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
• • 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
• • 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
  • C23C22/368—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 magnesium cations

Definitions

• the present invention relates to an acid aqueous phosphatic solution and a phosphating process using same to obtain a phosphatic film covering metal surfaces, said film providing excellent corrosion protection and adhesion toward coatings, in particular the coatings obtained by electrocoating.
• the phosphating process carried out at low temperatures on metal surfaces based on iron, zinc, aluminium, and steel is capable of preventing white spots formation, a phenomenon constituting a problem deeply felt especially by the automobile industry.
• Said solutions generally contain phosphate ions, zinc and/or manganese and a component, if any, selected among nickel, cobalt, copper, magnesium, calcium, nitrite, nitrate, chlorate and fluoride.
• the metal supports used at present are based on iron, aluminium, zinc, and preferably zinc plated steels (galvanized or electroplated) which, after paint application, proved to be the most resistant to corrosion.
• the zinc layer efficiency in preventing corrosion phenomena as well as its good adhesiveness result from zinc being reactive with CO2 and atmospheric oxygen, which causes the formation of zinc hydroxycarbonate that quickly adheres to the metal surface and inhibits further corrosion phenomena.
• Zinc also provides cathodic protection to steel, acting as the anode and undergoing corrosion instead of steel.
• the phosphating mechanisms seem to be the following: on steel 2 Zn2+ + Fe2+ + 2 PO43 ⁇ ⁇ > Zn2Fe(PO4)2 ⁇ 4 H2O (phosphophyllite) on zinc 3 Zn2+ + 2 PO43 ⁇ ⁇ > Zn3(PO4)2 ⁇ 4 H2O (hopeite)
• Crystalline phosphating processes are always conducted in the presence of an accelerator, i.e. an oxidizer, generally inorganic and sometimes organic, meant for obtaining surface conversion in a shorter and industrially acceptable time.
• an accelerator i.e. an oxidizer, generally inorganic and sometimes organic, meant for obtaining surface conversion in a shorter and industrially acceptable time.
• the accelerator action is twofold: it depolarizes the metal surface by acting in particular in the high electronic density (microcathodic) areas, and at the same time oxidizes the metals dissolved in the microanodic attack area causing their precipitation as insoluble phosphatic salts.
• accelerators i.e. oxidizers, reducers, or mixtures thereof, are used at the present state of the art.
• the nitrite (preferably as a sodium salt) is - among external components - the most widely used accelerator in microcrystalline phosphating processes.
• nitrite reasonably results from its easy availability, low cost and high oxidizing power.
• nitrite and/or nitro derivatives meets with insurmountable ecological problems, which cannot be dealt with successfully in compliance with the regulations in force.
• this compound has major drawbacks from the technical and ecological points of view, being thermally unstable under the usual operating conditions. Said instability inevitably brings about the formation of nitrogen oxide, whose vapours - having general formula NO x -vented to the atmosphere are highly polluting and aggressive.
• nitrite tends to be converted to nitrate ions, which require a troublesome treatment in purification plants.
• the aforesaid problems as well as the serious hazard connected with nitrite industrial handling and storage (a toxic and comburent substance according to EC standards in force) involve high operating costs, with no certainty of operating in compliance with the regulations in force.
• the metal surfaces to be treated When fed to the phosphating bath, the metal surfaces to be treated, in particular the surfaces based on zinc, usually exhibit non-uniform residual oxidation areas. It follows that preferential polarities arise in the course of the phosphating process, which always includes a preliminary pickling stage, wherein the phosphoric acid generated by the phosphatic system produces superficial etching. Anodic corrosion develops locally in the acid medium, with formation of punctiform cavities characterized by a vacancy of surface layer zinc. In the surface areas where iron is exposed, a "galvanic cell" probably operates on iron and metal zinc, thus allowing zinc dissolution to continue. Consequently, zinc hydroxides and phosphates might precipitate in excessive amounts and accumulate at the cavity limits.
• Phosphated surfaces would thus exhibit small blackish cavities characterized by lateral whitish deposits, mainly consisting of zinc hydroxides and phosphates, which would form the typical swollen efflorescence (Guy Lorin, La phosphatation des metaux, 20-21, Edition Eyrolles, 1973).
