CA2208459A1 - Low sludging composition and process for treating aluminum and its alloys - Google Patents
Low sludging composition and process for treating aluminum and its alloysInfo
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- CA2208459A1 CA2208459A1 CA 2208459 CA2208459A CA2208459A1 CA 2208459 A1 CA2208459 A1 CA 2208459A1 CA 2208459 CA2208459 CA 2208459 CA 2208459 A CA2208459 A CA 2208459A CA 2208459 A1 CA2208459 A1 CA 2208459A1
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- aqueous liquid
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
- C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
- C23C22/361—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing titanium, zirconium or hafnium compounds
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- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
Abstract
A highly corrosion-resistant, strongly paint-adherent conversion coating is formed on the surface of aluminiferous metal substrates by contacting such surfaces for 0.5 to 60 seconds with a sludging-free water-based surface treatment bath that has a pH of 1.5 to 4.0 and contains a zirconium compound, phosphoric acid compound, oxidizing agent, and a compound that is a source of hydrogen fluoride (in a quantity that produces a concentration of from 0.0001 to 0.2 g/L HF in the treatment bath). This contact is preferably followed by a water rinse and drying.
Description
CA 022084~9 1997-06-20 W O96/l9S95 PCTnUS95/16231 Desc, ipLio LOW SLUDGING COMPOSITION AND PROCESS FOR TREATING ALUMINUM
AND ITS ALLOYS
Technical Field This invention relates to a surface l, eat" lenl co" ,posilion and prc,cess thatform a conversion coating on the surface of al-" ni~ lirer~us metals that impa, ls an excellent CGI I OSiOI I resislance and paint adl ,erence to such surfaces prior to their 5 painting. The aqueous solutions of this composilion are transparent solutions that resist the production of a precipitating solid even when they contain eluted aluminum. The present invention is applied with particularly good effect to the surface treatment of drawn-and-ironed aluminum cans (hereinafter usually abbreviated as "aluminum Dl cans"). Sludge adhesion to the equipment is 10 inl ~ibiled and an ~Yc~llent corrosion ~esislance and paint adherence are imparted to the subsl,ale surface when aluminum Dl cans fabricated by the drawing and ironing of aluminum alloy sheets are subjected prior to their being painted and/or printed to surface treatment with a surface treatment bath according to the present invention.
Background Art The outside bottom surface of aluminum Dl cans is subjected to high-tem-perature sterilization without being painted. If this region has a low corrosionresistance the aluminum is oxidized and blackened during this step and its appearance is thereby impaired. This phenomenon is generally known as "blackening". As a result the (unpainted) conversion coating produced by sur-face treal",enl desirably should have an intrinsically high corrosion resistance.
At thé present time the surface treatment of aluminum Dl cans is carried out mainly using Cr(VI)-containing phosphoric acid-chromate treatments and zirconium-type nonchromate treatments. These treatments are applied to the surfaces of the cans as aqueous liquid compositions which hereinafter are us-ually called "baths" for brevity even though they are more often applied by spray-ing the "bath" liquid onto cans than by immersion of the cans in the baths.
A typical example of nonch,un,ale surface treatment baths is disclosed in W Og6119S95 PCTnUS95116231 . Japa, lese Patent Publication Number Sho ~6-33468 [33,468/1981]. This surface treatment bath is an acidic (pH 1.5 to 4.0) water-based coating solution that contains phosphate, fluoride, and zirconium or titanium or a mixture thereof.
The chara~,~ri~lic features of this acidic nonchromale treatment bath are that it contains effective fluoride and does not contain a solid-producing com-ponent that is prone to precipitation. Since this non.;l)ro"~ate treatment bath does not co, llai.l toxic hexavalent chromium, it has come to be widely used at the present time as a surface l,eal",e"l agent for aluminum Dl cans. However, this bath in ~ctu~lity also suffers from major drawbacks as described in the following.
.0 When the prior art surface treatment baths are used on can manufacturing lines, they are ordinarily sprayed on the aluminum Dl cans for about 15 to 30 seconds. When an object shaped like aluminum Dl cans is subjected to spray treatment for such a brief period of time, the resulting coating may not be uniform, bet~use of differences that occur between different regions of the can in the bath flow rate and in the conlacL conditions between the bath and the surface of the substrate. This creates variations or instabilities in the anticor-rosion perforrnance.
If, however, the production of a large conversion coating weight on the outside bottom surface of the can is pursued in order to stabilize the anticorro-sion pe~ rO" "a"ce, too much conversion coaliny will be produced on the neckingor flange regions that are processed after painting. This causes the problem of paint delamination after painting.
This variation in coali"g weight among the crorel "enlio"ed regions is everi more sl~hst~rltial in the case of aged surface treatment baths where the ac-cumulated concentration of eluted aluminum in the solution has reached highvalues.
When the dro, e,nen~iol ,ed prior art surface treatment bath is used industri-ally, avoiding ~" lacce,uLable paint delamination results in the major drawback of ~ requiring the use of an effective fluoride concenbdlion, which essentially must be 30 maintained at a co"sLa~ ll value during use of the bath, that is somewhat smaller than that which would be most desirable for avoiding blackening and avoiding theror"~aLion of precipitates.
CA 022084~9 l997-06-20 - Due to this, when aluminum ions actually do elute and enter the bath, pre-cipitation occurs even for the above-described surface l,eal",e"l bath with its distinguishing feature of not containing a highly precipitation-prone solid-pro-ducing component. Even with this bath, then, problems such as equip",e"l soiling, nozle clogging, and the like, do in fact occur.
Disclosure of the Invention Problems to Be Solved by the Invention The present invention seeks to solve the problems described above for the prior art. In specific terms, the pr~senl invention introduces a bath and a pro-10 cess using said bath that not only are able to produce a highly corrosion-re-sistant, strongly paint-adherent conversion coating on the surfaces of alumin-iferous metal substrates, but which also exhibit excellent properties in terms of conversion coating uniformity, sludging inhibition, and process stability.
Summary of the Invention It has been discovered that:
(i) a treatment bath that maintains a ll a"spar~, ll appea(dl Ice can be obtained when an oxidizing agent and a hydrogen fluoride-generating compound that produces a particular value for the HF concenl, alion are also present in a surface treatment bath that contains a phosphoric acid compound and zirconium compound and has a pH of 1.5 to 4.0;
(ii) an excellent corrosion resistance and good paint adherence can be imparted to the surface of aluminiferous metal substrates by the formation thereon of a conversion coating by contacting the surface of the aluminiferous metal with the aforesaid conversion bath for 0.5 to 60 seconds; and (iii) the conversion coali"g thereby formed is very uniform, while at the same time an excellent sludging inhibition is obtained.
The highly sludging-i,lhibiled coll~rosiliol1 according to the present inven-tion for treating the surface of aluminiferous metals is a waterborne surface lreal",e"l bath that forms a conversion coating on the surface of aluminiferous metals and is chara~leri~ed in that it has a pH of 1.5 to 4.0 and comprises, pref-erably consists essentially of, or more pre~erably consists of water and the fol-lowing components:
CA 022084~9 1997-06-20 W O96/l9S95 PCTnUS95/16231 (A) at least one phosphoric acid compound (B) at least one zirconium compound, (C) at least one oxidizing agent and (D) at least one co" ,pound that is a source of hydrogen fluoride in a quantity that produces a total concer,l,dlion of hydrogen fluoride in the aqueous solution in the range from 0.0001 to 0.2 grams per liter (hereinafter us-ually abbreviated as "g/L ).
Detailed Desc,i,~.lion of the Invention and P~erer,ed Embodiments Thereof The aforesaid hydluye" fluoride-generating compound in the surface ~o treatment com~.osilio~ I accûrding to the present invention is preferably selected from hydrofluoric acid and ammonium fluoride.
The aforesaid o,(idi~i"g agent in the surface treatment composition accor-ding to the present invention preferably consists of at least one selection fromhydrogen peroxide nitrous acid organoperoxides and salts of the preceding.
The aroresaid zirconium compound(s) are ~rererably present in a surface treatment co, nposilion according to the present invention at a total conce"l, alion of 0.005 to 0.5 g/L as zirconium.
The droresaid p hospl ,oric acid compound(s) is prererably present in a sur-face l, e~L" ,enl co m posilion acco, di"g to the present invention at a concentration of 0.005 to 0.4 g/L as PO4-3 ions. The total stoichiometric equivalent as POj3 ions of all orthophosphoric acid (i.e. H3PO4) metaphosphoric acids (i.e.
