Composition and process for treating the surface of aluminiferous metals

A highly corrosion resistant and paint adherent surface coating on aluminiferous metals can be provided very rapidly, if desired in less than one second, by contacting the surface with an aqueous acid liquid treating composition containing as solutes specified proportions of phosphate ions, titanium containing materials, fluoride, and an accelerator, the accelerator is preferably at least one of nitrous acid, nitric acid, tungstic acid, molybdic acid, permanganic acid, water soluble salts of all of these acids, and water-soluble organoperoxides.

TECHNICAL FIELD
 This invention relates to a novel liquid surface treatment composition and
 process for application to aluminiferous metals, which provide the surface
 of aluminiferous metals, i.e., aluminum and aluminum alloys containing at
 least 65% by weight of aluminum, with an excellent corrosion resistance
 and paint adherence. The present invention is applied with particularly
 good effect in the surface treatment of aluminum alloys in coil and sheet
 form.
 BACKGROUND ART
 Liquid compositions, which hereinafter are often called "baths" for
 brevity, even if used by some other method than immersion, that are in
 general use for treating the surface of aluminiferous metals can be
 broadly classified into chromate types and nonchromate types. Chromic acid
 chromate conversion baths and phosphoric acid chromate conversion baths
 are typical embodiments of chromate type treatment baths.
 Chromic acid chromate conversion baths came into practical use in about
 1950 and are still widely used even at present for heat exchanger fin
 stock and aviation vehicle components. The chromic acid chromate
 conversion baths contain chromic acid and fluoride as their main
 components, with the fluoride functioning as a reaction accelerator. These
 baths coat metal surfaces with conversion coatings containing some
 quantity of hexavalent chromium.
 Phosphoric acid chromate conversion baths originated with the invention
 disclosed in U.S. Pat. No. 2,438,877. These conversion baths, which
 contain chromic acid, phosphoric acid, and hydrofluoric acid as their main
 components, coat metal surfaces with conversion coatings whose main
 component is hydrated chromium phosphate. Because these conversion
 coatings do not contain hexavalent chromium, they also are in wide use at
 present, for such applications as underpaint coatings for beverage can
 body and lid stock. Nevertheless, since these chromate type surface
 treatment baths do themselves contain toxic hexavalent chromium even
 though the coatings produced by them do not, hexavalent chromium-free
 treatment baths are desired in view of the environmental problems from
 disposal of the baths, rinse waters, and the like.
 Typical of the inventions in the field of the chromium-free nonchromate
 type surface treatment baths is the process disclosed in Japanese Patent
 Application Laid Open [Kokai or Unexamined] Number Sho 52-131937
 [131,937/1977]. The treatment bath in that reference consists of an acidic
 (pH approximately 1.5 to 4.0) aqueous coating solution containing
 phosphate, fluoride, and zirconium or titanium or both. Treatment of the
 metal surface with this surface treatment bath forms thereon a protective
 coating whose main component is zirconium or titanium oxide. (This type of
 coating is often called a "conversion" coating, because it is believed
 that it also contains cations from the substrate in the form of oxides
 and/or phosphates.) An advantage of nonchromate surface treatment baths is
 that they are free of hexavalent chromium, and this advantage has resulted
 in their wide use at the present time for treating the surface of
 drawn-and-ironed ("DI") aluminum cans and the like. However, the
 nonchromate baths require longer treatment times for coating formation
 than chromate surface treatment baths. Shortening surface treatment times
 has become an important issue in the last few years, because of the
 increasingly high line speeds being used to boost productivity. Moreover,
 nonchromate baths yield coatings with a corrosion resistance and paint
 adherence inferior to those of chromate coatings.
 The treatment process disclosed in Japanese Patent Application Laid Open
 [Kokai or Unexamined] Number Hei 1-246370 [246,370/1989] is an invention
 whose object is to shorten the aforementioned surface treatment times. In
 this process, the aluminiferous metal surface is first cleaned with an
 alkaline degreaser and the cleaned surface is then treated with an acidic
 (pH 1.5 to 4.0) aqueous solution containing 0.01 to 0.5 g/L of zirconium
 ions, 0.01 to 0.5 g/L of phosphate ions, 0.001 to 0.05 g/L, measured as
 its stoichiometric equivalent as fluorine atoms, of "free" fluoride ions,
 and optionally 0.01 to 1 g/L of vanadium ions. However, when this process
 is applied to DI aluminum cans, the resulting film does not always have a
 satisfactory resistance to blackening.
