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
  • C23C22/34—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
• • 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
  • C23C22/37—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 hexavalent chromium compounds

Definitions

• This invention relates to processes of treating metal surfaces with aqueous acid ⁇ ic compositions to increase the resistance to corrosion of the treated metal surface, ei- ther as thus treated or after subsequent overcoating with some conventional organic based protective layer.
• a major object of the invention is to provide a storage stable, preferably single package, treatment that can be substantially free from hexavalent chromium but can protect metals substantially as well as the hexavalent chromium containing treatments of the prior art, or can improve the stability of treatment solu- tions that do contain hexavalent chromium.
• This invention also relates to reaction of fluorometallic acids with other metal or metalloid containing materials to produce compositions or intermediates for compositions useful for such treatments.
• percent, "parts of, and ratio values are by weight;
• the term "polymer” includes oligomer;
• the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred;
• descrip ⁇ tion of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed;
• specification of materials in ionic form implies the presence of sufficient counterions to produce electrical neutrality for the composition as a whole (any counterions thus implicitly specified should preferably be selected from among other constituents explicitly spec ⁇ ified in ionic form, to the extent possible; otherwise such counterions may be freely selected, except for avoiding counterions that act adversely to the stated objects of the invention); and the term "mole” and its variations may be applied to elemental, ionic, and any other chemical species defined by number and type
• aqueous compositions comprising (A) a component of dissolved fluoroacids of one or more metals and metalloid elements selected from the group of elements consisting of titanium, zirconium, hafnium, boron, aluminum, sil ⁇ icon, germanium, and tin and, (B) a component of one or more of (i) dissolved or dis ⁇ persed finely divided forms of metals and metalloid elements selected from the group of elements consisting of titanium, zirconium, hafnium, boron, aluminum, silicon, ger ⁇ manium, and tin and (ii) the oxides, hydroxides, and carbonates of such metals and metalloid elements can be caused to chemically interact in such a manner as to pro ⁇ quiz a composition useful for novel metal treatments.
• component (B) is present in dispersion rather than solution, as is generally preferred, the initial composition nor- mally will not be optically transparent, because of the scattering of visible light, in a thickness of 1 centimeter ("cm"), and the occurrence of the desired chemical interac ⁇ tion can be determined by the clarification of the composition. If components (A) and (B) as defined above are both present in the precursor aqueous composition in suffi ⁇ ciently high concentrations, adequate chemical interaction between them may occur at normal ambient temperatures (i.e., 20 - 25 ° C) within a practical reaction time of
• component (B) is dissolved or dispersed in very finely divided form.
• Mechanical agitation may be useful in speeding the desired chemical interaction and if so is preferably used. Heating, even to relatively low temperatures such as 30° C, is often useful in speeding the desired chemical interaction, and if so is also preferred.
• the desired chemical interaction between components (A) and (B) of the mixed composition eliminates or at least markedly reduces any tendency toward settling of a dispersed phase that might otherwise occur upon long term storage of the initial mixture of components (A) and (B) as defined above.
• another component (D) made up of water soluble oxides, carbon ⁇ ates, or hydroxides of at least one of Ti, Zr, Hf, B, Al, Si, Ge, and Sn may also be added before, after, or simultaneously with component (C) but after the interaction of components (A) and (B).
• water soluble means a solubility to at least 1 % in water at normal ambient temperature, and “water insoluble” means less soluble than this.
• compositions are suitable for treating metal surfaces to achieve excellent resistance to corrosion, particularly after subsequent conventional coating with an organic binder containing protective coating.
• the compositions are particu ⁇ larly useful on iron and steel, galvanized iron and steel, zinc and those of its alloys that contain at least 50 atomic percent zinc, and, most preferably, aluminum and its alloys that contain at least 50 atomic percent aluminum.
• the treating may consist ei ⁇ ther of coating the metal with a liquid film of the composition and then drying this liquid film in place on the surface of the metal, or simply contacting the metal with the composition for a sufficient time to produce an improvement in the resistance of the surface to corrosion, and subsequently rinsing before drying. Such contact may be achieved by spraying, immersion, and the like as known per se in the art.
• the invention also provides a process for effectively coating the above-stated metallic surfaces in the absence of an intermediate rinsing step.