[HPO3~X where x is a positive integer with a value of at least 3) and condensed phos~cl ,oric acids (i.e. H(n+2)PnOt3"~,p where n is a positive integer with a value of at least 2) and any anionic products formed by dissoci~ion of any of these acidsincluding such anions added to the composition in the form of salts is to be understood as constituting the Poi3 ions corllellt for the definition of this concer,l,dlion i"es,uec~ e of the actual extent of ionization dissociation and/or .ssoci~tion that may occur in the surface treatment composition.
The aforesaid oxidizing agent is preferably present in the surface treatment composition according to the present invention at a concentration of 0.01 to 5.0 g/L.
A highly sludging-inhibited p,ocess accor~li"g to the present invention for CA 022084~9 1997-06-20 W O96119S9S PCTnUS9S/16231 treating the surface of al~ ,irerous metal suL~sl~ales is characteri~ed by the ror",dlion of a conversion coating on the surface of aluminiferous metal by con-tacting said surface for 0.5 to 60 seconds with a treatment bath containing any surface l,eal",enl composition as described directly above and there~rler, optionally, subjecting said surface to a water rinse and drying.
When prior art surface ll eat" ,enl agents with their relatively slow reaction rates are sprayed on an article shaped like aluminum Dl cans, the resulting conversion coating usually will not be uniform, because of dirrere"ces in bath flow rate and surface/bath contact conditions that occur between different ~o regions. The conversion coatiny may therefore exhibit an uneven performance.
In the specific case of aged surface treatment solutions in which the aluminum ions cGncenlrdlion in the solution has reached high levels, fluorine is consumedfrom the fluorocor"plex of zirconium and it becomes necess~ry to add additional fluorine source in order to keep the zirconium stably dissolved in the bath, i.e., to keep the treatment bath transparent. This c~uses an even more pronounced variation in coating weight among the various regions of the can.
The inventors discovered that the rate of the conversion coating formation reactions and the ~" lirul " ,ily of the conversion coating can be improved through the presence of HF--in addition to zirconium, phosphoric acid, and oxidizing agent--for the purpose of slabili~i"g the quality by eliminating the variations in coating weight between the regions of such a shaped article that would otherwisearise from differences in reaction rate.
It was also discovered that managing the HF concentration to 0.0001 to 0.2 g/L in order to inhibit pr~c;,.~ilatiol) of the zirconium in the treatment bath leads to an improved inhibition of sludge ro~",alio,) even in the case of aged treatment baths having high aluminum ion concentrations.
Coating formation is believed to occur during treatment with a zirconium-~nlail lil ,g treatment bath bec~l Ise of an i"~ ease in pH at the interface between the metal substrate and the treatment bath. On the other hand, with regard to 30 the hydrofluoric acid and aluminum fluorocomplexes present in conversion l,edl",enl baths, it is known that the structures of these compounds change as a function of the pH of the treatment bath. Free fluoride (F-), hydrofluoric acid CA 022084~9 l997-06-20 W O96/19S95 PCTrUS95/16231 (HF), and various aluminum fluorocomplexes may be present in an acidic ~ql leo~ 's solution containing aluminum and fluorine. Their proportions vary with variations in the pH of the ~q~eo~ls solution. Conversion coating formation reactions are believed to occur due to the decline in the HF conce"l, dlion in the vicinity of the inle,race. Thererore, control of the HF concentration in the l,edl"~enl bath becomes necess~y in orderto l"ailllain a high conversion activity and a transparent appearance on the part of the treatment bath.
The HF concer,lr~lion is measured in the present invention as follows. A
corn~"el~,ially available fluoride ion reference solution is first diluted with a com-mercially available solution for adjusting the pH/ionic strength, in order to prepare three rerere"ce solutions with the following F- concentrations: F- = 1 mg/L, F- =
10 mg/L, and F- = 100 mg/L. These are then equilibrated at the specified temperature and used to calibrate the measurement values of a fluoride ion meter. A sample of the surface treatment solution is then equilibrated at the specified temperature, and its F- concer,l, ;alion is obtained using the calibrated fluorine ion meter and converted to the molar concenl, clion, designated as "[F-]".
The pH of the treatment bath is also measured and the molar H+ concentration, designated as "[H']", is derived from this. The molar conceniralion of HF, desiyndled as "[HF]", is then calculated from the known dissociation constant for HF according to the following equation: [HF] = {~H+] ~ [Fl/10-3'7}. The lHF] value thus obtained is converted to g/L by multiplying by the gram molecular weight ofHF.
The following concel,l,alions are preferred for the surface treatment composition accordil-g to the present invention: for the zirconium compound, 0.005 to 0.5 g/L as zirconium; for the phosphoric acid compound, 0.005 to 0.4 g/L as PO4 ions; for the oxidizing agent, 0.01 to 5 g/L.
With regard to the concenll alions of the phosphoric acid compound, zir-conium cor"pound, and oxidi~ing agent in the surface treatment composition ac-cordir,g to the present invention, if any of these falls below the above-specified lower limits, the resulting treatment bath will have an inadequate conversion coali"g formation activity and may not be able to lay down a conversion coating of sufficient thickness. No additional increases in effect are obtained when these CA 022084~9 1997-06-20 W O 96119S9S P~1-IU~I16231 conce, Itrations e~ eed the above-speciried upper limits, and such conce"lralions therefore serve merely to raise the cost.
Zirconium-containing sludge is readily produced when the concentration of the hy.l~oge~, fluoride-source compound in the surface treatment composition ' 5 according to the present invention falls below 0.0001 g/L as HF (hydrogen fluoride). An excessive etch, which impedes the for",alion of a conversion coating, occurs when this value exceeds 0.2 g/L.
A surface treatment process acco,.liny to the ~,rese,)l invention comprises the formation of a conversion coating by bringing the target surface of the aluminiferous metal sul.stlale into conlac~ with a treatment bath containing treat-ment co",posilion as described above and then, optionally but preferably, exe-cuting thereon a water rinse and drying. Said contact between the treatment bath and metal surface may be implemented, using spray or immersion tech-nology, as a continuous one-step process or as an intermittent multi-step pro-~5 cess. The total conla~;t time preferably should be from 0.~ to 60 seconds.
BeG~ se the specific component composition of the treatment bath is able to in-hibit sludge adhesion to the equipment, the described process according to the present invention can achieve an excellent operating stability and a high treat-ment efficiency.
The surface treatment bath according to the present invention is an acidic treatment bath that contains phosphate ions, a zirconium compound, fluoride, and oxidi~i"g agent as its essential components. The source of the phosphate ions in this ~, edl,l)el)l bath prererably is phosphoric acid, ammonium phosphate, and/or an alkali metal salt of phosphoric acid, with phosphoric acid and 25 ammonium phosphate more preferred, taking into consideration sludging inhibition. The content is preferably 0.005 to 0.4 g/L as phosphate (PO4) ions, while the range of 0.01 to 0.20 g/L as phosphate ion is even more preferred.
P hos,cl ,dle ion concerlt, dlions below 0.005 g/L result in a poor reactivity, which makes it very difficult to form satisraclo"/ coalings. At the other extreme, no -30 additional benefits are obtained at cor,ce,)lralions in excess of 0.4 g/L, which thererore serve merely to raise the cost of the treatment bath and thus are eco-nomically undesirable.
CA 022084~9 1997-06-20 W O96/195g5 PCTnUS9S/16231 The presence of a zirconium compound in treatment baths according to the pr~senl invention is most advantageously brought about through the use of water-soluble col npounds of zirconium more preferably water-soluble fluorozir-conium complexes and still more ,l~referably fluo~i,co"ic acid (H2ZrF6) and its salts. With regard to the use of the oxide hydroxide nitrate or phosphate of zir-conium this should be acco",,l~anied by the simultaneous addiliol, of fluoride that fu, nishes hydrogen fluoride in sufficient quantity to transform the zirconium into a water-soluble fluorocomplex and thereby prevent production of a precipitate.
The ,i, ~".um c~mpound conlenl is ,c rerer~bly 0.005 to 0.5 g/L as zirconium andis more l~r~rerably 0.01 to 0.1 g/L as zirconium. Adequate film formation may not occur at a zirconium conlent below 0.005 g/L. No additional benefits are obtained at conce"l, dlions in excess of 0.5 g/L which therefore serve merely toraise the cost of the treatment bath and thus are economically undesirable.