 Another nonchromate treatment process is disclosed in Japanese Patent
 Publication Number Sho 57-39314 [39,314/1982]. Disclosed therein is a
 treatment process in which the aluminiferous metal surface is treated with
 an acidic solution containing hydrogen peroxide, one or more selections
 from zirconium and titanium salts, and one or more selections from
 phosphoric acid and condensed phosphoric acids. However, this treatment
 bath is unstable, and, in addition, is also inadequately rapid in terms of
 surface coating formation. Moreover, this document does not provide a
 specific description or disclosure of the treatment time, treatment
 temperature, or treatment process.
 It is for these reasons that nonchromate type surface treatment baths are
 at present almost never used on surface treatment lines for aluminiferous
 metal coil or sheet where short treatment times are critical.
 In summary, then, there has yet to become established in the art a
 composition or process for treating the surface of aluminiferous metals
 that can provide short treatment times and is capable of forming a highly
 corrosion-resistant and strongly paint-adherent coating, but is free of
 hexavalent chromium.
 DISCLOSURE OF THE INVENTION
 Problem(s) to Be Solved by the Invention
 The present invention is directed to solving the problems described above
 for the prior art. In specific terms, the present invention provides a
 composition and process for treating the surface of aluminiferous metals
 that are able to form rapidly a very corrosion-resistant and highly
 paint-adherent coating on the surface of aluminiferous metals.
 SUMMARY OF THE INVENTION
 It has been discovered that a surface treatment composition containing
 dissolved phosphate ions, dissolved titanium containing substance(s), and
 dissolved fluoride in particular relative quantities and a particular
 relative quantity of accelerator selected from a specific group of
 chemical substances can rapidly form a very corrosion-resistant and highly
 paint-adherent coating on the surface of aluminiferous metals. The present
 invention was achieved based on this discovery.
 A concentrate or working composition according to the present invention for
 treating the surface of aluminiferous metals characteristically comprises,
 preferably consists essentially of, or more preferably consists of, water
 and the following materials in the relative proportions stated as follows:
 from 0.010 to 5 parts by weight of phosphate ions; from 0.010 to 2.0 parts
 by weight, calculated as its stoichiometric equivalent as titanium atoms,
 of dissolved titanium containing substance(s); from 0.010 to 12 parts by
 weight, calculated as its stoichiometric equivalent as fluorine atoms, of
 dissolved molecules and/or anions containing fluorine; and from 0.010 to
 2.0 parts by weight of dissolved accelerator. The bases for the
 specification of these particular weight proportions for each component
 will be explained in sequence in the discussion of the composition of
 preferred surface treatment baths, vide infra. Counterions for the
 necessary constituents explicitly recited above are also necessary if
 needed for electrical neutrality.
 The accelerator increases the speed of coating formation and is selected
 from the group consisting of oxyacids, such as tungstic acid (i.e.,
 H.sub.2 WO.sub.4), molybdic acid (i.e., HMoO.sub.3), permanganic acid
 (i.e., HMnO.sub.4), nitric acid (i.e., HNO.sub.3), nitrous acid (i.e.,
 HNO.sub.2), hypochlorous acid (i.e., HClO), chlorous acid (i.e.,
 HClO.sub.2), chloric acid (i.e., HClO.sub.3), bromic acid (i.e.,
 HBrO.sub.3), iodic acid (i.e., HIO.sub.3), perchloric acid (i.e.,
 HClO.sub.4), perbromio acid (i.e., HBrO.sub.4), periodic acid (i.e,
 HIO.sub.4), orthoperiodic acid (i.e., H.sub.5 IO.sub.6), and salts of
 oxyacids; peroxoacids, such as peroxomonosulfuric acid (i.e., H.sub.2
 SO.sub.5), peroxodisulfuric acid (i.e., H.sub.2 S.sub.2 O.sub.8),
 peroxomonophosphoric acid (H.sub.3 PO.sub.5), peroxodiphosphoric acid
 (i.e., H.sub.4 P.sub.2 O.sub.8), peroxomonocarbonic acid (i.e., H.sub.2
 CO.sub.4), peroxodicarbonic acid (i.e., H.sub.2 C.sub.2 O.sub.6), and any
 of the peroxoboric acids (i.e., HBO.sub.3.cndot.1/2H.sub.2 O,
 HBO.sub.4.cndot.H.sub.2 O, or HBO.sub.5.cndot.H.sub.2 O), and salts of
 peroxoacids; higher valent metal cations of metals with at least two
 stable cationic valence states, in cations that do not include oxygen, in
 aqueous solution, such as tetravalent cerium (i.e., Ce.sup.+4), trivalent
 iron (i.e., Fe.sup.+3), and tetravalent tin (Sn.sup.4+); hydrogen peroxide
 (H.sub.2 O.sub.2); and water-soluble organoperoxides. The use of an
 accelerator selected from this group in a treatment composition according
 to the present invention yields a substantial improvement in the speed of
 formation of a sufficiently thick coating to have protective qualities and
 in the corrosion resistance and paint adherence of the coating thereby
 formed.