• the process comprises the steps of (i) cleaning the metal surface to be coated, (ii) rinsing the cleaned metal surface with water so as to remove any excess cleaning solution, (iii) contacting the metallic surface with the above-described coating composition, and (iv) drying the coated metallic surface.
• compositions and process for coating surfaces of aluminum and alloys thereof wherein the composition comprises, preferably consists essentially of, or more preferably consists of, water and a mixture of: (A') a water soluble or dispersible polymer having at least one alcohol functionality selected from the group consisting of polyvinyl alcohol, polyethylene glycol, modified starch, and mixtures thereof and (B') polymers and copolymers of acrylic and methacrylic acid and their salts, and, optionally, one or more of the following: a component (C) selected from the group consisting of the same fluorometallic acids, with the same preferences, as recited for component (A) herein; a component (D') of metallic and/or metalloid elements and their oxides, hydroxides, and/or carbonates, with the same preferences, as recited for component (B) herein; and a component (E') selected from the group consisting of water soluble oxides, carbonates, or hydroxides of at
• compositions above do not pre ⁇ clude the possibility of unspecified chemical interactions among the components listed, but instead describes the components of a composition according to the invention in the form in which they are generally used as ingredients to prepare such a composi ⁇ tion.
• a chemical interaction most probably to produce oxyfluro complexes of the metal or metalloid elements or their compounds heated in contact with fluorometallic acids, is believed to occur, but the invention is not limited by any such theory.
• the fluoroacid component (A) to be caused to interact in a mixture with one or more metals and/or metalloid ele ⁇ ments and/or oxides, hydroxides, and/or carbonates thereof in a process according to one embodiment of the invention may be freely selected from the group consisting of H 2 TiF 6 , H 2 ZrF 6 , H 2 HfF 6 , H 3 A1F 6 , H 2 SiF 6 , H 2 GeF 6 , H 2 SnF 6 , HBF 4 , and mixtures thereof.
• H 2 TiF 6 , H 2 ZrF 6 , H 2 HfF 6 , H 2 SiF 6 , HBF 4 , and mixtures thereof are preferred; H 2 TiF 6 , H 2 ZrF 6 , H 2 SiF 6 and mixtures thereof are more preferred; and H 2 TiF 6 is most preferred.
• concentration of fluoroacid component at the time of interaction is preferably be ⁇ tween 0.01 and 7 moles per liter (hereinafter "M"), more preferably between 0.1 and 6 .
• the component (B) of metallic and/or metalloid elements and/or their oxides, hydroxides, and/or carbonates is preferably selected from the group consisting of the oxides, hydroxides, and/or carbonates of silicon, zirconium, and/or aluminum and more preferably includes silica.
• Any form of this component that is sufficiently finely di- vided to be readily dispersed in water may be used in a process according to one em ⁇ bodiment of this invention, but for constituents of this component that have low sol ⁇ ubility in water it is preferred that the constituent be amorphous rather than crystalline, because crystalline constituents can require a much longer period of heating and/or a higher temperature of heating to produce a composition that is no longer susceptible to settling and optically transparent.
• Solutions and/or sols such as silicic acid sols may be used, but it is highly preferable that they be substantially free from alkali metal ions as described further below. However, it is generally most preferred to use dispersions of silica made by pyrogenic processes.
• An equivalent of a metallic or metalloid element or of its oxide, hydroxide, or carbonate is defined for the purposes of this description as the amount of the material containing a total of Avogadro's Number (i.e., 6.02xl0 23 ) of atoms of metal and or metalloid elements from the group consisting of Ti, Zr, Hf, B, Al, Si, Ge, and Sn.
• the ratio of moles of fluoroacid component (A) to total equivalents of component (B) in an aqueous composition heated according to one embodiment of this invention preferably is from 1:1 to 50:1, more preferably from 1.5:1.0 to 20:1, or still more preferably from 1.5:1 to 5.0:1.0.
• a constituent of this component may be treated on its surface with a silane coupling agent or the like which makes the surface oleophilic.
• an aqueous liquid composition comprising, preferably consisting essentially of, or more preferably consisting of, water and components (A) and (B) as described above, which composition scatters vis- ible light, is not optically transparent in a thickness of 1 cm, and/or undergoes visually detectable settling of a solid phase if maintained for at least 100 hours at a tempera ⁇ ture between its freezing point and 20° C, is maintained at a temperature of at least 21° C, optionally with mechanical agitation, for a sufficient time to produce a compo ⁇ sition that (i) does not suffer any visually detectable settling when stored for a period of 100, or more preferably 1000, hours and (ii) is optically transparent in a thickness of 1 cm.