The presence of h~dl ~gen fluoride in the treatment bath according to the ,~resel ,l invention is most adva"lageously brought about by adding hydrofluoricacid or al~ ,monium fluoride. The prt:rel l~cl HF conlenl falls in the range of 0.0001 to 0.2 g/L and more preferably falls in the range of 0.01 to 0.1 g/L.
The oxidizing agent present in the treatment bath acco, .3i"g to the present invention is exemplified by hydrogen peroxide nitrous acid and its salts and or-20 ganoperoxides. The use of hydrogen peroxide is most preferred based on aconsideration of the ease of treating the waste water produced by the process accor.ling to the present invention. The oxidizing agent functions to acceleratethe rate of the reacLions that produce the zirconium coating. The oxidizing agent content is preferably 0.01 to 5 g/L and more prerelably 0.1 to 1.0 g/L. The reaction-accelerating activity may be unsatisfactory at oxidizing agent concer,l, dlio,-s below 0.01 g/L. No problems are associated with concentrationsin excess of 5 g/L but such concer,l,aLions do not provide any additional benefit and thus merely drive up the costs and are therefore economically undesirable.
The pH of the l, eal, nenl bath should be adjusted to 1.5 to 4Ø The extent 30 of etching becomes excessive at pH values below 1.5 and impedes conversion coating formation. The etch becomes too weak at pH values in excess of 4.0 and makes it dfflicult to form a highly corrosion-resistant coating. The preferred CA 022084~9 l997-06-20 WO 96/lg59S PCI/US95/16231 pH range is 2.3 to 3Ø The pH can be adjusted through the use of an acid such as phosphoric acid, nitric acid, or hydrochloric acid, or through the use of an alkali such as ammonium h~dloxide, a""~onium cd,l,onale, or sodium hydroxide.
rhospl ,o, ic acid and nitric acid are the prere" ed acids for adjusting the pH, while ,~ 5 basic ammo,-ium compounds are prefer,ed as the alkali.
The stability of the l,e~",enl bath can be substantially impaired by metal ions, such as those of copper, mdnydnese, and the like, that are produced when an alloying co",pol.ent is eluted from the surface of the aluminiferous metal substrate. This can result in such problems as sludge production, precipitate formation, and the adhesion of sludge and/or precipitate to the equipment and the like. In order to prevent this from happening, an organic acid or salt thereof, for exdr"ple, gluconic acid, oxalic acid, and their salts, may be added in order to chelate such components and stabilize the bath.
A water-soluble fluoroco",plex of, for example, titanium, silicon, and the like, may also be added to the surface treatment bath according to the present invention along with the zirconium compound, for example, a water-soluble fluoro~i,conium complex.
An example of the surface treatment process according to the present invention for an aluminiferous metal substrate includes the following steps:
20 (1) surface cleaning: degreasing (acidic, alkaline, or solvent-based degreasers may be used) (2) water rinse (3) conversion coating treatment (surface treatment using a treatment bath according to the present invention) (4) water rinse (5) rinse with deionized water (6) drying The treatment temperature with the surface treatment bath acco~ ,9 to the presenl invention is not crucial, and, for example, a temperature range from- roorrl temperature to 90 ~C can be used. However, taking into consideration the stability, operating behavior, and productivity characteristics of the treatmentbath, the bath is preferably used at from 25 ~C to 50 ~C. The treatment time is CA 022084~9 1997-06-20 W O96/lgS9S PCTnUS95/16231 also not crucial but treatment times of for example 0.5 to 60 seconds are preferred and the range of 5 to 30 seconds is even more preferred. A full reaction is not usually ~btail ,ed in less than 5 seconds; this would prevent the ro"n~lion of a highly corrosion-resistant coating. At the other end of the rangeno additional increase in pe,ro""a"ce has been observed at times above 60 seconds.
The surface treatment bath and process according to the present inven-tion will be illustrated through the working examples provided below.
Exalll~,lcs The following sam,~!es and pe,~n,lance evaluation tests were used in the working and cor"parali,le examples.
(1 ) Samples The materials were aluminum alloy (A3004) sheets and aluminum Dl cans fabricated from this type of aluminum alloy sheet. These were each cleaned prior to surface ll eal" ,enl according to this invention with a hot aqueous solution of an acidic degreaser (PALKLINTM 500 a product of Nihon Parkerizing Company Limited Tokyo).
(2) Evaluation methods (a) Corrosion resistance and coating uniformity The corrosion resistance and coating uniformity were evaluated on the aluminum Dl cans based on the resistance to blackening by boiling water. The resistance to blackening by boiling water was tested as follows. After surface l, eal" ,enl the aluminum Dl cans were immersed in boiling tap water for 30 min-utes This was followed by a visual deler",ir,ation of the degree of discoloration (blackening) thereby prorll Iced at the elevations (regio"s where the bath flow rate was fast) and depression (region where the bath flow rate was slow) of the aluminum Dl cans. Said elevations correspond to the rib and exterior sidewall regions of actual aluminum Dl cans while the depression corresponds to the dome reglon.
The corrosion resistance was evaluated by scoring the test results on the following scale:
+ = noblackening CA 022084~9 l997-06-20 W O96/1gS95 PCTnUS95/1623 = blackening over part of the suRace x = blackening over the entire surface.
The codlil~g ~" ~irur,,,ily was rated as follows based on the resulting loca-tion-specific ev~ tion of the r~sislance to blackening by boiling water: a scores of "~" ,irc,r"~" was render~d when both locations were free of blackening, while a score of "nonuniform" was rendered when blackening occurred at only one location.
(b) Paint adl ,erence After the aluminum alloy (A30f~4) sheet had been subjected to the suRace ~o treatment, it was coated with a can-grade epoxy-urea paint to give a paint film thickness of 5 to 7 micfo",eters. This was followed by baking and drying to givea painted panel. A test panel was then prepared by bending the painted panel in a bending tester, and this test panel was subjected to a peel test using cellophane tape. The test results were scored as follows:
+ = peeling did not occur x = peeling occurred.
Bath transparency The treal"~enl bath which had been used in the particular example or con,pardli~/e example was held at 40 ~C for 1~ days. The amount of zirconium in the bath was measured both before and after this holding period, and the presence/absence of precipitate was determined from the difference in these values. A "+" indicates that prec;~,ilale was not producerl while "x" indicates that precipitate was produced.
~ Confirming test for sludge adhesion The treatment bath which had been used in the particular example or co" ~par~ /e example was supplied continuously for 16 hours to spray treatment using a small-scale sprayer held at 40 ~C. During this time, the development of sludge at the nozle of the device was inspected visually. A "+" indicates no - sludge adhesion, while "x" indicates that sludge adhesion occurred.
Example 1 The c;ea,led aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 20 seconds with suRace treatment bath (1) (composition given W O96/lgS95 PCTnUS9~/16231 below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The sa" I,~les thus obtained were evaluated for their corrosion resistance, codling uniformity, and paint adherence.
The aluminum nitrate was used as an aluminum source for the purpose of artificially aging the treatment bath.
Surface treatment bath (1 ) phosphoric acid 30 ppm as P04 ions fluo,ilconic acid 30 ppm as Zr hydrogen peroxide 100 ppm as H202 aluminum nitrate 100 ppm asAI
pH - 3.0 (adjusted with aqueous ammonia) conce"lralion of HF = 11 ppm (adjusted with hydrofluoric acid).
Example 2 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 40 seconds with surface treatment bath (2) (composition given below) heated to 40 ~C~ This was followed by rinsing with tap water, spray rins-ing for 10 second~ with deioni~ed water, and then drying in a hot-air dr,ving oven.
The samples thus oblained were ev~ tP, :I for their corrosion resistance, coating uniformity, and paint adherence.
Surface treatment bath (2) phospl1oric acid 20 ppm as P04 ions fluo~irco,1ic acid 10 ppm as Zr hydrogen peroxide 300 ppm as H2O2 aluminum nitrate 50 ppm as Al pH = 2.7 (a~justed with aqueous al~ OI ,ia) conce"ll dlion of HF = 9 ppm (adjusted with hydrofluoric acid) Example 3 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 15 seconds with surface treatment bath (3) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air drying CA 022084~9 1997-06-20 W Og6119Sg5 1~1/~',5/16231 oven. The Sdl nples thus obtained were ev~ t~:I for their corrosion resistance coating uniformity and paint adherence.