 The four necessary active ingredients in a composition according to the
 invention as described above need not necessarily all be provided by
 separate chemical substances. For example, fluotitanic acid is well suited
 to be a single source of both titanium and fluoride.
 A process according to the present invention for treating the surface of
 aluminiferous metals characteristically comprises the formation thereon of
 a coating by bringing the surface of aluminiferous metal into contact, at
 a temperature from normal ambient temperature (i.e., at least 10 and more
 often at least 20.degree. C.) to 80.degree. C., with a surface treatment
 working composition, and thereafter subjecting the surface of the
 aluminiferous metal carrying the surface treatment bath to a rinse with
 water and, usually, drying, often with the use of heat.
 DETAILED DESCRIPTION OF THE INVENTION, INCLUDING PREFERRED EMBODIMENTS
 The source of the phosphate ions for a concentrate or working composition
 according to the present invention can be one or more selections from
 orthophosphoric acid (i.e., H.sub.3 PO.sub.4) and neutral and acid salts
 thereof and condensed phosphoric acids, such as pyrophosphoric acid (i.e.,
 H.sub.4 P.sub.2 O.sub.7) and tripolyphosphoric acid (i.e., H.sub.5 P.sub.3
 O.sub.10) and neutral and acid salts of any of these. The particular
 phosphate ions source selected is not critical, and the stoichiometric
 equivalent as phosphate ions from any of these sources is considered to be
 phosphate ions for determining whether a composition is according to the
 invention and if so, what its degree of preference is, irrespective of the
 actual extent of ionization and condensation to form chemical species with
 P--O--P bonds that may exist in solution. The phosphate ions content in a
 working bath according to the present invention is preferably from 0.010
 to 5.0 g/L, more preferably from 0.050 to 5.0 g/L, and even more
 preferably from 0.30 to 2.0 g/L. While a coating may be formed even at a
 phosphate ions concentration below 0.010 g/L, such coatings do not have an
 excellent corrosion resistance or paint adherence. The use of large
 concentrations--in excess of 5.0 g/L--is uneconomical: While good-quality
 coatings are formed at such levels, no additional benefits are obtained
 from the use of such large amounts, so that the cost of the treatment bath
 is raised without any offsetting benefit.
 The source of the titanium containing substance(s) in a working or
 concentrate composition according to the present invention preferably is
 either a salt containing titanium and/or titanyl cations, the anions of
 which salt can be sulfate, fluoride, or the like, or fluotitanic acid or
 at least one of its salts, but the selection of the titanium containing
 substance(s) is not critical. The titanium containing substance(s)
 concentration in a surface treatment bath according to the invention
 should be from 0.010 to 2.0 g/L and is preferably from 0.10 to 2.0 g/L or
 more preferably from 0.10 to 1.0 g/L, in each instance calculated as
 titanium. The rapid formation of a satisfactory coating becomes quite
 problematic at a titanium content below 0.010 g/L. The use of large
 amounts--in excess of 2.0 g/L--is uneconomical: While good-quality
 coatings are formed at such levels, no additional benefits are obtained
 from the use of such large amounts and the cost of the treatment bath is
 raised.