• the temperature at which the initial mixture of components (A) and (B) is maintained is in the range from 25 to 100 ° C, or more preferably within the range from 30 to 80 ° C, and the time that the composition is maintained within the stated temperature range is within the range from 3 to 480, more preferably from 5 to 90, or still more preferably from 10 to 30, minutes (hereinafter often abbreviated
• shorter times and lower temperatures within these ranges are generally ade ⁇ quate for converting compositions in which the component (B) is selected only from dissolved species and/or dispersed amorphous species without any surface treatment to reduce their hydrophilicity, while longer times and/or higher temperatures within these ranges are likely to be needed if component (B) includes dispersed solid crystal ⁇ line materials and/or solids with surfaces treated to reduce their hydrophilicity.
• component (B) includes dispersed solid crystal ⁇ line materials and/or solids with surfaces treated to reduce their hydrophilicity.
• the pH of the aqueous liquid composition combining components (A) and (B) as described above be kept in the range from 0 to 4, more preferably in the range from 0.0 to 2.0, or still more preferably in the range from 0.0 to 1.0 before beginning maintenance at a temperature of at least 21° C as de ⁇ scribed above.
• a composition made as described immediately above is suitable for use as a protective treatment for metals.
• a better protective treatment composition may be obtained by mixing the product of interaction between compon- ents (A) and (B) as described above with a third component (C) as also noted above.
• compositions including component (C) after maintenance of a composi ⁇ tion containing components (A) and (B) as described above at a temperature and for a time sufficient to promote their interaction, the composition is preferably brought if necessary to a temperature below 30° C and then mixed with a component consist- ing of at least one of (i) at least one water soluble or dispersible polymer and/or co ⁇ polymer, preferably selected from the group consisting of (i.l) polyhydroxyl alkyla- mino derivatives of poly ⁇ p-hydroxystyrene ⁇ as described above and, in more detail, in U. S.
• Suitable and preferred water soluble polymers and methods of preparing them are de ⁇ scribed in detail in U. S. Patent 4,963,596.
• the ratio by weight of the sol ⁇ ids content of component (C) to the total of active ingredients of component (A) as described above is in the range from 0.1 to 3, more preferably from 0.2 to 2, or still more preferably from 0.20 to 1.6.
• compositions prepared by a process as described above constitutes another embodiment of this invention. It is normally preferred that compositions according to the invention as defined above should be substantially free from many ingredients used in compositions for similar purposes in the prior art. Specifically, it is often in ⁇ creasingly preferred in the order given, independently for each preferably mii-imized component listed below, that these compositions, when directly contacted with metal in a process according to this invention, contain no more than 1.0, 0.35, 0.10, 0.08,
• hexavalent chromium hexavalent chromium
• ferricyanide ferrocyanide
• anions containing molybdenum or tungsten ni ⁇ trates and other oxidizing agents (the others being measured as their oxidizing sto- ichiometric equivalent as nitrate); phosphorus and sulfur containing anions that are not oxidizing agents; alkali metal and ammonium cations; and organic compounds with two or more hydroxyl groups per molecule and a molecular weight of less than 300.
• compositions used for processes according to the invention that include drying into place on the metal surface to be treated without rinsing after contact between the metal surface and the composition containing at least components (A) and (B) as de ⁇ scribed above; when a composition according to the invention is contacted with a metal surface and the metal surface is subsequently rinsed with water before being dried, any alkali metal and ammonium ions present are usually removed by the rinsing to a sufficient degree to avoid any substantial cli ⁇ iinution of the protective value of subsequently applied organic binder containing protective coatings.
• the prefer ⁇ ence for minimization of the amount of hexavalent chromium present is due to the polluting effect of hexavalent chromium, and where there is an absence of legal restraints against pollution and/or sufficiently economical means of disposing of the hexavalent chromium without environmental damage exist, this preference does not apply.
• hexavalent chromium may advantageously be incorporated into working compositions according to this invention themselves, and in another specialized embodiment of the invention, liquid compositions containing hexavalent chromium may be used as posttreatments after application of a coating according to this invention but before final overcoating with a paint or the like, in order further to improve corrosion resistance of the metal surface treated.