• the only remedy for removing the white spots that form after the phosphating process is of mechanical type, e.g. sanding or rubbing with paper or cloth.
• Such a hand-performed operation clearly involves too high costs of labour to be commercially viable.
• European patent EP 228,151 discloses a phosphating bath containing zinc, PO4 ion, manganese, and fluoride ions, and provides for the use of various accelerators, such as nitrite and nitro derivatives, but not hydroxylamine. According to the inventors, the problem of white spots formation may be partially solved by reducing the concentration of chloride ions in the phosphatic solution and, obviously, also of chlorate ions which, by reduction, slowly give chlorides.
• British patent application GB 2,179,680 identifies the presence of chloride ions as one of the major causes for white spots formation and provides for a phosphating solution that can be applied to zinc plated metal surfaces as a film capable of reducing said phenomenon. This result would be attained - though not to a wholly satisfatory extent - by nullifying the effect of chlorides through proportional additions of fluorides.
• the aforesaid solution should contain fluorides at a F ⁇ /Cl ⁇ ratio at least of 8:1 by weight.
• the chloride ions concentration should be of 50 ppm max., preferably of 20 ppm max., and optionally pretreatments of the metal surface should be carried out with solutions having a chlorides content of 100 ppm max. Said limits may be hardly proposed to the industry: in fact, values of 20 or 50 ppm are often exceeded even only by the main water salinity and may be easily reached also in phosphating baths prepared with demineralized water, owing to the drag out of main water used for previous washings.
• European patent EP 0264151 looks for the solution of the problem of white spots in a metal surface pretreatment stage and provides for a rinse operation - prior to activation - with a solution containing a mixture of sodium silicates, borates and nitrites.
• European patent EP 0224190 discloses the use of an activating solution based on titanium phosphates, added with disodium tetraborate or other alkaline borates at a PO4/B4O7 ratio of 1 min. Addition of B4O7 reduces the formation of white spots, which thus occurs at widely separated intervals, but does not wholly eliminate the phenomenon. Moreover, as disclosed in said patent, a serious pollution problem is brought about by the high amounts of Na2B4O7.10 H2O required (4 to 8 g/l).
• an acid aqueous solution containing hydroxylamine phosphate in association with a cationic surfactant, in particular a quaternary ammonic surfactant allows the obtainment, within a time meeting industrial requirements, of phosphatic layers having good corrosion resistance and adhesion to a paint coating, without formation of white spots.
• the present invention relates to an acid aqueous phosphating solution containing hydroxylamine phosphate and a cationic surfactant, preferably a quaternary ammonic surfactant, at given concentrations and ratios. More precisely, the present invention relates to phosphating solutions containing 0.6 to 3.0 g/l hydroxylamine phosphate and 0.001 to 1 g/l of cationic surfactant, preferably 0.005 to 0.1 g/l.
• the hydroxylamine phosphate/cationic surfactant ratio may range from 0.6 to 1000 by weight, preferably from 10 to 200.
• the solution may also contain 0.003 to 0.08 g/l of copper ions; 0.05 to 0.3 g/l of at least a polyfunctional sequestering agent selected from the group consisting of aminated polyacid complexing agents acting as accelerators, such as EDTA, and organic polyacids, such as tartaric and citric acids, and preferably EDTA and/or tartaric acid at a concentration of 0,08 to 0,1 g/l; an amount of non-ionic emulsifier, acting as defoaming agent, comoatible with the phosphating process and the usual passivation and electrocoating treatments, ranging from 10 to 30% by weight of the cationic surfactant content.
• a polyfunctional sequestering agent selected from the group consisting of aminated polyacid complexing agents acting as accelerators, such as EDTA, and organic polyacids, such as tartaric and citric acids, and preferably EDTA and/or tartaric acid at a concentration of 0,08 to 0,1
• compositions according to the present invention conveniently contain:
• said amount of nickel ions may be substituted by a combination of magnesium and cobalt ions, wherein magnesium ions range from 0.5 to 1.5 g/l and cobalt ions range from 0.05 to 0.2 g/l.
