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
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
• • 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
• • 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
  • C23C22/42—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 phosphates
• • 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
  • 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
  • C23C22/46—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 oxalates
• • 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
  • C23C2222/20—Use of solutions containing silanes

Definitions

• This invention relates to a surface treatment agent that can form a highly corrosion-resistant, strongly paint-adherent film on the surface of a metal, e.g., steel sheet, zinciferous-plated steel sheet, and aluminum sheet.
• the invention also relates to a process for treating metal surfaces using this surface treatment agent.
• Zinciferous-plated steel sheet is used in a variety of fields, for example, in automotive applications, for household electrical appliances, and as a building material. Since zinciferous-plated steel sheet corrodes upon exposure to the atmosphere with the production of a corrosion product known as white rust, it has heretofore typically been treated with a treatment composition containing an aqueous chromic acid solution in order to improve its corrosion resistance. This treatment, known as a chromate treatment, forms a coating layer that contains hexavalent chromium and trivalent chromium on the surface of zinciferous-plated steel sheet.
• An object of this invention is to solve the problems described above for the prior art by providing a liquid surface treatment composition for application to metals that can form a highly corrosion-resistant, strongly paint-adherent coating on metal surfaces and particularly on the surface of zinciferous-plated steel sheet.
• An alternative and/or concurrent object of this invention is to provide a process for treating metal surfaces that uses this surface treatment composition.
• a highly corrosion-resistant, strongly paint-adherent coating can be formed on metal surfaces by treating such surfaces with an aqueous liquid that, in addition to water, comprises, preferably consists essentially of, or more preferably consists of:
• each molecule contains at least two moieties that conform to general formula (I):
• each of R ⁇ R 2 , and R 3 is independently selected from the group consisting of hydrogen atoms and alkyl moieties containing from 1 to 4 carbon atoms; and (A.2) for all of the molecules considered together, the weight average value for the molecular weight divided by the average number per molecule of moieties conforming to formula (I) as given above yields a quotient that is within a range from 100 to 30,000; and
• organic acids phosphoric acid, hydrofluoric acid, tetrafluoroboric acid, hexafluorosilicic acid, hexafluorotitanic acid, hexafluorozirconic acid, and hexafluorohafnic acid.
• a liquid treatment composition according to the invention also contains a component (C) selected from the group consisting of resins each of the molecules of which contains at least one tertiary amino moiety or quaternary ammonium moiety but does not qualify to be part of component (A).
• component (C) selected from the group consisting of resins each of the molecules of which contains at least one tertiary amino moiety or quaternary ammonium moiety but does not qualify to be part of component (A).
• the weight of component (A) preferably has a ratio to the weight of component (C) in the same composition that is from 1.0:9 to 9:1.0, the weights of components (A) and (C) being measured in the same units.
• a liquid treatment composition according to the invention also contains a component (D) selected from the water soluble salts of the metals cobalt, tungsten, vanadium, magnesium, aluminum, manganese, titanium, trivalent chromium, and molybdenum, exclusive of any such salts that could be part of any of components (A), (B), and (C) as described above but inclusive of salts in which the metals are part of oxycations as well as salts in which the metals are cations.
• a component (D) selected from the water soluble salts of the metals cobalt, tungsten, vanadium, magnesium, aluminum, manganese, titanium, trivalent chromium, and molybdenum, exclusive of any such salts that could be part of any of components (A), (B), and (C) as described above but inclusive of salts in which the metals are part of oxycations as well as salts in which the metals are cations.
• component (D) When component (D) is present in a composition according to the invention, its weight preferably has a ratio to the weight of component (A) in the same composition that is from 0.00010:1.0 to 1.0:1.0, the weights of components (A) and (D) being measured in the same units.
• component (E) is present in a composition according to the invention, its weight preferably has a ratio the weight of component (A) in the same composition that is from 0.0010:1.0 to 1.0:1.0, the weights of components (A) and (E) being measured in the same units.
• a process according to this invention for treating metal surfaces is characterized by the formation of a liquid coating of a composition according to the invention on the surface of a metal substrate, and later, or preferably immediately, drying said surface treatment composition into place on said metal surface, without removing, e.g., by rinsing away, any of the non-volatiles content of the liquid coating before the coating is dried.