• the other major type of coating used in the invention employing a coating composition including necessary components (A') and (B') as already described above, has been found to be especially useful for treating metallic surfaces that are exposed to alkali metal ions, particularly sodium such as often occurs in detergents and other cleaners, after the treatment with a composition according to this invention has been completed.
• a coating composition including necessary components (A') and (B') as already described above, has been found to be especially useful for treating metallic surfaces that are exposed to alkali metal ions, particularly sodium such as often occurs in detergents and other cleaners, after the treatment with a composition according to this invention has been completed.
• Protective coatings applied to metallic surfaces, particularly aluminum preferably are water insoluble and inhibit corrosion.
• metallic surfaces bear ⁇ ing a protective coating are often exposed to sodium ions later.
• the composition contacted with a metallic surface comprises water and: (A') from 0.5 to 50 g/1 and (B') from 0.5 to 50, and more preferably from
• polyvinyl alcohol used in the invention preferably is a low molecular weight polyvinyl alcohol which is 75 - 99+ mole % hydrolyzed, and has an average degree of polymerization ranging from 100 - 600.
• water soluble or dispersible polymer having at least one -OH group per polymer molecule may be employed without departing from the spirit of the in ⁇ vention
• preferred polymers and amounts thereof include the above-stated polyvinyl alcohol; from 0.3 to 16 g/1, preferably from 0.3 to 1.2 g/1, of polyethylene glycol having a molecular weight of from 90,000 to 900,000; from 0.5 to 16 g/1, and prefer ⁇ ably from 0.5 to 10 g/1 of dextrin, cyclodextrin, or a modified starch.
• modified starch is one commonly known in the art.
• starch refers to any of several water-soluble polymers derived from a starch by acetylation, chlorination, acid hydrolysis, or enzymatic action. These reactions yield starch acetates, esters, and ethers in the form of staible and fluid solutions and films. These starch derivatives useful herein are well known.
• the hydroxyalkyl starch ethers and starch esters can be obtained by known etherification and esterification processes. These starch ethers and esters should have a degree of substitution (hereinafter often abbreviated "D.S.") of 0.01 to 0.5, and preferably 0.1 to 0.5. As used herein D.S. means the average degree of substitution of starch hydroxyl groups per anhydroglucose unit of the chemical modifying substitu ⁇ ent, as for example a hydroxalkyl or carbonyl group.
• D.S. degree of substitution of starch hydroxyl groups per anhydroglucose unit of the chemical modifying substitu ⁇ ent, as for example a hydroxalkyl or carbonyl group.
• Oxidized starch can be obtained by known processes involving oxidation of starch with a suitable oxidizing agent, as for example sodium hypochlorite, potassium dichromate and sodium permanganate.
• a suitable oxidizing agent as for example sodium hypochlorite, potassium dichromate and sodium permanganate.
• the starch can be oxidized under acid, alkaline or neutral conditions, and the resulting product can contain carboxyl and carbonyl groups.
• the oxidized starch has a "D.O.” value of 0.01 to 1.0, where "D.O.” refers to the number of carboxyl groups introduced per anhydroglucose unit.
• Dextrins and cyclodextrins are polysaccharide products of a complex nature re ⁇ sulting from the partial degradation of starch, such as corn starch, potato starch, wheat starch, and the like, with heat, as for example, by roasting with acid or alkaline cata ⁇ lysts.
• Linear and branched dextrins are classified in three types. The particular type obtained depends on the heating time, temperature, and catalyst employed in the treat ⁇ ment of the starch. These types are classified as white dextrins, yellow or canary dex ⁇ trins, and British gums, and all such dextrins are suitable herein. White and canary dextrins are preferred in that British gums are brown in color.
• White dextrins are preferably pregelatinized (made water soluble during manufacture), if necessary, to render them more readily mixed with other water soluble components. Dextrins and methods for obtaining them are well known. See, for example, Whistler and Paschall op. cit., vol. I, p. 421 ff and vol. ⁇ , p. 253 ff.
• the starch hydrolysates useful in the compositions of this invention are a rela ⁇ tively new class of starch materials. These starch hydrolysates are made by subjecting a source of starch, such as hereinbefore mentioned, to enzyme or acid treatment or a combination of both.