• Particularly suitable cationic surfactants are the ammonic ones selected from the groups consisting of:
• n ranges from 10 to 12
• m is 1 or 2
• R1, R2, R3 H and/or methyl, with R being C12-C14 alkyl, which prove to be highly effective for white spots removal.
• the cationic surfactants may suitably form even in situ in the phosphating solution, by adding to the phosphating bath a surfactant of formula: wherein R and n have the above meaning.
• the copper ion contained in the claimed solution contributes to the improvement in quality of the phosphatic layer, which becomes more conductive.
• Said advantageous use of copper ions is made possible by the presence of the hydroxylamine phosphate/cationic surfactant system which, in any case, hinders the formation of white spots. In the absence of said system, copper ions cause white spots formation already at concentrations of 0.003 to 0.005 g/l.
• the phosphatic solution according to the present invention exhibits a total acidity value ranging from 10 to 28 points, a free acidity value ranging from 0.5 to 2.0 points, at an acid ratio (i.e. total acidity/free acidity ratio) of 5 to 56.
• acidity values phosphatic films may be obtained at a low cost and the metal surface does not undergo pronounced corrosion.
• the total acidity value refers to the number of millilitres of 0.1 N NaOH necessary to titrate 10 ml of the claimed phosphatic solution using phenolphthalein as indicator and the free acidity value refers to the number of millilitres of 0.1 N NaOH necessary to titrate 10 ml of the claimed phosphatic solution using methyl yellow as indicator.
• the phosphating process according to the present invention may be conducted by spraying or immersion or a combination thereof, for a period of 1 to 5 min., at a temperature of 40°C to 55°C. At temperatures below said range, acceptable layers could be obtained only after long processing times, whereas at temperatures above said range, the phosphating accelerator would decompose more quickly, which would unbalance the solution components concentrations and make it difficult to obtain satisfactory phosphatic films.
• microcrystalline phosphate layer obtained on the basis of the procedure of the present invention weighs 1.5 to 5.0 g/m2.
• the claimed process carried out either by spraying or by immersion, reduces white spots formation of 98%.
• the phosphatic film can be satisfactorily applied also to complex-shaped articles, such as automobile bodies.
• the phosphating process based on immersion according to the present invention is carried out at a temperature preferably ranging from 45°C to 50°C, for a period of 2 to 5 min.
• the acid aqueous phosphatic solution used in said treatment preferably contains 13 to 15 g/l phosphate ions, 1.0 to 1.5 g/l zinc ions, 2.5 to 3.5 nitrate ions, 0.6 to 1.1 g/l manganese ions, 0.001 to 0.05 g/l iron ions, 0.4 to 0.6 g/l nickel ions, 0.6 to 0.8 g/l fluoride ions, 1 to 2 g/l hydroxylamine phosphate and 0.01 to 0.1 g/l cationic surfactant.
• the solution may also contain 0.003 to 0.006 g/l copper ions and 0.05 to 0.3 g/l organic polyfunctional sequestering agent, preferably EDTA and/or tartaric acid.
• the total acidity value preferably ranges from 18 to 22 points and the free acidity value from 1 to 2 points.
• the phosphating process based on spraying according to the present invention is carried out at a temperature preferably ranging from 45°C to 50°C, for a period of 1 to 3 min., under a spraying-pressure of 1 to 2.5 atm.
• the acid aqueous phosphatic solution used in said treatment preferably contains 9.0 to 11.2 g/l phosphate ions, 0.8 to 1.2 g/l zinc ions, 1.7 to 3.0 nitrate ions, 0.4 to 0.7 g/l manganese ions, 0.001 to 0.04 g/l iron ions, 0.4 to 0.5 g/l nickel ions, 0.4 to 0.7 g/l fluoride ions, 0.8 to 1.6 g/l hydroxylamine phosphate and 0.01 to 0.1 g/l cationic surfactant.
• the solution may also contain 0.003 to 0.006 g/l copper ions and 0.05 to 0.3 g/l organic polyfunctional sequestering agent, preferably EDTA and/or tartaric acid.
• the total acidity value preferably ranges from 13 to 14 points and the free acidity value from 0.6 to 0.8 points.