• the coating film so formed should have a mass per unit area, often called
• coating weight' that is from 0.1 to 3.0 grams of dried coating per square meter of metal surface coated, a unit of coating weight that is hereinafter usually abbreviated as "g/m 2 ",
• Components (A) and (B) are the necessary active ingredients in a liquid surface treatment composition according to the invention.
• the weight average value for the molecular weight of component (A) divided by the average number per molecule of moieties conforming to formula (I) as given above in component (A) preferably has a value that is at least, with increasing preference in the order given, 120, 130, 140, 150, or 160 and independently preferably is not more than, with increasing preference in the order given, 10,000, 5000, 2000, 1500, 1000, or 800. Synthesis of a compound in which the molecular weight per functional group is below 100 is highly problematic. Adherence to the metal surface, which is a characteristic function of this functional group, declines when the value of the molecular weight per functional group exceeds 30,000.
• component (A) While the process for synthesizing component (A) is not critical, this component can be synthesized, for example, by reacting chlorosilane with a compound bearing at least two active hydrogen-containing functional groups, by reacting two or more different silane coupling agents with each other, by reacting a reactive functional group-containing compound with the organofunctional groups in a silane coupling agent, and by copolymerizing a vinyl-functional silane coupling agent with other copolymerizable vinyl compound(s).
• the use, as part of component (A), of molecules containing only one moiety conforming to general formula (I) in each molecule is undesirable because the presence of such molecules gives a diminished adherence to metal surfaces.
• Organic acids which are preferred over their salts, are advantageous constituents of component (B) as described above when treating zinc-coated steel, because organic acids do not strongly etch the zinc-coated steel sheet and nevertheless remove the very thin oxide film present on the surface of the plating. Strong acids such as sulfuric acid, hydrochloric acid, and nitric acid reduce the corrosion resistance because they remove too much of the zinc coating.
• the subject organic acid can be exemplified by formic acid, acetic acid, butyric acid, oxalic acid, succinic acid, lactic acid, L-ascorbic acid, tartar ic acid, citric acid, DL-malic acid, malonic acid, maleic acid, and phthalic acid.
• Phosphoric acid is believed to increase the corrosion resistance by forming a zinc phosphate conversion coating — albeit in very small amounts — on the surface of a zinciferous coating.
• Usable as this phosphoric acid are, for example, metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, triphosphoric acid, and tetraphosphoric acid and the ammonium, aluminum, and magnesium salts of these acids.
• Fluoride when present as part of component (B) is believed to improve the corrosion resistance through a controlled etching activity and ability to chelate metal cations.
• component (B) has somewhat different preferred concentrations relative to component (A).
• organic acids when organic acids are used, their concentration preferably is at least, with increasing preference in the order given, 0.01 , 0.05, 0.10, 0.50, 1 .0, 3.0, or 4.0 and independently preferably is not more than, with increasing preference in the order given, 300, 200, 100, 75, 50, 25, 20, 10, or 6 parts by weight;
• phosphoric acid when phosphoric acid is used, its concentration preferably is at least, with increasing preference in the order given, 0.05, 0.10, 0.50, 1.0, 3.0, or 4.0 and independently preferably is not more than, with increasing preference in the order given, 200, 100, 75, 50, 25, 20, 10, or 6 parts by weight;
• complex fluorides when complex fluorides are used, their concentration preferably is at least 0.01 , 0.05, 0.10, 0.50, 1.0, 3.0, 6.0, or 9.0 and independently preferably is not more than
• component (C) a resin whose molecules contain at least one tertiary amino moiety or quaternary ammonium moiety. While the type of resin is not critical, a general-purpose predominantly polyacrylic, epoxy, polyurethane, or polyester resin is preferred. The technique for introducing tertiary amino and/or quaternary ammonium moieties is also not critical.
• Component (C) when used preferably has a concentration that will result in a ratio by weight of component (A) to component (C) that is at least, with increasing preference in the order given, 1.00:9.0, 1.00:7.0, 1.00:6.0, or 1.00:5.0 and independently preferably is not more than, with increasing preference in the order given, 9.0:1.00, 7.0:1.00, 6.0:1.00, or 5.0:1.00.