• the starch hydrolysate should have a D.E. of from 2 to 35, and preferably have a D.E. of from 5 to 25. The most preferred materials have a D.E. within the range of 5 to 15.
• D.E. is used herein to refer to the reducing sugars content of the dissolved solids in a starch hydrolysate expressed as percent dextrose as measured by the Luff-Schoorl method [NBS Circular C-40, p. 195; also appearing in Polarimetry, Saccharimetry, and the Sugars published by Frederick J. Bates and Associates].
• modified starches include cyclodextrins, which are mac- rocyclic non-reducing D-glucosyl polymers containing six or more D-glucosyl residues bonded by ⁇ -(l,4) links.
• cyclodextrins can be found in Whistler and Paschall, op. cit, Vol. 1, pp. 209-224.
• the pH of a composition according to this invention that contains components (A') and (BO as necessary components preferably is in the range from 1.0 to 5.0, and more preferably from 1.0 to 3.5.
• the treating composition also includes from 0.2 to 19.0, and more preferably from 0.2 to 8.0 g/1, of fluoroacids component (CO admixed therein.
• Component (CO is preferably selected from the group consisting of H 2 TiF 6 , HjZrF ⁇ , and H 2 SiF 6 , and more preferably is H 2 TiF 6 or H ⁇ Fe-
• Still another embodiment of the invention is a process of treating a metal with a composition prepared as described above.
• the aqueous composition as described above be applied to the metal surface and dried in place thereon.
• coating the metal with a liquid film may be accomplished by immersing the surface in a container of the liquid compo ⁇ sition, spraying the composition on the surface, coating the surface by passing it between upper and lower rollers with the lower roller immersed in a container of the liquid composition, and the like, or by a mixture of methods.
• Excessive amounts of the liquid composition that might otherwise remain on the surface prior to drying may be removed before drying by any convenient method, such as drainage under the influ ⁇ ence of gravity, squeegees, passing between rolls, and the like.
• the surface to be coated is a continuous flat sheet or coil and precisely con- trollable coating techniques such as gravure roll coaters are used, a relatively small volume per unit area of a concentrated composition may effectively be used for direct application.
• the coating equipment used does not readily permit precise coating at low coating add-on liquid volume levels, it is equally effective to use a more dilute acidic aqueous composition to apply a thicker liquid coating that contains the same amount of active ingredients.
• the total amount of active ingredients of components (A), (B), and (C) and described above dried into place on the surface to be treated fall into the range of from 1 to 500, more preferably from 5 to 300, still more preferably from 5 to 150, milligrams per square meter (hereinafter often abbreviated as "mg/m 2 ") of surface area treated.
• Drying may be accomplished by any convenient method, of which many are known per se in the art; examples are hot air and infrared radiative drying. Independ ⁇ ently, it is preferred that the maximum temperature of the metal reached during drying fall within the range from 30 to 200, more preferably from 30 to 150, still more pref- erably from 30 to 75, ° C. Also independently, it is often preferred that the drying be completed within a time ranging from 0.5 to 300, more preferably from 2 to 50, still more preferably from 2 to 10, seconds (hereinafter abbreviated "sec") after coating is completed.
• sec seconds
• the metal to be treat- ed preferably is contacted with a composition prepared as described above at a temper ⁇ ature within the range from 25 to 90, more preferably from 30 to 85, still more pref ⁇ erably from 30 to 60, ° C for a time ranging from 1 to 1800, more preferably from 1 to 300, still more preferably from 3 to 30, sec, and the metal surface thus treated is subsequently rinsed with water in one or more stages before being dried.
• at least one rinse after treatment with a composition according this inven ⁇ tion preferably is with deionized, distilled, or otherwise purified water.
• the maximum temperature of the metal reached during drying fall within the range from 30 to 200, more preferably from 30 to 150, or still more preferably from 30 to 75, ° C and that, independently, drying be completed within a time ranging from to 0.5 to 300, more preferably from 2 to 50, still more preferably from 2 to 10, sec after the last contact of the treated metal with a liquid before drying is completed.
• a process according to the invention as generally described in its essential fea ⁇ tures above may be, and usually preferably is, continued by coating the dried metal surface produced by the treatment as described above with a siccative coating or other protective coating, relatively thick as compared with the coating formed by the earlier stages of a process according to the invention as described above.