 The source of fluoride in the composition and surface treatment bath
 according to the present invention can be such fluorine-containing acids
 as hydrofluoric acid (i.e., HF), fluotitanic acid (i.e., H.sub.2
 TiF.sub.6), fluosilicic acid (i.e., H.sub.2 SiF.sub.6), and fluozirconic
 acid (i.e., H.sub.2 ZrF.sub.6), as well as any of their neutral and acid
 salts, but again the selection of the fluoride is not critical. The
 fluoride content in the surface treatment bath should be in the range from
 0.010 to 12 g/L, preferably is from 0.050 to 5.0 g/L, and more preferably
 is from 0.10 to 3.0 g/L, in each case calculated as fluorine.
 Aluminum ions eluting from the substrate are stabilized in the bath as
 aluminum fluoride by the fluoride, and the content levels given above
 include the quantity of fluoride necessary to do this. Aluminum fluoride
 has little effect on the coating-forming reactions. For example, a
 fluorine concentration of about 0.2 g/L is required in order to stabilize
 an aluminum concentration in the surface treatment bath of 0.1 g/L. Not
 counting the amount of fluorine required to produce aluminum fluoride, the
 optimal fluoride content for coating formation is from 0.010 to 5.0 g/L
 and preferably from 0.10 to 3.0 g/L, in each case calculated as fluorine.
 A fluorine content below 0.010 g/L results in an inadequate reactivity and
 hence in inadequate coating formation. On the other hand, levels in excess
 of 12 g/L result in an increased degree of etching that causes an
 undesirable unevenness in appearance, and such high levels also greatly
 complicate effluent treatment.
 The accelerator functions in a surface treatment process according to the
 present invention to accelerate the rate of formation of the titanium
 coating on the metal surface and also to induce the formation of a highly
 corrosion-resistant and strongly paint-adherent coating. The accelerator
 concentration in the surface treatment bath must be in the range from
 0.010 to 2.0 g/L and is preferably in the range from 0.10 to 1.1 g/L. No
 acceleration of the film-forming reaction is usually observed at an
 accelerator concentration below 0.010 g/L. The benefits from the
 accelerator do not further increase at accelerator levels in excess of 2.0
 g/L, so that additions in excess of this level simply raise costs and are
 thus uneconomical.
 An especially preferred accelerator includes at least one selection from
 the group consisting of nitrous acid, nitric acid, tungstic acid, molybdic
 acid, permanganic acid, all water-soluble salts of all of these acids, and
 water-soluble organoperoxides.
 The nitrous acid/nitrite source is not critical as long as it is
 water-soluble; however, the use of the sodium salt (i.e., NaNO.sub.2) or
 the potassium salt (i.e., KNO.sub.2) of nitrous acid is usually preferred
 because of their relatively low cost. The nitric acid/nitrate source is
 also not critical, again as long as it is water-soluble; however, the use
 of the sodium salt (i.e., NaNO.sub.3) or the potassium salt (i.e.,
 KNO.sub.3) of nitric acid (i.e., HNO.sub.3) or of nitric acid itself is
 preferred because of their relatively low cost.
 The tungstic acid/tungstate source is not critical as long as it is
 water-soluble; however, again the use of the sodium salt (i.e., Na.sub.2
 WO.sub.4) or potassium salt (i.e., K.sub.2 WO.sub.4) of tungstic acid is
 preferred because of their relatively low cost.
 The molybdic acid/molybdate source is not critical as long as it is
 water-soluble; however, the use of the sodium salt (i.e., Na.sub.2
 MoO.sub.4) or ammonium salt (i.e., (NH.sub.4).sub.6 Mo.sub.7 O.sub.24) of
 simple or condensed molybdic acid respectively is preferred because of
 their relatively low cost.
 The permanganic acid/permanganate selection is not critical as long as it
 is water-soluble; however, the use of the sodium salt (i.e., NaMnO.sub.4)
 or potassium salt (i.e., KMnO.sub.4) of permanganic acid is preferred
 because of their relatively low cost.