• Said procedure by spraying yields microcrystalline phosphatic layers weighing 1 to 3.5 g/m2 on iron substrates, and 1.5 to 3.5 g/m2 on sheet iron zinc plated electrolytically.
• immersion and immersion/spraying treatments are preferred to spraying and spraying/immersion treatments.
• a treatment combining spraying with immersion may consist of immersion at 45°C to 50°C, for a period of 100 to 200 sec., followed by spraying at 45°C to 50°C, for a period of 20 to 50 sec., or of spraying at 45°C to 50°C, for a period of 20 to 50 sec., followed by immersion at 45°C to 50°C, for a period of 100 to 200 sec.
• the treatment based on immersion followed by spraying is particularly suitable for complex-shaped articles, such as automobile bodies.
• the constituents of the acid aqueous phosphatic solution of the present invention may be obtained from the following compounds:
• the solutions may be modified or added with alkaline metal hydroxides, ammonium hydroxide, and preferably sodium hydroxide.
• the metal surfaces to be treated according to the present invention include surfaces based on iron, zinc, aluminium and/or their respective alloys. Said metal surfaces may be treated either singly or in combination.
• the new process is particularly advantageous for articles consisting of zinc- and iron-based surfaces, as is the case of automobile bodies.
• Examples of zinc-based surfaces are zinc plated sheet steel, skimmed sheet steel, sheet steel zinc plated by electrodeposition, sheet steel zinc-alloy plated by electrodeposition, and complex sheet steel zinc plated by electrodeposition.
• the acid aqueous phosphatic solutions of the present invention may be conveniently prepared by diluting an aqueous concentrate containing the solution constituents at the right ratios by weight and adding some elements, as required, e.g. pH adjusting agents or accelerators.
• the process of the invention includes advantageous pretreatments of the metal surfaces, i.e. degreasing with weakly or strongly alkaline degreasers or with acid degreasers, followed and/or preceded by one rinse with water.
• the metal surfaces may be then subjected to conditioning with a titanium or zirconium solution.
• Particularly suitable for the purpose is a solution containing 0.0003% to 0.05%, preferably 0.0005% to 0.001%, titanium on phosphatic support.
• a dilute chromic solution containing, e.g., 0.025% to 0.1% chromium in the form of chromium (III) or chromium (VI) or a mixture thereof.
• metal salts such as aluminium, zirconium, etc.
• the surfaces exhibit a good resistance to corrosion and a good adhesion to the paint layer later applied by cathode-type electrocoating, since no white spots formation occurred.
• Tests were conducted on steely sheets, zinc plated on both sides (with an 8 to 10 ⁇ m thick zinc layer) by electrodeposition, i.e. by electrolytic zinc plating.
• the said sheets were treated according to the following operating cycle:
• the degreasing solution used consisted of: Disodium phosphate ca. 7 g/l Sodium metasilicate.5 H2O ca. 7 g/l Trisodium phosphate.12 H2O ca. 3 g/l Neutral sodium pyrophosphate ca. 1.8 g/l Non-ionic surfactants ca. 1 g/l Hydrotropes ca. 1 g/l
• the treatment was carried out by immersion at a temperature of 55°C to 60°C, for a period of 3 to 5 minutes.
• the activating solution used consisted of: Titanium 5 to 6 mg/l PO4 150 to 200 mg/l P3O10 450 to 500 mg/l
• the treatment was carried out by immersion at a temperature of 20°C, for a period of 1 minute.
• Phosphating was carried out by immersion at a temperature of 50°C, for a period of 3 minutes, using standard 5 l vessels constructed of antiacid material, heated electrically to the desired temperature, and maintained under magnetic stirring.
• the three different phosphating solutions used consisted of: PO4 ions ca. 13 to 15 g/l Zinc ions ca. 1 to 1.2 g/l NO3 ions ca. 3 to 3.5 g/l Manganese ions ca. 1 to 1.2 g/l Nickel ions ca. 0.4 to 0.5 g/l Iron ions ca. 0.005 to 0.02 g/l Total fluoride ions ca. 660 to 715 mg/l Total acidity value 18 points Free acidity value 1.8 points
• White spots may be seen with the naked eye, but preferably through an optical microscope, being 0.5-1.5 mm microdome-shaped punctiform white efflorescences, which show up on the grey surface of a phosphated sheet zinc plated by electrodeposition.