Surface treatment bath (3) phosphoric acid 40 ppm as PO4 ions ,~ 5 fluo~i~onic acid 40 ppm as Zr hydrugenperoxide 200 ppm as H2O
aluminum nitrate 200 ppm as Al pH = 2.3 (adjusted with aqueous ar"r"ûr,ia) concentration of HF = 15 ppm (adjusted with hydrofluoric acid) ,0 Example 4 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were immersed for 10 seconds in surface l,edt",enl bath (4) (composition given below)heated to 30 ~C. This was followed by rinsing with tap water spray rinsing for 10 seconds with deionized water! and then drying in a hot-air drying oven. The 5 samples thus obtained were evaluated for their corrosion resistance coating uniformity and paint adherence.
Surface treatment bath (4) phosphoricacid 150 ppm as PO4 ions fluozirconic acid 100 ppm as Zr hydrogen peroxide 400 ppm as H2O2 aluminum nitrate 300 ppm as Al pH = 2.5 (adjusted with aqueous ammonia) concentration of HF = 70 ppm (adjusted with hydrofluoric acid) Example 5 The claaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 5 secon ds with surface l,eal",e, ll bath (5) (composition given below) heated to 30 ~C. This was followed by rinsing with tap water spray rinsing for 10 seconds with deionized water and then drying in a hot-air drying oven. The samples thus obtained were evaluated for their corrosion resistance coating uniformity and paint adherence.
CA 022084~9 1997-06-20 W O96/19S9S PCTrUS95/16231 Surface treatment bath (5) phosphoric acid 400 ppm as P04 ions ammonium fluo,ircGnate 200 ppm as Zr hydrogen peroxide 500 ppm as H2O2 aluminum nitrate 500 ppm as Al pH = 2.5 (adjusted with aqueous ammonia) conce"l,alion of HF = 100 ppm (adjusted with hydrofluoric acid).
Example 6 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were o sprayed for 15 seconds with surface treatment bath (6) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seco, Icls with deionized water, and then drying in a hot-air drying oven.
The samples thus obtained were ev~ ted for their corrosion resi~lance, coating uniformity, and paint adherence.
Surface treatment bath (6) phosphoricacid 50 ppm as PO4ions zirconium oxide 30 ppm as Zr hydrogen peroxide 200ppm as H2O2 aluminum nitrate 200 ppm as Al pH = 2.3 (adjusted with aqueous ammonia) concentration of HF = 13 ppm (adjusted with hydrofluoric acid) Example 7 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 15 seconds with surface treatment bath (7) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seconds with deionized water, ar~d then drying in a hot-air drying oven.
The samples thus obtained were ev~ ted for their corrosion resislance, coating uniformity, and paint adherence.
Surface treatment bath (7) phosphoric acid 50 ppm as P O4 ions r zirconium oxide 30 ppm as Zr hydrogen peroxide 200 ppm as H2O2 CA 022084~9 l997-06-20 W Og6/l9S9S PCTnUS95/16231 aluminum nitrate 100 ppm as Al pH = 3.5 (adjusted with ~s~ueous am~,onia) concerlL, dlion of HF = 7 ppm (adjusted with hydrofluoric acid).
Compalalive Example 1 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 10 seconds with surface treatment bath (8) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The sa~ )'es thus obtained were evaluated for their corrosion resistance, .0 coaling uniformity, and paint adherence.
Surface l~eal~,enl bath (8) (no oxidizing agent) phosphoricacid 30ppm as PO4 ions fluo~ircGnic acid 30 ppm as Zr aluminum nitrate 200 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) conce"l, dlion of HF = 15 ppm (~ sted with hydrofluoric acid).
Comparative Example 2 The claal1ed aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 10 seconds with surface l,eal",ent bath (9) (composition given below) heated to 50 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seconds with deionized water, and then drying in a hot-air drying oven.
The samples thus obtained were evaluated for their corrosion resisla"ce, coatinguniformity, and paint adherence.
Surface treatment bath (9) (no zirconium compound) phosphoricacid 50 ppm as PO4ions hydrofluoricacid 220ppm as F
hydrogen peroxide 500 ppm as H2O2 aluminum nitrate 100 ppm asAI
pH = 2.5 (adjusted with aqueous al"",o"ia) concentration of HF = 10 ppm (adjusted with hydrofluoric acid) Comparative Example 3 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were CA 022084~9 1997-06-20 W O96/l9S95 PCTnUS95116231 sprayed for 20 seconds with surface treatment bath (10) (composition given below) heated to 35 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The samples thus obtained were evaluated for their corrosion resistance, 5 coating uniformity, and paint adherence.
Surface l,eal",e"t bath (10) fluo~irco~,ic acid 40 ppm as Zr hydrogen peroxide 500 ppm as H2O2 aluminum nitrate 200 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) concentration of HF = 50 ppm (adjusted with hydrofluoric acid).
Comparative Example 4 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 15 seconds with surface treatment bath (11) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The sarnples thus oblai"ed were evaluated for their corrosion resistance, coating uniformity, and paint adherence.
Surface treatment bath (11 ) 20 phosphoric acid 50 ppm as P04 ions fluozirconic acid 50 ppm as Zr hydrogen peroxide 300 ppm as H202 aluminum nitrate 200 ppm as Al pH = 2.7 (adjusted with aqueous ammonia) concnetration of HF = 0.05 ppm (adjusted with hydrofluoric acid).
Comparative Example 5 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 10 seconds with surface treatment bath (12) (composition given . below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-30 ing for 10 seconds with ~Jeior,i~ed water, and then drying in a hot-air drying oven.
The san ~ les thus oL)lained were evaluated for their co~ I osio, I resi~la~ ~ce, coating uniformity, and paint adherence.
CA 022084~9 1997-06-20 WO g6/lg5gS PCI/US95/16231 Surface treatment bath (12) ,uhospl ,oric acid 40 ppm as PO4 ions zirconium oxide 40 ppm as Zr hydrogen peroxide 300ppm as H2O2 ,~ 5 aluminum nitrate 200 ppm as Al pH = 2.8 (adjusted with aqueous ammonia) conce"Lrdlion of HF = 0.01 ppm (adjusted with hydrofluoric acid).
GGr"parali~/e Example 6 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were 10 sprayed for 15 seconds with surface treatment bath (13) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The samples thus obtained were evaluated for their corrosion resistance, coating uniformity, and paint adherence.
Surface lledlll~enl bath (13) phosphoricacid 40ppm as PO4 ions fluo~irconic acid 40 ppm as Zr aluminum nitrate 300 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) conce"l, alion of HF = 15 ppm (adjusted with hydrofluoric acid).
Comparative Example 7 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 30 seconds with surface treatment bath (14) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seconds with CieiOI ,i~ed water, and then drying in a hot-air drying oven.
The samples thus oblai. ,ed were evaluated for their corrosion r esisla,)ce, coating uniformity, and paint adherence.
SurFace treatment bath (14) phosphoric acid 100 ppm as PO4 ions fluo~ircol ,ic acid 100 ppm as Zr aluminum nitrate 300 ppm as Al pH = 3.0 (adjusted with aqueous am~onia) W O 96/19S9S PCTrUS9~/16231 co"cenl~dlio" of HF = 20 ppm (adjusted with hydrofluoric acid).
Test results from all the Examples and Co",pa,dli~/e examples are report-ed in Table 1.
Exa"~ples 1 to 7 used surface L,eat"~e,ll baths and surface treatment pro-cesses accordi"g to the present invention and Table 1 col,ri~",s the followingresults for these examples: the obtained conversion coatings exhibited an excellent corrosion resistance and paint adherence; the obtained conversion codlings were very uniform; the surface treatment baths maintained their trans-parency; and sludge adhesion was thoroughly inhibited. In contrast Com-10 parative Examples 1 to 7--which used surface treatment baths outside thescope of the invention--in each case gave an unsatisfactory overall perform-ance because each was found to be deficient in at least one aspect (corrosion resistance paint adherence conversion coating uniformity treatment bath transparency and inhibition of sludge adhesion).
The surFace lreal" ~enl con,position and surface treatment process accord-ing to the presenl invention impart an excellent corrosion resistance and ex-cellent paint a.lher~nce to the surface of aluminiferous metal substrates prior to the painting thereof. Other desirable effects demonstrated by this composition and process are a very uniform conversion coating excellent treatment bath transparency and an excellent inhibition of sludge adhesion.