 Preferred examples of water-soluble organoperoxide are tert-butyl
 hydroperoxide (i.e., (CH.sub.3).sub.3 C--O--OH), tert-hexyl hydroperoxide
 (i.e., CH.sub.3 CH.sub.2 (CH.sub.3).sub.2 C--O--OH), and di-tert-butyl
 peroxide (i.e., (CH.sub.3).sub.3 C--O--O--C(CH.sub.3).sub.3).
 A working surface treatment bath according to the present invention is most
 conveniently prepared from a concentrate composition according to the
 present invention, and the pH of a working bath must be in the range from
 1.0 to 4.5. A pH below 1.0 causes an excessive etch of the metal surface
 by the treatment bath and thereby strongly impairs film formation. It
 becomes very problematic to obtain a highly corrosion-resistant and
 strongly paint-adherent coating at a pH in excess of 4.5. The more
 preferred pH range is 1.3 to 3.0. The pH of the surface treatment bath
 according to the present invention can be adjusted by adding an acid,
 e.g., nitric acid, sulfuric acid, hydrofluoric acid, or the like to lower
 the pH, or by adding an alkali, e.g., sodium hydroxide, sodium carbonate,
 ammonium hydroxide, or the like to raise the pH.
 When in the practice of the present invention the metal substrate is
 composed of an alloy of aluminum with copper or manganese, the stability
 of the treatment bath may be substantially impaired by dissolution into
 the surface treatment bath of metal ions derived from the copper or
 manganese alloying component. In such a case, a difunctional organic acid
 or its alkali metal salt may be added as metal sequestering agent in order
 to chelate the aforementioned alloying metal ions. Examples of suitable
 organic acids are gluconic acid, heptogluconic acid, oxalic acid, tartaric
 acid, and ethylenediaminetetraacetic acid.
 A working surface treatment bath according to the present invention may be
 brought into contact with the substrate to be treated by any convenient
 method and normally is used as part of a process sequence including other
 steps. A preferred generalized process sequence, for example, is as
 follows:
 1. Surface cleaning: degreasing with an acidic, alkaline, or solvent-based
 system
 2. Water rinse
 3. Surface treatment with treatment bath according to the present invention
 treatment temperature: ambient temperature to 80.degree. C. treatment
 time: 0.5 to 60 seconds treatment technique: spraying or dipping
 4. Water rinse
 5. Rinse with deionized water
 6. Drying.
 A treatment process according to the present invention is performed by
 bringing a working surface treatment bath as described above into contact
 with a surface of aluminiferous metal at from room temperature to
 80.degree. C. and preferably at from 35.degree. C. to 70.degree. C., for a
 contact time that is at least, with increasing preference in the order
 given, 0.50, 1.0, or 2.0 seconds and independently preferably is not more
 than, with increasing preference in the order given, 120, 90, 60, 50, 40,
 30, 20, 10, 8.0, 5.0, 3.0, or 2.5 seconds. Treatment times below 0.5
 second are associated with an insufficient reaction and hence may not
 yield the formation of a coating with good corrosion resistance and paint
 adherence. The properties of the coating do not usually improve further at
 treatment times above 120 seconds and in some instances do not improve
 further even after treatment times of a few seconds, while any extended
 treatment time increases the process cost.
 The coating formed in a process according to the invention preferably
 contains a mass per unit area of 3 to 50, or more preferably of 5 to 30,
 milligrams per square meter (hereinafter usually abbreviated as
 "mg/m.sup.2 ") of titanium atoms, which are measured as such by some
 method, such as X-ray fluorescence, that is independent of the chemical
 nature of the titanium atoms. When the surface coating mass is below 3
 mg/M.sup.2 as titanium, there is usually inadequate corrosion resistance
 by the resulting coating. At the other end of the range, there is usually
 an unsatisfactory paint adherence by the coating when the coating weight
 exceeds 50 mg/m.sup.2.
 The aluminiferous metals that may be subjected to surface treatment by a
 process according to the present invention encompass both pure aluminum
 and aluminum alloys, for example, Al--Cu, Al--Mn, Al--Mg, Al--Si, and
 Al--Zn alloys. The form and dimensions of the aluminiferous metal used in
 the invention process are not critical, and, for example, sheet and
 various molding shapes fall within the scope of the process.

Surface treatment baths and process according to the present invention will
 be illustrated in greater detail in the following through both working and
 comparison examples.