• Such protective coatings may generally, in connection with this invention, be selected and applied as known per se in the art. Surfaces thus coated have been found to have excellent re ⁇ sistance to subsequent corrosion, as illustrated in the examples below. Particularly preferred types of protective coatings for use in conjunction with this invention in- elude acrylic and polyester based paints, enamels, lacquers, and the like.
• hexavalent chromium may impart sufficient additional corrosion protection to the treated metal surfaces to justify the increased cost of using and lawfully disposing of it.
• the metal surface to be treated according to the invention is first cleaned of any contaminants, particularly organic cont-uninants and foreign metal fines and/or inclusions.
• cleaning may be accomplished by methods known to those skilled in the art and adapted to the particular type of metal substrate to be treated.
• the substrate is most preferably cleaned with a conventional hot alkaline cleaner, then rinsed with hot water, squeegeed, and dried.
• the surface to be treated most preferably is first contacted with either an aqueous alkaline cleaning solution in accordance with that disclosed in U.S. Patent No. 4,762,638, incorporated herein by reference, or an aqueous acidic cleaning solution as disclosed in U.S. Pat. No. 4,370,173, also incorporated herein by reference.
• a source of fluoride such as HF may also be employed to even further enhance the cleaning process.
• the alumin ⁇ um is then subjected to a water rinse, after which a composition in accordance with the present invention may then be coated onto the aluminum in accordance with the processes disclosed herein.
• Test pieces of Type 3105 aluminum were spray cleaned for 15 seconds at 54.4°
• the applied liquid composition according to the invention was flash dried in an infrared oven that pro- Jerusalem approximately 49° C peak metal temperature. Samples thus treated were subse ⁇ quently coated, according to the recommendations of the suppliers, with various com ⁇ dismissal paints as specified further below.
• T-Bend tests were according to American Society for Testing materials (herein ⁇ after "ASTM") Method D4145-83; Impact tests were according to ASTM Method D2794-84E1; Salt Spray tests were according to ASTM Method B-l 17-90 Standard;
• Acetic Acid Salt Spray tests were according to ASTM Method B-287-74 Standard; and Humidity tests were according to ASTM D2247-8 Standard.
• the Boiling water im ⁇ mersion test was performed as follows: A 2T bend and a reverse impact deformation were performed on the treated and painted panel. The panel was then immersed for 10 minutes in boiling water at normal atmospheric pressure, and areas of the panel most affected by the T-bend and reverse impact deformations were examined to deter ⁇ mine the percent of the paint film originally on these areas that had not been exfoliat- ed. The rating is reported as a number that is one tenth of the percentage of paint not exfoliated. Thus, the best possible rating is 10, indicating no exfoliation; a rating of 5 indicates 50 % exfoliation; etc.
• Example 3 278.8 parts of the 10 % solution of water soluble polymer as used in Example 1.
• Example 4 241.5 parts of the 10 % water soluble polymer solution as used in Example 1
• Example 4 56.4 parts of aqueous 60 % fluotitanic acid
• Example 5 218.1 parts of the 10 % water soluble polymer solution as used in Example 1
• Example 5 218.1 parts of the 10 % water soluble polymer solution as used in Example 1
• Example 5 218.1 parts of the 10 % water soluble polymer solution as used in Example 1
• Example 5 218.1 parts of the 10 % water soluble polymer solution as used in Example 1
• Example 5 218.1 parts of the 10 % water soluble polymer solution as used in Example 1
• Example 6 279.5 parts of the 10 % solution of water soluble polymer as used in Example 1
• Example 6 52.0 parts of aqueous 60 % fluotitanic acid
• Example 8 666.0 parts of deionized water
• RDX 68654TM also known as RK 95928TM epoxy resin dispersion commercially available from Rh ⁇ ne-Poulenc, containing 40 % solids of poly ⁇ mers of predominantly diglycidyl ethers of bisphenol-A, in which some of the epoxide groups have been converted to hydroxy groups and the polymer molecules are phosphate capped
• Example 4 the SiO 2 used was surface modified with a silane, and because of its hydrophobic nature, the mixture containing this form of silica was heated for 1.5 hours at 70° C to achieve transparency. The remaining steps of the process were the same as for Example 1.