These ~arac~ri~lics confer a high degree of practical utility on the bath and prucess accor~i"g to the present invention for treating the surface of alumin-iferous metal suL,~lrales.
W Og6/19SgS PCTnUS95/16231 E~ample Corrosion Resistanceand Uniformity Paint Bath Inhibition or Com- Adher- Trans- of Sludge parison Elevations Depressions Uniformity ence parency Adhesion Example Ex 1 + + .. ,,;ru..... + + +
Ex 2 + + uniform + + +
Ex3 + + uniform + + +
Ex 4 + + ~II.ir~ + + +
Ex 5 + +~ ;ru~ .... + + +
Ex 6 + + ulfirulln + + +
Ex 7 + + ullirullll + + +
CE 1 x x - + + +
CE2 x x - + + +
CE3 x x - + + +
CE 4 + + uniforrn + x x CE 5 x (~nomlniform + x x CE6 x . + nonuniforrn + + +
CE 7 (~ + nonuniforrn x + +
Abbreviations for Table 1 "Ex" = "Example"; "CE" = "Colllp~ re Fx~ ple".
AND ITS ALLOYS
Technical Field This invention relates to a surface l, eat" lenl co" ,posilion and prc,cess thatform a conversion coating on the surface of al-" ni~ lirer~us metals that impa, ls an excellent CGI I OSiOI I resislance and paint adl ,erence to such surfaces prior to their 5 painting. The aqueous solutions of this composilion are transparent solutions that resist the production of a precipitating solid even when they contain eluted aluminum. The present invention is applied with particularly good effect to the surface treatment of drawn-and-ironed aluminum cans (hereinafter usually abbreviated as "aluminum Dl cans"). Sludge adhesion to the equipment is 10 inl ~ibiled and an ~Yc~llent corrosion ~esislance and paint adherence are imparted to the subsl,ale surface when aluminum Dl cans fabricated by the drawing and ironing of aluminum alloy sheets are subjected prior to their being painted and/or printed to surface treatment with a surface treatment bath according to the present invention.
Background Art The outside bottom surface of aluminum Dl cans is subjected to high-tem-perature sterilization without being painted. If this region has a low corrosionresistance the aluminum is oxidized and blackened during this step and its appearance is thereby impaired. This phenomenon is generally known as "blackening". As a result the (unpainted) conversion coating produced by sur-face treal",enl desirably should have an intrinsically high corrosion resistance.
At thé present time the surface treatment of aluminum Dl cans is carried out mainly using Cr(VI)-containing phosphoric acid-chromate treatments and zirconium-type nonchromate treatments. These treatments are applied to the surfaces of the cans as aqueous liquid compositions which hereinafter are us-ually called "baths" for brevity even though they are more often applied by spray-ing the "bath" liquid onto cans than by immersion of the cans in the baths.
A typical example of nonch,un,ale surface treatment baths is disclosed in W Og6119S95 PCTnUS95116231 . Japa, lese Patent Publication Number Sho ~6-33468 [33,468/1981]. This surface treatment bath is an acidic (pH 1.5 to 4.0) water-based coating solution that contains phosphate, fluoride, and zirconium or titanium or a mixture thereof.
The chara~,~ri~lic features of this acidic nonchromale treatment bath are that it contains effective fluoride and does not contain a solid-producing com-ponent that is prone to precipitation. Since this non.;l)ro"~ate treatment bath does not co, llai.l toxic hexavalent chromium, it has come to be widely used at the present time as a surface l,eal",e"l agent for aluminum Dl cans. However, this bath in ~ctu~lity also suffers from major drawbacks as described in the following.
.0 When the prior art surface treatment baths are used on can manufacturing lines, they are ordinarily sprayed on the aluminum Dl cans for about 15 to 30 seconds. When an object shaped like aluminum Dl cans is subjected to spray treatment for such a brief period of time, the resulting coating may not be uniform, bet~use of differences that occur between different regions of the can in the bath flow rate and in the conlacL conditions between the bath and the surface of the substrate. This creates variations or instabilities in the anticor-rosion perforrnance.
If, however, the production of a large conversion coating weight on the outside bottom surface of the can is pursued in order to stabilize the anticorro-sion pe~ rO" "a"ce, too much conversion coaliny will be produced on the neckingor flange regions that are processed after painting. This causes the problem of paint delamination after painting.
This variation in coali"g weight among the crorel "enlio"ed regions is everi more sl~hst~rltial in the case of aged surface treatment baths where the ac-cumulated concentration of eluted aluminum in the solution has reached highvalues.
When the dro, e,nen~iol ,ed prior art surface treatment bath is used industri-ally, avoiding ~" lacce,uLable paint delamination results in the major drawback of ~ requiring the use of an effective fluoride concenbdlion, which essentially must be 30 maintained at a co"sLa~ ll value during use of the bath, that is somewhat smaller than that which would be most desirable for avoiding blackening and avoiding theror"~aLion of precipitates.
CA 022084~9 l997-06-20 - Due to this, when aluminum ions actually do elute and enter the bath, pre-cipitation occurs even for the above-described surface l,eal",e"l bath with its distinguishing feature of not containing a highly precipitation-prone solid-pro-ducing component. Even with this bath, then, problems such as equip",e"l soiling, nozle clogging, and the like, do in fact occur.
Disclosure of the Invention Problems to Be Solved by the Invention The present invention seeks to solve the problems described above for the prior art. In specific terms, the pr~senl invention introduces a bath and a pro-10 cess using said bath that not only are able to produce a highly corrosion-re-sistant, strongly paint-adherent conversion coating on the surfaces of alumin-iferous metal substrates, but which also exhibit excellent properties in terms of conversion coating uniformity, sludging inhibition, and process stability.
Summary of the Invention It has been discovered that:
(i) a treatment bath that maintains a ll a"spar~, ll appea(dl Ice can be obtained when an oxidizing agent and a hydrogen fluoride-generating compound that produces a particular value for the HF concenl, alion are also present in a surface treatment bath that contains a phosphoric acid compound and zirconium compound and has a pH of 1.5 to 4.0;
(ii) an excellent corrosion resistance and good paint adherence can be imparted to the surface of aluminiferous metal substrates by the formation thereon of a conversion coating by contacting the surface of the aluminiferous metal with the aforesaid conversion bath for 0.5 to 60 seconds; and (iii) the conversion coali"g thereby formed is very uniform, while at the same time an excellent sludging inhibition is obtained.
The highly sludging-i,lhibiled coll~rosiliol1 according to the present inven-tion for treating the surface of aluminiferous metals is a waterborne surface lreal",e"l bath that forms a conversion coating on the surface of aluminiferous metals and is chara~leri~ed in that it has a pH of 1.5 to 4.0 and comprises, pref-erably consists essentially of, or more pre~erably consists of water and the fol-lowing components:
CA 022084~9 1997-06-20 W O96/l9S95 PCTnUS95/16231 (A) at least one phosphoric acid compound (B) at least one zirconium compound, (C) at least one oxidizing agent and (D) at least one co" ,pound that is a source of hydrogen fluoride in a quantity that produces a total concer,l,dlion of hydrogen fluoride in the aqueous solution in the range from 0.0001 to 0.2 grams per liter (hereinafter us-ually abbreviated as "g/L ).
Detailed Desc,i,~.lion of the Invention and P~erer,ed Embodiments Thereof The aforesaid hydluye" fluoride-generating compound in the surface ~o treatment com~.osilio~ I accûrding to the present invention is preferably selected from hydrofluoric acid and ammonium fluoride.
The aforesaid o,(idi~i"g agent in the surface treatment composition accor-ding to the present invention preferably consists of at least one selection fromhydrogen peroxide nitrous acid organoperoxides and salts of the preceding.
The aroresaid zirconium compound(s) are ~rererably present in a surface treatment co, nposilion according to the present invention at a total conce"l, alion of 0.005 to 0.5 g/L as zirconium.
The droresaid p hospl ,oric acid compound(s) is prererably present in a sur-face l, e~L" ,enl co m posilion acco, di"g to the present invention at a concentration of 0.005 to 0.4 g/L as PO4-3 ions. The total stoichiometric equivalent as POj3 ions of all orthophosphoric acid (i.e. H3PO4) metaphosphoric acids (i.e.