 EXAMPLES
 The treatment process sequence and other conditions outlined immediately
 below apply to each of Examples 1 to 9 and Comparison Examples 1 to 7.
 Sample Material
 Aluminum-magnesium alloy sheet according to Japanese Industrial Standard
 (hereinafter usually abbreviated as "JIS") 5182 was used.
 Dimensions: 300 millimeters (hereinafter usually abbreviated as
 "mm").times.200 mm.
 Sheet thickness: 0.25 mm
 Treatment Conditions
 The conversion-treated sheet was prepared by the execution of the following
 processes in the sequence 1.fwdarw.2.fwdarw.3.fwdarw.4.fwdarw.5.fwdarw.6.
 1. Degreasing (60.degree. C., 10 seconds, spray) A 2% aqueous solution of a
 commercially available alkaline degreaser, FINECLEANER.RTM. 4377K from
 Nihon Parkerizing Company, Limited, was used.
 2. Water rinse (ambient temperature, 10 seconds, spray)
 3. Metal treatment according to the invention or a comparison thereto
 (spray)
 The components used in the surface treatment baths, their concentrations in
 these baths, and the conditions for the processes according to the
 invention in Examples 1 to 9 and for Comparison Examples 1 to 5 are shown
 in tables below. The surface treatment conditions for Comparison Examples
 6 and 7 are noted separately. An aqueous solution of 40% fluotitanic
 acid--a compound that is both a titanium containing substance(s) and a
 fluoride--was used in Examples 1, 4, 7, and 9 and in Comparison Example 2
 as the source of both of these necessary components of a bath according to
 the invention. The entire amount of fluotitanic acid used is shown in the
 tables below under one column heading as a titanium source and under
 another heading as a fluoride source, but the amount was not in fact
 duplicated in the working bath. An aqueous solution of 67.5% nitric acid
 was used both as an accelerator and for pH adjustment in Examples 1 and 5.
 4. Water rinse (ambient temperature, 10 seconds, spray)
 5. Rinse with deionized water (ambient temperature, 5 seconds, spray)
 6. Heating and drying (80.degree. C., 3 minutes, hot-air oven)
 A small sprayer was used for the degreasing, water rinse, rinse with
 deionized water, and treatment according to the invention or a comparison
 thereto. The particular small sprayer used was designed to reproduce the
 same spraying conditions as in a continuous surface treatment line for the
 actual treatment of aluminum alloy coil.
 The following methods were used to test the coating weight, corrosion
 resistance, and paint adherence of the treated specimens.
 (1) Coating Weight
 The Ti or Zr add-on, in mg/m.sup.2 on the treated sheet was measured using
 a fluorescent x-ray analyzer (RIX1000 from Rigaku Denki Kogyo Kabushiki
 Kaisha).
 (2) Corrosion Resistance
 Salt-spray testing according to JIS Z 2371 was used to evaluate the
 corrosion resistance. The development of corrosion on the treated sheet
 was visually evaluated after 150 hours of salt-spray testing, and the
 results were scored according to the following scale:

+++: corroded area was less than 10%;
 ++: corroded area was greater than or equal to 10%, but less
 than 50%;
 +: corroded area was greater than or equal to 50%, but less
 than 90%;
 x: corroded area was greater than or equal to 90%.
 (3) Paint Adherence
 The surface of the conversion-treated aluminum-magnesium alloy sheet was
 painted with an epoxy-phenol paint for can lids to give a paint film
 thickness of 8 micrometers followed by baking for 3 minutes at 220.degree.
 C. Polyamide film was then inserted between two of these painted surfaces
 with hot-press bonding at 200.degree. C. for 2 minutes. The hot-press
 bonded composite was cut into 10 mm wide.times.120 mm long strips, which
 were the test specimens. A test specimen was peeled from the polyamide
 film using the T-peel test procedure, and the peel strength at this point
 was designated as the primary adherence. In order to evaluate the
 durability of the adherence to water, a test specimen prepared as
 described above was dipped in boiling deionized water for 60 minutes and
 then submitted to measurement of the peel strength in the same T-peel test
 procedure. The result in this case was designated as the secondary
 adherence.