• the corrosion resistance is diminished when this ratio of (A)/(C) is below 1.0:9.
• only a weak effect is generated by the addition of component (C) when (A)/(C) is above 9:1.0, making such a use of component (C) uneconomical.
• component (D) preferably is present in an amount such that its ratio by weight to component (A) in the same treatment composition is at least, with increasing preference in the order given, 0.00010:1.0, 0.0005:1.00, 0.0010:1.00, 0.0050:1.00, 0.0100:1.00, 0.050:1.00, 0.070:1.00, 0.090:1.00, or 0.10:1.00 and independently preferably is not more than, with increasing preference in the order given, 1.00:1.00, 0.80:1.00, 0.70:1.00, 0.60:1.00, or 0.50:1.00. Little or no improvement in corrosion resistance is seen from a component (D) addition below 0.00010:1.0, while a component (D) addition above 1.0:1.0 is uneconomical since no additional benefit results from such an addition.
• component (E) When component (E) is present, it preferably is present in an amount such that the ratio by weight of component (E) to component (A) in the same composition is at least, with increasing preference in the order given, 0.0010:1.0, 0.0050:1.00, 0.010:1.00, 0.030:1.00, 0.050:1.00, 0.070:1 .00, 0.080:1.00, 0.090:1.00, or 0.097:1.00 and independently preferably is not more than, with increasing preference in the order given, 1.00:1.00, 0.50:1.00, 0.40:1 .00, 0.30:1.00, 0.20:1.00, or 0.12:1.00. Little or no improve- ment in corrosion resistance is obtained from a component (E) ratio below 0.0010:1.0, while the paint adherence is reduced when the (E)/(A) ratio is more than 1.0:1.0.
• the surface treatment composition of this invention may also contain: additives such as thickeners and surfactants (the latter also known as wetting agents) for the purpose of generating a uniform coating on the substrate surface; electrical conductivity im- provers in order to improve the welding behavior; colored pigments in order to improve the aesthetics, and film-forming auxiliaries in order to improve the film-forming performance.
• additives such as thickeners and surfactants (the latter also known as wetting agents) for the purpose of generating a uniform coating on the substrate surface
• electrical conductivity im- provers in order to improve the welding behavior
• colored pigments in order to improve the aesthetics
• film-forming auxiliaries in order to improve the film-forming performance.
• the surface treatment composition of this invention is preferably applied, for example, to: aluminum sheet; steel sheet, e.g., cold-rolled steel sheet and hot-rolled steel sheet; and, most preferably, zinciferous-plated steel sheet, e.g., electrogalvanized steel sheet, hot-dipped galvanized steel sheet, galvannealed steel sheet, steel sheet plated with aluminum-containing zinc, Zn/Ni-plated steel sheet, Zn/Co-plated steel sheet, and vapor-deposition zinc-plated steel sheet.
• zinciferous-plated steel sheet e.g., electrogalvanized steel sheet, hot-dipped galvanized steel sheet, galvannealed steel sheet, steel sheet plated with aluminum-containing zinc, Zn/Ni-plated steel sheet, Zn/Co-plated steel sheet, and vapor-deposition zinc-plated steel sheet.
• a coating with a weight after drying of 0.1 to 3.0 g/m 2 is preferably formed by application of a surface treatment composition according to the invention to the metal surface by, for example, roll coating, dipping, or electrostatic coating, followed by drying by induction heating or with a hot gas current to an attained sheet temperature of 60 to 250 °C and preferably 80 to 220 °C.
• the performance of the resulting coating may often be unsatisfactory when the attained sheet temperature does not reach 60 °C, while an attained sheet temperature in excess of 250 °C can result in pyrolysis of the coating.
• the performance of the coating may often be unsatisfactory when the coating weight is less than 0.1 g/m 2 , while no additional increments in coating performance are obtained at above 3.0 g/m 2 , making such weights uneconomical.