• Example 7 the first three ingredients listed were mixed together and main ⁇ tained at 40 ⁇ 5 ° C for 20 - 30 minutes with stirring and then cooled.
• the CrO 3 was dissolved in about fifteen times its own weight of water, and to this solution was added a slurry of the corn starch in twenty-four times its own weight of water. The mixture was then maintained for 90 minutes with gentle stirring at 88 ⁇ 6 ° C to reduce part of the hexavalent chromium content to trivalent chromium. Finally, this mixture was cooled with stirring and then added to the previously pre ⁇ pared heated mixture of fluotitanic acid, silicon dioxide, and water. This composition is used in the manner known in the art for compositions containing hexavalent and tri ⁇ valent chromium and dispersed silica, but it is much more stable to storage without phase separation. Comparative Example 1
• Comparative Example 2 18.9 parts of aqueous 60 % fluotitanic acid
• Example 1 9 10 65 mg/m 2 e0-l s Vf9 asTi s0-l s
• Example 10 10 54 mg/m 2 e 0-l s e N 2 as Ti s N s N Vf 9
• Example 10 10 64 mg/m 2 e 0-2 s e 0-l s 3 as Ti s 0-2 s s N Vf 9
• Example 4 8 65 mg/m 2 e N e N as Ti s N s N Vf
• Example 5 10 10 22 mg/m 2 e N e N as Ti s N s N Vf 9
• Example 5 10 54 mg/m 2 e N e N s N s N Vf
• Example 6 10 10 22 mg/ ⁇ ? e o-r e N s N s N Vf 9
• Example 6 10 54 mg/m 2 e o-r e N s N s N Vf
• Example 8 9.8 10 12 mg/m 2 e N e N s o-r s N N
• Example 8 9.6 10 24 mg/m 2 e N e N s o-r s N N
• Example 9 10 10 11 mg/m 2 e N e N s o-r s o-r N
• Example 9 9.8 10 24 mg/m 2 e o-r e N s o-r s 0-1 N
• Example 10 9.8 9.8 17 mg/m 2 e o-r e N s o-r s N Vf
• Example 10 10 39 mg/m 2 e o-r e ⁇ 2 as Ti s o-r s ⁇ Vf 9
• Example 10 10 48 mg/m 2 e o-r e ⁇ 2 as Ti s o-r ⁇ ⁇ Vf 9
• Example 10 10 70 mg/m 2 e 0-2 s e ⁇ 2 as Ti s o-r ⁇ ⁇ Vf 9
• Example 10 10 87 mg/m 2 e ⁇ e o-r 2 as Ti s o-r ⁇ ⁇ Vf 9
• Example 10 10 29 mg/m 2 e 0-2" e ⁇ 3 as Ti ⁇ o-r s ⁇ Vf 9
• Example 10 10 42 mg/m 2 e o-r e ⁇ 3 as Ti s o-r s ⁇ Vf 9
• Example 10 10 57 mg/m 2 e 0-1 e ⁇
• Example 7 10 65 mg/m 2 e o-r e ⁇ 4 as Ti s o-r s ⁇ Vf 9
• Example 10 10 54 mg/m 2 e ⁇ e ⁇
• Example 2 The storage stability of the compositions according to all of the examples above except Example 2 was so good that no phase separation could be observed after at least 1500 hours of storage. For Example 2, some settling of a slight amount of ap ⁇ parent solid phase was observable after 150 hours. GROUP ⁇
• test pieces of Type 5352 or 5182 aluminum were spray cleaned for 10 seconds at 54.4° C with an aqueous cleaner containing 24 g/L of PARCO® Cleaner 305 (commercially available from the Parker+Amchem Division of Henkel Corp., Madison Heights, Michigan, USA).
• the panels were rinsed with hot water; then they were sprayed with the respective treatment solutions according to the invention, which were the same as those already described above with the same Example Number, except that they were further diluted with water to the concentration shown in the tables below, for 5 seconds; and then were rinsed successively with cold tap water and deionized water and dried, prior to painting.
• DOWFAXTM 2A1 is commercially available from Dow Chemical and is de ⁇ scribed by the supplier as 45 % active sodium dodecyl diphenyloxide disulfonate.
• the "Cross Hatch” test after this treatment was made in the same way as described above for steps 2 - 4 after “Ninety Minute Steam Exposure”.