 Larger values for the peel strength are indicative of a better paint
 adherence. A performance sufficient for practical applications was a peel
 strength of at least 7.0 kilograms-force (hereinafter usually abbreviated
 as "kgf")/10 mm width in the case of the primary adherence and a peel
 strength of at least 5.0 kgf/10 mm width in the case of the secondary
 adherence.
 Comparison Example 6
 The same treatment process was run as in Example 1, except for using a 2%
 aqueous solution of a commercially available zirconium-based treatment
 agent, ALODINE.TM. 4040 from Nihon Parkerizing Company, Limited, as the
 surface treatment bath in process step 3. This treatment bath was sprayed
 on the same aluminum-magnesium alloy sheet as described above for 30
 seconds at 40.degree. C. The test results are reported in tables below.
 Comparison Example 7
 The same treatment was run as in Example 1, except for using a 2% aqueous
 solution of a commercially available zirconium-based treatment agent,
 ALODINE.TM. 4040, from Nihon Parkerizing Company, Limited, as the
 treatment bath. This bath was sprayed on the same aluminum-magnesium alloy
 sheet as described above for 5 seconds at 40.degree. C. The test results
 are reported in tables below.
 Benefits of the Invention
 As the preceding description has made clear, application of a working
 treatment composition in a surface treatment process according to the
 present invention to aluminiferous metals rapidly forms a highly
 corrosion-resistant and strongly paint-adherent coating on the metal
 surface prior to the painting or forming thereof. Moreover, when the
 substrate aluminiferous metal is in the form of continuous coil or sheet,
 rapidity of the treatment supports higher production line speeds and
 permits compactness (space savings) of the treatment facilities.
 In consequence of these effects, surface treatment concentrates, working
 baths, and processes according to the present invention for application to
 aluminiferous metals have a very high degree of practical utility.
 TABLE 1
 COMPONENTS USED IN THE TREATMENTS OF EXAMPLES 1 TO 9 AND
 COMISON EXAMPLES 1 TO 5, AND IDENTIFYING SYMBOLS
 THEREFOR
 Source Material(s)
 Chemical
 Component Compound Formula Symbol
 Phosphate ions 85% Orthophosphoric acid in water H.sub.3 PO.sub.4 a
 Titanium 40% Fluotitanic acid in water H.sub.2 TiF.sub.6 A
 containing 24% Titanic sulfate in water Ti(SO.sub.4).sub.2 B
 substance(s) Titanyl sulfate in water, 10% Ti TiOSO.sub.4 C
 Fluoride 40% Fluotitanic acid in water H.sub.2 TiF.sub.6 A
 20% Hydrofluoric acid in water HF a
 40% Fluosilicic acid in water H.sub.2 SiF.sub.6 b
 96% Ammonium acid fluoride in water NH.sub.4 HF.sub.2 c
 Accelerator 67.5% Nitric Acid in water HNO.sub.3 T
 Potassium permanganate KMnO.sub.4 U
 97% Pure Sodium Nitrite NaNO.sub.2 V
 Sodium tungstate dihydrate Na.sub.2 WO.sub.4.2H.sub.2 O W
 Ammonium heptamolybdate (NH.sub.4).sub.6 Mo.sub.7
 O.sub.24.4H.sub.2 O X
 tetrahydrate