[HPO3~X where x is a positive integer with a value of at least 3) and condensed phos~cl ,oric acids (i.e. H(n+2)PnOt3"~,p where n is a positive integer with a value of at least 2) and any anionic products formed by dissoci~ion of any of these acidsincluding such anions added to the composition in the form of salts is to be understood as constituting the Poi3 ions corllellt for the definition of this concer,l,dlion i"es,uec~ e of the actual extent of ionization dissociation and/or .ssoci~tion that may occur in the surface treatment composition.
The aforesaid oxidizing agent is preferably present in the surface treatment composition according to the present invention at a concentration of 0.01 to 5.0 g/L.
A highly sludging-inhibited p,ocess accor~li"g to the present invention for CA 022084~9 1997-06-20 W O96119S9S PCTnUS9S/16231 treating the surface of al~ ,irerous metal suL~sl~ales is characteri~ed by the ror",dlion of a conversion coating on the surface of aluminiferous metal by con-tacting said surface for 0.5 to 60 seconds with a treatment bath containing any surface l,eal",enl composition as described directly above and there~rler, optionally, subjecting said surface to a water rinse and drying.
When prior art surface ll eat" ,enl agents with their relatively slow reaction rates are sprayed on an article shaped like aluminum Dl cans, the resulting conversion coating usually will not be uniform, because of dirrere"ces in bath flow rate and surface/bath contact conditions that occur between different ~o regions. The conversion coatiny may therefore exhibit an uneven performance.
In the specific case of aged surface treatment solutions in which the aluminum ions cGncenlrdlion in the solution has reached high levels, fluorine is consumedfrom the fluorocor"plex of zirconium and it becomes necess~ry to add additional fluorine source in order to keep the zirconium stably dissolved in the bath, i.e., to keep the treatment bath transparent. This c~uses an even more pronounced variation in coating weight among the various regions of the can.
The inventors discovered that the rate of the conversion coating formation reactions and the ~" lirul " ,ily of the conversion coating can be improved through the presence of HF--in addition to zirconium, phosphoric acid, and oxidizing agent--for the purpose of slabili~i"g the quality by eliminating the variations in coating weight between the regions of such a shaped article that would otherwisearise from differences in reaction rate.
It was also discovered that managing the HF concentration to 0.0001 to 0.2 g/L in order to inhibit pr~c;,.~ilatiol) of the zirconium in the treatment bath leads to an improved inhibition of sludge ro~",alio,) even in the case of aged treatment baths having high aluminum ion concentrations.
Coating formation is believed to occur during treatment with a zirconium-~nlail lil ,g treatment bath bec~l Ise of an i"~ ease in pH at the interface between the metal substrate and the treatment bath. On the other hand, with regard to 30 the hydrofluoric acid and aluminum fluorocomplexes present in conversion l,edl",enl baths, it is known that the structures of these compounds change as a function of the pH of the treatment bath. Free fluoride (F-), hydrofluoric acid CA 022084~9 l997-06-20 W O96/19S95 PCTrUS95/16231 (HF), and various aluminum fluorocomplexes may be present in an acidic ~ql leo~ 's solution containing aluminum and fluorine. Their proportions vary with variations in the pH of the ~q~eo~ls solution. Conversion coating formation reactions are believed to occur due to the decline in the HF conce"l, dlion in the vicinity of the inle,race. Thererore, control of the HF concentration in the l,edl"~enl bath becomes necess~y in orderto l"ailllain a high conversion activity and a transparent appearance on the part of the treatment bath.
The HF concer,lr~lion is measured in the present invention as follows. A
corn~"el~,ially available fluoride ion reference solution is first diluted with a com-mercially available solution for adjusting the pH/ionic strength, in order to prepare three rerere"ce solutions with the following F- concentrations: F- = 1 mg/L, F- =
10 mg/L, and F- = 100 mg/L. These are then equilibrated at the specified temperature and used to calibrate the measurement values of a fluoride ion meter. A sample of the surface treatment solution is then equilibrated at the specified temperature, and its F- concer,l, ;alion is obtained using the calibrated fluorine ion meter and converted to the molar concenl, clion, designated as "[F-]".
The pH of the treatment bath is also measured and the molar H+ concentration, designated as "[H']", is derived from this. The molar conceniralion of HF, desiyndled as "[HF]", is then calculated from the known dissociation constant for HF according to the following equation: [HF] = {~H+] ~ [Fl/10-3'7}. The lHF] value thus obtained is converted to g/L by multiplying by the gram molecular weight ofHF.
The following concel,l,alions are preferred for the surface treatment composition accordil-g to the present invention: for the zirconium compound, 0.005 to 0.5 g/L as zirconium; for the phosphoric acid compound, 0.005 to 0.4 g/L as PO4 ions; for the oxidizing agent, 0.01 to 5 g/L.
With regard to the concenll alions of the phosphoric acid compound, zir-conium cor"pound, and oxidi~ing agent in the surface treatment composition ac-cordir,g to the present invention, if any of these falls below the above-specified lower limits, the resulting treatment bath will have an inadequate conversion coali"g formation activity and may not be able to lay down a conversion coating of sufficient thickness. No additional increases in effect are obtained when these CA 022084~9 1997-06-20 W O 96119S9S P~1-IU~I16231 conce, Itrations e~ eed the above-speciried upper limits, and such conce"lralions therefore serve merely to raise the cost.
Zirconium-containing sludge is readily produced when the concentration of the hy.l~oge~, fluoride-source compound in the surface treatment composition ' 5 according to the present invention falls below 0.0001 g/L as HF (hydrogen fluoride). An excessive etch, which impedes the for",alion of a conversion coating, occurs when this value exceeds 0.2 g/L.
A surface treatment process acco,.liny to the ~,rese,)l invention comprises the formation of a conversion coating by bringing the target surface of the aluminiferous metal sul.stlale into conlac~ with a treatment bath containing treat-ment co",posilion as described above and then, optionally but preferably, exe-cuting thereon a water rinse and drying. Said contact between the treatment bath and metal surface may be implemented, using spray or immersion tech-nology, as a continuous one-step process or as an intermittent multi-step pro-~5 cess. The total conla~;t time preferably should be from 0.~ to 60 seconds.
BeG~ se the specific component composition of the treatment bath is able to in-hibit sludge adhesion to the equipment, the described process according to the present invention can achieve an excellent operating stability and a high treat-ment efficiency.
The surface treatment bath according to the present invention is an acidic treatment bath that contains phosphate ions, a zirconium compound, fluoride, and oxidi~i"g agent as its essential components. The source of the phosphate ions in this ~, edl,l)el)l bath prererably is phosphoric acid, ammonium phosphate, and/or an alkali metal salt of phosphoric acid, with phosphoric acid and 25 ammonium phosphate more preferred, taking into consideration sludging inhibition. The content is preferably 0.005 to 0.4 g/L as phosphate (PO4) ions, while the range of 0.01 to 0.20 g/L as phosphate ion is even more preferred.
P hos,cl ,dle ion concerlt, dlions below 0.005 g/L result in a poor reactivity, which makes it very difficult to form satisraclo"/ coalings. At the other extreme, no -30 additional benefits are obtained at cor,ce,)lralions in excess of 0.4 g/L, which thererore serve merely to raise the cost of the treatment bath and thus are eco-nomically undesirable.
CA 022084~9 1997-06-20 W O96/195g5 PCTnUS9S/16231 The presence of a zirconium compound in treatment baths according to the pr~senl invention is most advantageously brought about through the use of water-soluble col npounds of zirconium more preferably water-soluble fluorozir-conium complexes and still more ,l~referably fluo~i,co"ic acid (H2ZrF6) and its salts. With regard to the use of the oxide hydroxide nitrate or phosphate of zir-conium this should be acco",,l~anied by the simultaneous addiliol, of fluoride that fu, nishes hydrogen fluoride in sufficient quantity to transform the zirconium into a water-soluble fluorocomplex and thereby prevent production of a precipitate.
The ,i, ~".um c~mpound conlenl is ,c rerer~bly 0.005 to 0.5 g/L as zirconium andis more l~r~rerably 0.01 to 0.1 g/L as zirconium. Adequate film formation may not occur at a zirconium conlent below 0.005 g/L. No additional benefits are obtained at conce"l, dlions in excess of 0.5 g/L which therefore serve merely toraise the cost of the treatment bath and thus are economically undesirable.