• Tests were conducted on steely sheets (FePO4), zinc plated on both sides (with an 8 to 10 ⁇ m thick zinc layer) by electrodeposition, i.e. by electrolytic zinc plating. Degreasing and activating stages were as described in Example 1.
• Phosphating was carried out by immersion at a temperature of 50°C, for a period of 3 minutes, using standard 5 l vessels constructed of antiacid material, heated electrically to the desired temperature, and maintained under magnetic stirring.
• a phosphating bath as per Example 1 was added with hydroxylamine phosphate (2 g/l) and chloride ions (100 ppm; 0.1 g/l).
• the phosphating solution used consisted of: PO4 ions ca. 13 to 15 g/l Zinc ions ca. 1 to 1.2 g/l NO3 ions ca. 3 to 3.5 g/l Manganese ions ca. 1 to 1.2 g/l Nickel ions ca. 0.4 to 0.5 g/l Iron ions ca. 0.005 to 0.02 g/l Total fluoride ions ca. 660 to 715 mg/l Total acidity value 18 points Free acidity value 1.5 points
• Tests were conducted on ferrous sheets zinc plated on both sides by electrodeposition, i.e. by electrolytic zinc plating.
• Phosphating was carried out by immersion at a temperature of 50°C, for a period of 3 minutes, using standard 5 l vessels constructed of antiacid material, heated electrically to the desired temperature, and maintained under magnetic stirring.
• the phosphating solution used consisted of: PO4 ions ca. 13 to 15 g/l Zinc ions ca. 1 to 1.2 g/l NO3 ions ca. 3 to 3.5 g/l Manganese ions ca. 1 to 1.2 g/l Nickel ions ca. 0.4 to 0.5 g/l Iron ions ca. 0.005 to 0.02 g/l Total fluoride ions ca. 660 to 715 mg/l Hydroxylamine phosphate ca. 2 g/l Total acidity value 18 points Free acidity value 1.5 points
• solutions containing the aforesaid amounts of chloride and increasing amounts of the cationic surfactant of the invention, i. e. 30 ppm (solution A'), 60 ppm (solution B') and 90 ppm (solution C'), were prepared. Solutions A', B', and C' were also added with a defoaming agent.
• the degreasing solution used consisted of: Disodium phosphate ca. 7 g/l Sodium metasilicate ⁇ 5 H2O ca. 7 g/l Trisodium phosphate ⁇ 12 H2O ca. 3 g/l Neutral sodium pyrophosphate ca. 1.8 g/l Non-ionic surfactants ca. 1 g/l Hydrotropes ca. 1 g/l
• the treatment was carried out by immersion at a temperature of 50°C to 60°C, for a period of 2 to 5 minutes.
• the rinse was carried out using common water at room temperature.
• the activating solution used consisted of: Titanium 8 to 9 mg/l PO4 130 to 150 mg/l P2O7 350 to 400 mg/l
• the treatment was carried out by immersion at a temperature of 20°C to 40°C, for a period of 30 sec. to 120 sec.
• Phosphating stage was carried out, both by spraying treatment (A) and by immersion/spraying treatment (B).
• A) Phosphating by spraying treatment was carried out at a temperature of about 50°C, for a period of 180 sec.
• the phosphating solution used consisted of: Hydroxylamine phosphate 1.3 g/l cationic surfactant of formula (I)* 0.02 g/l PO4 ions 21 g/l Zinc ions 0.6 g/l NO3 ions 3 g/l Manganese ions 1 g/l Magnesium ions 1 g/l Cobalt ions 0.1 g/l Iron ions 0.01 g/l Total fluoride ions 780 mg/l Total acidity value 24.5 points Free acidity value 1.0 points *
• the rinse was carried out using common water at room temperature.