 69% Tert-butyl hydroperoxide in water (CH.sub.3).sub.3
 C--O--OH Y
 5% Stannic chloride in water SnCl.sub.4 Z
 pH Regulator 67.5% Nitric acid in water HNO.sub.3 T
 97% Sulfuric acid in water H.sub.2 SO.sub.4 a
 25% ammonia in water NH.sub.4 OH b
 TABLE 2
 COMPOSITIONS OF SURFACE TREATMENT BATHS ACCORDING TO
 THE INVENTION
 Grams per Liter in Bath of:
 Ti Com- Phosphate Fluoride Accelerator pH pH
 Example pound/ Source/ Source/ Source/(Active Regulator of
 Number (Ti) (PO.sub.4.sup.-3) (F) Accelerator) Type
 Bath
 1 5.0 of A/ 1.0 of a/ 5.0 of A/ 1.00 of T/ T 1.3
 (0.58) (0.82) (1.39) (0.68)
 2 2.0 of C/ 0.2 of a/ 0.5 of a/ 0.10 of W/ a 1.8
 (0.20) (0.16) (0.10) (0.09)
 3 30.0 of B/ 4.0 of a/ 15.0 of a/ 0.50 of V/ a 1.0
 (1.44) (3.30) (2.85) (0.49)
 4 10.0 of A/ 1.0 of a/ 10.0 of A/ {1.00 of V/ b 1.5
 (1.17) (0.82) (2.78) (0.97)} + {0.10
 of U/(0.10)}
 5 20.0 of B/ 1.5 of a/ {0.5 of a/ {0.30 of T/ T 1.3
 (0.96) (1.24) (0.10} + (0.20)} + {0.05
 {0.5 of b/ of X/(0.05)}
 (0.16)
 6 5.0 of C/ 1.0 of a/ 2.0 of c/ {0.30 of Y/ b 4.2
 (0.48) (0.82) (1.28) (0.21)} + {0.10
 of W/(0.10)}
 7 {0.30 of 2.5 of a/ {3.0 of A/ 1.0 of Y/ b 2.5
 A/ (2.06) (0.83)} + (0.69)
 (0.35)} + {2.0 of c/
 {5.0 of C/ (1.28)}
 (0.50)}
 8 1.0 of B/ 0.04 of a/ 0.2 of b/ 0.03 of U/ b 4.0
 (0.05) (0.03) (0.06) (0.03)
 9 2.0 of A/ 0.5 of a/ 2.0 of A/ 3.00 of Z/ a 1.6
 (0.23) (0.41) (0.56) (0.15)
 TABLE 3
 COMPOSITIONS OF SURFACE TREATMENT BATHS FOR COMISON
 EXAMPLES 1 TO 5
 Compar- Grams per Liter in Bath of:
 ison Ti Com- Phosphate Fluoride Accelerator pH pH
 Example pound/ Source/ Source/ Source/(Active Regulator of
 Number (Ti) (PO.sub.4.sup.-3) (F) Accelerator) Type
 Bath
 1 none 1.0 of a/ 0.5 of b/ 1.00 of V/ a 1.3
 (0.82) (0.16) (0.97)
 2 5.0 of A/ none 5.0 of A/ 0.30 of W/ b 1.6
 (0.58) (1.39) (0.27)
 3 10.0 of C/ 1.5 of a/ none 1.0 of Y/ a 1.2
 (1.00) (1.24) (0.69)
 4 30.0 of B/ 4.0 of a/ 5.0 of a/ 0.5 of V/ b 5.0
 (1.44) (3.30) (0.95) (0.49)
 5 10.0 of B/ 1.0 of a/ 5.0 of a/ none b 1.5
 (0.48) (0.82) (0.95)
 TABLE 4
 PROCESS CONDITIONS AND EVALUATION TEST RESULTS
 Conditions During
 Example Treatment According
 ("Ex") or to the Invention or
 Comparison Comparison Rating
 Example Contact Add-on after 150 Paint Adherence,
 ("CE") Temper- Time, Mass of Hour Salt kgf/10 mm of Width
 Number ature, .degree. C. Seconds Ti, mg/m.sup.2 Spray Test
 Primary Secondary
 Ex 1 40 6 15 +++ 10.8 8.3
 Ex 2 45 40 20 +++ 9.4 6.7
 Ex 3 40 5 12 +++ 9.0 6.7
 Ex 4 65 2 15 +++ 11.4 9.2
 Ex 5 35 5 4.5 +++ 10.5 9.0
 Ex 6 45 8 43 +++ 9.3 6.8
 Ex 7 60 4 25 +++ 8.9 7.8
 Ex 8 35 50 9.0 +++ 7.5 5.3
 Ex 9 50 12 20 +++ 7.2 5.5
 CE 1 50 10 0 .times. 3.8 1.0
 CE 2 55 5 20 + 6.0 2.9
 CE 3 35 40 1.0 .times. 4.0 1.3
 CE 4 45 8 17 ++ 5.2 3.4
 CE 5 60 30 2.0 .times. 5.0 1.3
 CE 6 40 30 *18 of Zr ++ 7.2 5.0
 CE 7 40 5 *5 of Zr + 4.6 2.7
 Footnote for Table 4
 *There is no titanium added in these comparison examples, which used a
 treatment composition that does not contain titanium.