The presence of h~dl ~gen fluoride in the treatment bath according to the ,~resel ,l invention is most adva"lageously brought about by adding hydrofluoricacid or al~ ,monium fluoride. The prt:rel l~cl HF conlenl falls in the range of 0.0001 to 0.2 g/L and more preferably falls in the range of 0.01 to 0.1 g/L.
The oxidizing agent present in the treatment bath acco, .3i"g to the present invention is exemplified by hydrogen peroxide nitrous acid and its salts and or-20 ganoperoxides. The use of hydrogen peroxide is most preferred based on aconsideration of the ease of treating the waste water produced by the process accor.ling to the present invention. The oxidizing agent functions to acceleratethe rate of the reacLions that produce the zirconium coating. The oxidizing agent content is preferably 0.01 to 5 g/L and more prerelably 0.1 to 1.0 g/L. The reaction-accelerating activity may be unsatisfactory at oxidizing agent concer,l, dlio,-s below 0.01 g/L. No problems are associated with concentrationsin excess of 5 g/L but such concer,l,aLions do not provide any additional benefit and thus merely drive up the costs and are therefore economically undesirable.
The pH of the l, eal, nenl bath should be adjusted to 1.5 to 4Ø The extent 30 of etching becomes excessive at pH values below 1.5 and impedes conversion coating formation. The etch becomes too weak at pH values in excess of 4.0 and makes it dfflicult to form a highly corrosion-resistant coating. The preferred CA 022084~9 l997-06-20 WO 96/lg59S PCI/US95/16231 pH range is 2.3 to 3Ø The pH can be adjusted through the use of an acid such as phosphoric acid, nitric acid, or hydrochloric acid, or through the use of an alkali such as ammonium h~dloxide, a""~onium cd,l,onale, or sodium hydroxide.
rhospl ,o, ic acid and nitric acid are the prere" ed acids for adjusting the pH, while ,~ 5 basic ammo,-ium compounds are prefer,ed as the alkali.
The stability of the l,e~",enl bath can be substantially impaired by metal ions, such as those of copper, mdnydnese, and the like, that are produced when an alloying co",pol.ent is eluted from the surface of the aluminiferous metal substrate. This can result in such problems as sludge production, precipitate formation, and the adhesion of sludge and/or precipitate to the equipment and the like. In order to prevent this from happening, an organic acid or salt thereof, for exdr"ple, gluconic acid, oxalic acid, and their salts, may be added in order to chelate such components and stabilize the bath.
A water-soluble fluoroco",plex of, for example, titanium, silicon, and the like, may also be added to the surface treatment bath according to the present invention along with the zirconium compound, for example, a water-soluble fluoro~i,conium complex.
An example of the surface treatment process according to the present invention for an aluminiferous metal substrate includes the following steps:
20 (1) surface cleaning: degreasing (acidic, alkaline, or solvent-based degreasers may be used) (2) water rinse (3) conversion coating treatment (surface treatment using a treatment bath according to the present invention) (4) water rinse (5) rinse with deionized water (6) drying The treatment temperature with the surface treatment bath acco~ ,9 to the presenl invention is not crucial, and, for example, a temperature range from- roorrl temperature to 90 ~C can be used. However, taking into consideration the stability, operating behavior, and productivity characteristics of the treatmentbath, the bath is preferably used at from 25 ~C to 50 ~C. The treatment time is CA 022084~9 1997-06-20 W O96/lgS9S PCTnUS95/16231 also not crucial but treatment times of for example 0.5 to 60 seconds are preferred and the range of 5 to 30 seconds is even more preferred. A full reaction is not usually ~btail ,ed in less than 5 seconds; this would prevent the ro"n~lion of a highly corrosion-resistant coating. At the other end of the rangeno additional increase in pe,ro""a"ce has been observed at times above 60 seconds.
The surface treatment bath and process according to the present inven-tion will be illustrated through the working examples provided below.
Exalll~,lcs The following sam,~!es and pe,~n,lance evaluation tests were used in the working and cor"parali,le examples.
(1 ) Samples The materials were aluminum alloy (A3004) sheets and aluminum Dl cans fabricated from this type of aluminum alloy sheet. These were each cleaned prior to surface ll eal" ,enl according to this invention with a hot aqueous solution of an acidic degreaser (PALKLINTM 500 a product of Nihon Parkerizing Company Limited Tokyo).
(2) Evaluation methods (a) Corrosion resistance and coating uniformity The corrosion resistance and coating uniformity were evaluated on the aluminum Dl cans based on the resistance to blackening by boiling water. The resistance to blackening by boiling water was tested as follows. After surface l, eal" ,enl the aluminum Dl cans were immersed in boiling tap water for 30 min-utes This was followed by a visual deler",ir,ation of the degree of discoloration (blackening) thereby prorll Iced at the elevations (regio"s where the bath flow rate was fast) and depression (region where the bath flow rate was slow) of the aluminum Dl cans. Said elevations correspond to the rib and exterior sidewall regions of actual aluminum Dl cans while the depression corresponds to the dome reglon.
The corrosion resistance was evaluated by scoring the test results on the following scale:
+ = noblackening CA 022084~9 l997-06-20 W O96/1gS95 PCTnUS95/1623 = blackening over part of the suRace x = blackening over the entire surface.
The codlil~g ~" ~irur,,,ily was rated as follows based on the resulting loca-tion-specific ev~ tion of the r~sislance to blackening by boiling water: a scores of "~" ,irc,r"~" was render~d when both locations were free of blackening, while a score of "nonuniform" was rendered when blackening occurred at only one location.
(b) Paint adl ,erence After the aluminum alloy (A30f~4) sheet had been subjected to the suRace ~o treatment, it was coated with a can-grade epoxy-urea paint to give a paint film thickness of 5 to 7 micfo",eters. This was followed by baking and drying to givea painted panel. A test panel was then prepared by bending the painted panel in a bending tester, and this test panel was subjected to a peel test using cellophane tape. The test results were scored as follows:
+ = peeling did not occur x = peeling occurred.
Bath transparency The treal"~enl bath which had been used in the particular example or con,pardli~/e example was held at 40 ~C for 1~ days. The amount of zirconium in the bath was measured both before and after this holding period, and the presence/absence of precipitate was determined from the difference in these values. A "+" indicates that prec;~,ilale was not producerl while "x" indicates that precipitate was produced.
~ Confirming test for sludge adhesion The treatment bath which had been used in the particular example or co" ~par~ /e example was supplied continuously for 16 hours to spray treatment using a small-scale sprayer held at 40 ~C. During this time, the development of sludge at the nozle of the device was inspected visually. A "+" indicates no - sludge adhesion, while "x" indicates that sludge adhesion occurred.
Example 1 The c;ea,led aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 20 seconds with suRace treatment bath (1) (composition given W O96/lgS95 PCTnUS9~/16231 below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The sa" I,~les thus obtained were evaluated for their corrosion resistance, codling uniformity, and paint adherence.
The aluminum nitrate was used as an aluminum source for the purpose of artificially aging the treatment bath.
Surface treatment bath (1 ) phosphoric acid 30 ppm as P04 ions fluo,ilconic acid 30 ppm as Zr hydrogen peroxide 100 ppm as H202 aluminum nitrate 100 ppm asAI
pH - 3.0 (adjusted with aqueous ammonia) conce"lralion of HF = 11 ppm (adjusted with hydrofluoric acid).
Example 2 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 40 seconds with surface treatment bath (2) (composition given below) heated to 40 ~C~ This was followed by rinsing with tap water, spray rins-ing for 10 second~ with deioni~ed water, and then drying in a hot-air dr,ving oven.
The samples thus oblained were ev~ tP, :I for their corrosion resistance, coating uniformity, and paint adherence.
Surface treatment bath (2) phospl1oric acid 20 ppm as P04 ions fluo~irco,1ic acid 10 ppm as Zr hydrogen peroxide 300 ppm as H2O2 aluminum nitrate 50 ppm as Al pH = 2.7 (a~justed with aqueous al~ OI ,ia) conce"ll dlion of HF = 9 ppm (adjusted with hydrofluoric acid) Example 3 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 15 seconds with surface treatment bath (3) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air drying CA 022084~9 1997-06-20 W Og6119Sg5 1~1/~',5/16231 oven. The Sdl nples thus obtained were ev~ t~:I for their corrosion resistance coating uniformity and paint adherence.