• the solids concentration in the surface treatment composition of the invention is preferably in the range from 1 to 50 %. Since the surface treatment composition is an aqueous system, a solids concentration below 1 % is undesirable because such concentrations result in long drying times. At the other end of the range, a solids concentration in excess of 50 % is undesirable because concentrations at this level cause such problems as a reduced dispersion stability and an increased viscosity of the treatment agent. Because a composition according to the invention is dried into place on the surface being treated in a process according to the invention, the concentration of the surface treatment composition has little or no technical effect on the results obtained, provided that a preferred coating weight as described above is obtained.
• a preferred coating weight can be obtained with either a thick coating of a dilute surface treatment liquid or a thin coating of a concentrated surface treatment liquid.
• This invention is illustrated in more specific terms in the following through working and comparative examples, but the scope of the invention is not limited by the working examples that follow. Described immediately below are the test specimens, degreasing treatment, and process for applying the metal surface treatment composition that were used in the working and comparative examples. 1. Preparation of the test specimens (1 -1 ) Materials tested
• coating weight 20 grams of electroplated zinc per square meter of steel sheet on both major surfaces, the unit of grams per square meter being hereinafter usually abbreviated as “g/m2” and coating on both major surfaces being hereinafter indicated by numbers with a virgule between them, so that the abbreviated description of this coating would be "20/20 g/m2";
• G galvannealed (Zn-Fe) hot-dip zinc-coated steel sheet
• A-1100 aluminum sheet hereinafter usually abbreviated as "AL"
• the metal surface treatment composition (see below for details) was applied with a bar coater. This was followed by drying at an ambient temperature of 300 °C. 2. Painted sheet performance testing
• + + rust produced over at least 3 % but less than 10 % of the total surface area
• + rust produced over at least 10 % but less than 30 % of the total surface area
• x rust produced over at least 30 % of the total surface area
• + + rust produced over at least 10 % but less than 20 % of the total surface area
• TREATMENT COMPOSITION A An amount of 5 parts by weight of ammonium dihydrogen phosphate as component (B) was added to 100 parts by weight of the compound afforded by the reaction in ethanol of 1.0 mole of hexamethylenediamine and 2.0 moles of ⁇ -glycidoxypropyltrime- thoxysilane as component (A). The resulting mixture was diluted with deionized water to give a solids concentration of 5 %.
• Component (A) in this instance had 2 moieties conforming to formula (I) per molecule, and its ratio of gram molecular weight to the number of such moieties per molecule was approximately 294.
• component (B) An amount of 5.0 parts by weight of oxalic acid as component (B) was added to 100 parts by weight of the compound(s) afforded by the reaction in N-methyl-2-pyrroli- done of 1.0 mole of bisphenol-A epoxy resin (EPONTM 828 type, hereinafter usually abbreviated as "#828 type") and 2.0 moles of ⁇ -aminopropyltriethoxysilane as component (A). The resulting mixture was diluted with deionized water to give a solids concentration of 5 %.
• Component (A) in this instance had 2 moieties conforming to formula (I) per molecule, and its ratio of gram molecular weight to the number of such moieties per molecule was approximately 411 .
• composition A as described above was added 20 parts by weight, per 100 parts by weight of component (A), of the polymer(s) afforded by the emulsion polymerization in deionized water of 1 .0 mole of acrylic acid, 5.0 moles of methyl methacrylate, 3.0 moles of 2-hydroxyethyl methacrylate, and 2.0 moles of dimethylaminoethyl methacrylate as component (C).
• the resulting mixture was diluted with deionized water to give a solids concentration of 5 %.
• the component (A)/component (C) weight ratio was 5:1.0.
• TREATMENT COMPOSITION F To Treatment Composition C as described above was added 500 parts (solids) by weight, per 100 parts by weight of component (A), of a water-based urethane resin containing tertiary amino and quaternary ammonium moieties (Adeka BontiterTM HUX 670, registered trademark of Asahi Denka Kogyo Kabushiki Kaisha) as component (C). The resulting mixture was diluted with deionized water to a solids concentration of 5 %. The component (A)/component (C) weight ratio was 1.0:5.0. TREATMENT COMPOSITION G
• composition A As described above was added 10 parts by weight, per 100 parts by weight of component (A), of anhydrous magnesium acetate as component (D). The resulting mixture was diluted with deionized water to give a solids concentration of 5 %.