• the "Reverse Impact” test was made as described in ASTM D2794-84E1 (for 20 inch pounds impact), then proceed ⁇ ing in the same way as described above for steps 3 - 4 after "Ninety Minute Steam Exposure”.
• the "Feathering” test was performed as follows: Using a utility knife, scribe a slightly curved " V" on the back side of the test panel.
• Example 1 % by 2.9 7.9 mg/m 2 10 10 0 .35 mm 1 weight as Ti
• Example 11 the treatment liquid in this final stage was simply deionized water with a conductivity of not more than 4.0 ⁇ Siemens/cm, while in Example 12 the treatment liquid in this final stage was obtained by mixing 35 ml of ParcoleneTM 95AT and 2.0 ml of ParcoleneTM 88B with 7 liters of deionized water and had a pH of 5.18 and a conductivity of 56 ⁇ Sie- mens/cm.
• Bottom ParcoleneTM products noted are commercially available from the Par- ker+Amchem Div.
• the working solution for Examples 11 and 12 was prepared by diluting 200 grams of the concentrate II-II, along with sufficient sodium carbonate to result in a pH of 2.92 ⁇ 0.2, to form 6 liters of working composition.
• the working solution was made in the same way, except that it also contained 5 grams of a concentrated polymer solution made according to the directions of column 11 lines 39
• a first concentrate was made by mixing 750 parts of tap water and 274 parts of AcrysolTM A-l, a commercially available product from Rohm and Haas containing 25 % solids of polymers of acrylic acid with a molecular weight of less than 50,000.
• a second concentrate was made by mixing, in a container separate from that used for the first concentrate 951.3 parts of tap water and 66.7 g/1 of GohsenolTM GLO-5, a commercially available product from Nippon Gohsei which is a low molecular weight polyvinyl alcohol; the latter was added to the tap water with stirring at a slow and controlled flow, after which the temperature was increased to 49 - 54 ° C for 30 min- utes with slow stirring until all was dissolved.
• This composition was then contacted with an aluminum surface by dipping or spraying for a time from 30 to 60 seconds, after which time the surfaces treated were removed from contact with the treating composition, allowed to dry in the ambient atmosphere without rinsing, and then baked in a warm air oven, at 88° C for 5 minutes to simulate commercial operating conditions.
• the surfaces thus prepared were painted with conventional paints. Examples 15 - 20
• the treating composition is prepared in the same general manner as in Example 14, by making separate concentrates of the hydroxyl group containing polymer and polyacrylic acid components, mixing an appropriate amount of these concentrates with a larger volume of water, adding any additional components used, and finally adjusting to the final desired volume or mass by the ad ⁇ dition of more water. These compositions are then applied to aluminum surfaces in the same manner as described for Example 14.
• the specific active ingredients and concentrations or amounts thereof in the treatment composition for each example are as follows:
• Example 15 4.1 g/1 of AcrysolTM A-l; 4.0 g/1 of GohsenolTM GLO-5; and 1.2 g/1 of hexafluorozirconic acid.
• Example 16 4.1 g/1 of AcrysolTM A-l and 0.6 g/1 of polyethylene glycol having a molecular weight of less than about 600,000.
• Example 17 4.1 g/1 of AcrysolTM A-l; 0.6 g/1 of polyethylene glycol having a molec ⁇ ular weight of less than about 600,000; and 1.2 g/1 of hexafluorozirconic acid.
• Example 18 4.1 g/1 of AcrysolTM A-l and 0.8 g/1 of dextrin.
• Example 19 4.1 g/1 of AcrysolTM A-l; 0.8 g/1 of dextrin; and 1.2 g/1 of hexafluoroti- tanic acid.
• Example 20 651.4 parts of deionized water; 83.7 parts of 60 % aqueous fluotitanic acid; 5.3 parts of Cab-O-SilTM M-5 fumed amorphous silicon dioxide; 14.6 parts of zirconium basic carbonate; 200.0 parts of AccumerTM 1510, a commercially available product from Rohm and Haas containing 25 % solids of polymers of acrylic acid with a molecular weight of about 60,000; and 55.0 parts of GohsenolTM GLO-5.

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• 1995
  • 1995-05-08 EP EP95918314A patent/EP0824565B1/de not_active Expired - Lifetime
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