• the treatment was carried out by immersion at a temperature of 20 to 40°C, for a period of 30 to 120 sec., in a passivating solution consisting of: H2Cr2O7 0.15 g/l Cr(NO3)3 0.20 g/l
• the rinse was carried out at room temperature, for a period of 10 to 60 sec., by immersion in demineralized water.
• the sheets after the above mentioned operating cycle, underwent a three-coats painting according to a typical automobile treatment (cathodic-epoxidic primer, epoxidic undercoat and alkyd-enamel topcoat), obtaining a total thickness of 95 to 105 ⁇ m, and were subsequently subjected to corrosion and adhesion tests, as reported hereinbelow.
• the coated sheets painted as above, underwent Scab Corrosion Test according to FIAT standard 500412 (test method 50493/02), relating to the resistance of coatings to corrosion, after chipping damage by stones and other flying objects, and after incisions through the film to the substrate.
• the coated test panels were preliminary submitted to a conditioning stage, by immersion in demineralized water, at 38°C for 120 hours, followed by protection of the panels edges with adhesive tape or wax. At least an hour after said pre-treatment, standardized road gravel was projected by means of a controlled air blast at half part of the coated specimens in a gravellometer, while on the remaining half parts of the specimens an incision was made through the film to the substrate, with an angle of 45 deg. to the edges of the specimens.
• the panels were exposed to atmospheric agents, being protected against the rain, and they were salt sprayed with a solution of NaCl 5% twice a week.
• the resultant chipping effects were evaluated by comparison with a set of reference photographs; 1D indicates more than 250 chips on a surface of more than 6 mm diameter, 3C indicates 100-150 chips on a surface of 3-6 mm diameter, 5B indicates 50-74 chips on a surface of 1-3 mm diameter and 7A indicates 10-24 chips on a surface of less than 1 mm diameter.
• the degreasing solution used consisted of: Disodium phosphate ca. 7 g/l Sodium metasilicate ⁇ 5 H2O ca. 7 g/l Trisodium phosphate ⁇ 12 H2O ca. 3 g/l Neutral sodium pyrophosphate ca. 1.8 g/l Non-ionic surfactants ca. 1 g/l Hydrotropes ca. 1 g/l
• the treatment was carried out by immersion at a temperature of 50°C, for a period of 3 minutes.
• the rinse was carried out using common water at room temperature, for a period of 1 minute.
• the activating solution used consisted of: Titanium 8 to 9 mg/l PO4 130 to 150 mg/l P2O7 350 to 400 mg/l
• the treatment was carried out by immersion at a temperature of 20°C, for a period of 1 minute.
• Phosphating stage was carried out by immersion at a temperature of 50°C, for a period of 3 minutes, using standard vessels constructed of antiacid material, heated electrically to the desired temperature, and mantained under magnetic stirring.
• the phosphating solutions used were as follows: PO4 ions ca. 13 to 15 g/l Zinc ions ca. 1 to 1.2 g/l NO3 ions ca. 3 to 3.5 g/l Manganese ions ca. 1 to 1.2 g/l Nickel ions ca. 0.4 to 0.5 g/l Iron ions ca. 0.005 to 0.02 g/l Total fluoride ions ca. 660 to 715 mg/l Hydroxylamine phosphate ca. 2 g/l Total acidity value 24 points Free acidity value 1.6 points
• the rinse was carried out by immersion in common water at room temperature, for 1 minute, and then in demineralized water at room temperature, for 3 minutes.
• the passivation stage was not performed in order to render more severe the comparison of the results obtained using the aforesaid phosphatic solutions, in the presence or in the absence of the cationic surfactant of the invention.
• the sheets underwent the above mentioned operating cycles, yelding microcrystalline phosphate layers of even appearance.
• coated sheets painted as above, underwent a corrosion test according to ASTM B 117.
• coated sheets painted as above, underwent Scab Corrosion Test according to FIAT standard 500412 (test method 50493/02), as described in Example 5.

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• 1994
  • 1994-08-05 IT ITMI941715A patent/IT1274594B/it active IP Right Grant
• 1995
  • 1995-08-01 EP EP95112068A patent/EP0695817A1/fr not_active Withdrawn
  • 1995-08-04 CA CA002155484A patent/CA2155484A1/fr not_active Abandoned
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