• composition C As described above was added 30 parts by weight, per 100 parts by weight of component (A), of aluminum phosphate (AIPO 3 ) as component (D). The resulting mixture was diluted with deionized water to give a solids concentration of 5%.
• TREATMENT COMPOSITION J To Treatment Composition A as described above was added 10 parts by weight, per 100 parts by weight of component (A), of 2-butyn-1 ,4-diol (HOCH 2 C ⁇ CCH 2 OH) as component (E). The resulting mixture was diluted with deionized water to give a solids concentration of 5 %.
• TREATMENT COMPOSITION K To Treatment Composition A as described above was added 10 parts by weight, per 100 parts by weight of component (A), of 2-butyn-1 ,4-diol (HOCH 2 C ⁇ CCH 2 OH) as component (E). The resulting mixture was diluted with deionized water to give a solids concentration of 5 %.
• Amounts of 5 parts by weight, per 100 parts by weight of component (A), of ammonium dihydrogen phosphate as part of component (B) and 10 parts by weight, per 100 parts by weight of component (A), of ammonium fluorosilicate as the remainder of component (B) were added to 100 parts by weight of the compound(s) afforded by the reaction in ethanol of 1 mole hexamethylenediamine and 2 moles of ⁇ -glycidoxypropyltri- methoxysilane as component (A).
• the resulting mixture was diluted with deionized water to give a solids concentration of 5 %.
• Component (A) in this instance had 2 moieties conforming to formula (I) per molecule, and its ratio of gram molecular weight to number of such moieties per molecule was approximately 294.
• component (A) in this instance had 2 moieties conforming to formula (I) per molecule, and its ratio of gram molecular weight to number of such moieties per molecule was approximately 171.
• the ratio by weight of component (A) to component (C) was 1.0:2.0.
• COMPARATIVE TREATMENT COMPOSITION Q An amount of 10 parts by weight of ammonium fluosilicate, which in itself would be suitable to constitute component (B) of a composition according to this invention, was added to 100 parts by weight of the compound(s), with an average molecular weight of approximately 40,000, afforded by the emulsion polymerization in deionized water of 50 moles of acrylic acid, 100 moles of butyl acrylate, 100 moles of methyl methacrylate, 100 moles of 2-hydroxyethyl methacrylate, and 1.0 mole ⁇ -methacryloxypropyltriethoxysilane as the closest to a proper component (A) as described above.
• component (A) was diluted with deionized water to give a solids concentration of 5 %.
• What might otherwise be component (A) in this instance had an average of only 1 moiety conforming to formula (I) per molecule, and its ratio of gram molecular weight to number of such moieties per molecule was approximately 40,000 — a value outside the range specified for component (A) according to the present invention.
• This treatment composition was produced by the suitable dilution of Zinchrom® 3360H chromate treatment agent, a product commercially available from Nihon Parkerizing Co., Ltd. and intended for imparting temporary corrosion resistance to zinc- coated steel sheet.
• This treatment composition was produced by the suitable dilution of Zinchrom® 3383 chromate treatment agent, a product commercially available from Nihon Parkerizing Co., Ltd. and intended for imparting intermediate corrosion resistance to zinc-coated steel sheet. 4. Test results
• Table 1 reports the Example and Comparative Example numbers associated with the metal surface treatment compositions identified by letters above, while Table 2 reports the results of painted sheet performance testing using the metal surface treatment compositions.
• Numbers 1 through 25 in Table 2 refer to experiments in which coatings were formed by application of a metal surface treatment composition according to the invention. Good values were obtained in all performance categories (flat region corrosion resistance, worked region corrosion resistance, overcoated paint adherence) in all of these experiments.
• Numbers 27 to 31 in Table 2 refer to experiments that used the treatment agents of Comparative Examples 1 through 5 in Table 1 — treatment agents that fell outside the scope of the present invention. These latter experiments gave relatively poor results for at least one, and often all, of the flat region corrosion resistance, worked region corrosion resistance, and overcoated paint adherence.
• Table 1 reports the Example and Comparative Example numbers associated with the metal surface treatment compositions identified by letters above, while Table 2 reports the results of painted sheet performance testing using the metal surface treatment compositions.
• Numbers 1 through 25 in Table 2 refer to experiments in which coatings were formed by application of a metal

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