIN 50021 for a period of 480 h.

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• 1986
  • 1986-09-18 DE DE19863631667 patent/DE3631667A1/de not_active Withdrawn
• 1987
  • 1987-09-11 AT AT87113304T patent/ATE56485T1/de active
  • 1987-09-11 EP EP87113304A patent/EP0261519B1/fr not_active Expired - Lifetime
  • 1987-09-11 DE DE8787113304T patent/DE3764917D1/de not_active Expired - Fee Related
  • 1987-09-17 BR BR8704790A patent/BR8704790A/pt unknown
  • 1987-09-17 US US07/097,781 patent/US4775427A/en not_active Expired - Fee Related
  • 1987-09-17 DK DK488987A patent/DK488987A/da not_active Application Discontinuation
  • 1987-09-17 NO NO873904A patent/NO873904L/no unknown
  • 1987-09-17 FI FI874059A patent/FI874059A/fi not_active IP Right Cessation
  • 1987-09-18 JP JP62236050A patent/JPS6386875A/ja active Pending

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