Surface treatment bath (3) phosphoric acid 40 ppm as PO4 ions ,~ 5 fluo~i~onic acid 40 ppm as Zr hydrugenperoxide 200 ppm as H2O
aluminum nitrate 200 ppm as Al pH = 2.3 (adjusted with aqueous ar"r"ûr,ia) concentration of HF = 15 ppm (adjusted with hydrofluoric acid) ,0 Example 4 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were immersed for 10 seconds in surface l,edt",enl bath (4) (composition given below)heated to 30 ~C. This was followed by rinsing with tap water spray rinsing for 10 seconds with deionized water! and then drying in a hot-air drying oven. The 5 samples thus obtained were evaluated for their corrosion resistance coating uniformity and paint adherence.
Surface treatment bath (4) phosphoricacid 150 ppm as PO4 ions fluozirconic acid 100 ppm as Zr hydrogen peroxide 400 ppm as H2O2 aluminum nitrate 300 ppm as Al pH = 2.5 (adjusted with aqueous ammonia) concentration of HF = 70 ppm (adjusted with hydrofluoric acid) Example 5 The claaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 5 secon ds with surface l,eal",e, ll bath (5) (composition given below) heated to 30 ~C. This was followed by rinsing with tap water spray rinsing for 10 seconds with deionized water and then drying in a hot-air drying oven. The samples thus obtained were evaluated for their corrosion resistance coating uniformity and paint adherence.
CA 022084~9 1997-06-20 W O96/19S9S PCTrUS95/16231 Surface treatment bath (5) phosphoric acid 400 ppm as P04 ions ammonium fluo,ircGnate 200 ppm as Zr hydrogen peroxide 500 ppm as H2O2 aluminum nitrate 500 ppm as Al pH = 2.5 (adjusted with aqueous ammonia) conce"l,alion of HF = 100 ppm (adjusted with hydrofluoric acid).
Example 6 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were o sprayed for 15 seconds with surface treatment bath (6) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seco, Icls with deionized water, and then drying in a hot-air drying oven.
The samples thus obtained were ev~ ted for their corrosion resi~lance, coating uniformity, and paint adherence.
Surface treatment bath (6) phosphoricacid 50 ppm as PO4ions zirconium oxide 30 ppm as Zr hydrogen peroxide 200ppm as H2O2 aluminum nitrate 200 ppm as Al pH = 2.3 (adjusted with aqueous ammonia) concentration of HF = 13 ppm (adjusted with hydrofluoric acid) Example 7 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 15 seconds with surface treatment bath (7) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seconds with deionized water, ar~d then drying in a hot-air drying oven.
The samples thus obtained were ev~ ted for their corrosion resislance, coating uniformity, and paint adherence.
Surface treatment bath (7) phosphoric acid 50 ppm as P O4 ions r zirconium oxide 30 ppm as Zr hydrogen peroxide 200 ppm as H2O2 CA 022084~9 l997-06-20 W Og6/l9S9S PCTnUS95/16231 aluminum nitrate 100 ppm as Al pH = 3.5 (adjusted with ~s~ueous am~,onia) concerlL, dlion of HF = 7 ppm (adjusted with hydrofluoric acid).
Compalalive Example 1 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 10 seconds with surface treatment bath (8) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The sa~ )'es thus obtained were evaluated for their corrosion resistance, .0 coaling uniformity, and paint adherence.
Surface l~eal~,enl bath (8) (no oxidizing agent) phosphoricacid 30ppm as PO4 ions fluo~ircGnic acid 30 ppm as Zr aluminum nitrate 200 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) conce"l, dlion of HF = 15 ppm (~ sted with hydrofluoric acid).
Comparative Example 2 The claal1ed aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 10 seconds with surface l,eal",ent bath (9) (composition given below) heated to 50 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seconds with deionized water, and then drying in a hot-air drying oven.
The samples thus obtained were evaluated for their corrosion resisla"ce, coatinguniformity, and paint adherence.
Surface treatment bath (9) (no zirconium compound) phosphoricacid 50 ppm as PO4ions hydrofluoricacid 220ppm as F
hydrogen peroxide 500 ppm as H2O2 aluminum nitrate 100 ppm asAI
pH = 2.5 (adjusted with aqueous al"",o"ia) concentration of HF = 10 ppm (adjusted with hydrofluoric acid) Comparative Example 3 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were CA 022084~9 1997-06-20 W O96/l9S95 PCTnUS95116231 sprayed for 20 seconds with surface treatment bath (10) (composition given below) heated to 35 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The samples thus obtained were evaluated for their corrosion resistance, 5 coating uniformity, and paint adherence.
Surface l,eal",e"t bath (10) fluo~irco~,ic acid 40 ppm as Zr hydrogen peroxide 500 ppm as H2O2 aluminum nitrate 200 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) concentration of HF = 50 ppm (adjusted with hydrofluoric acid).
Comparative Example 4 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 15 seconds with surface treatment bath (11) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The sarnples thus oblai"ed were evaluated for their corrosion resistance, coating uniformity, and paint adherence.
Surface treatment bath (11 ) 20 phosphoric acid 50 ppm as P04 ions fluozirconic acid 50 ppm as Zr hydrogen peroxide 300 ppm as H202 aluminum nitrate 200 ppm as Al pH = 2.7 (adjusted with aqueous ammonia) concnetration of HF = 0.05 ppm (adjusted with hydrofluoric acid).
Comparative Example 5 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 10 seconds with surface treatment bath (12) (composition given . below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-30 ing for 10 seconds with ~Jeior,i~ed water, and then drying in a hot-air drying oven.
The san ~ les thus oL)lained were evaluated for their co~ I osio, I resi~la~ ~ce, coating uniformity, and paint adherence.
CA 022084~9 1997-06-20 WO g6/lg5gS PCI/US95/16231 Surface treatment bath (12) ,uhospl ,oric acid 40 ppm as PO4 ions zirconium oxide 40 ppm as Zr hydrogen peroxide 300ppm as H2O2 ,~ 5 aluminum nitrate 200 ppm as Al pH = 2.8 (adjusted with aqueous ammonia) conce"Lrdlion of HF = 0.01 ppm (adjusted with hydrofluoric acid).
GGr"parali~/e Example 6 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were 10 sprayed for 15 seconds with surface treatment bath (13) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rinsing for 10 seconds with deionized water, and then drying in a hot-air dryingoven. The samples thus obtained were evaluated for their corrosion resistance, coating uniformity, and paint adherence.
Surface lledlll~enl bath (13) phosphoricacid 40ppm as PO4 ions fluo~irconic acid 40 ppm as Zr aluminum nitrate 300 ppm as Al pH = 3.0 (adjusted with aqueous ammonia) conce"l, alion of HF = 15 ppm (adjusted with hydrofluoric acid).
Comparative Example 7 The cleaned aluminum Dl cans and cleaned aluminum alloy sheets were sprayed for 30 seconds with surface treatment bath (14) (composition given below) heated to 40 ~C. This was followed by rinsing with tap water, spray rins-ing for 10 seconds with CieiOI ,i~ed water, and then drying in a hot-air drying oven.
The samples thus oblai. ,ed were evaluated for their corrosion r esisla,)ce, coating uniformity, and paint adherence.
SurFace treatment bath (14) phosphoric acid 100 ppm as PO4 ions fluo~ircol ,ic acid 100 ppm as Zr aluminum nitrate 300 ppm as Al pH = 3.0 (adjusted with aqueous am~onia) W O 96/19S9S PCTrUS9~/16231 co"cenl~dlio" of HF = 20 ppm (adjusted with hydrofluoric acid).
Test results from all the Examples and Co",pa,dli~/e examples are report-ed in Table 1.
Exa"~ples 1 to 7 used surface L,eat"~e,ll baths and surface treatment pro-cesses accordi"g to the present invention and Table 1 col,ri~",s the followingresults for these examples: the obtained conversion coatings exhibited an excellent corrosion resistance and paint adherence; the obtained conversion codlings were very uniform; the surface treatment baths maintained their trans-parency; and sludge adhesion was thoroughly inhibited. In contrast Com-10 parative Examples 1 to 7--which used surface treatment baths outside thescope of the invention--in each case gave an unsatisfactory overall perform-ance because each was found to be deficient in at least one aspect (corrosion resistance paint adherence conversion coating uniformity treatment bath transparency and inhibition of sludge adhesion).
The surFace lreal" ~enl con,position and surface treatment process accord-ing to the presenl invention impart an excellent corrosion resistance and ex-cellent paint a.lher~nce to the surface of aluminiferous metal substrates prior to the painting thereof. Other desirable effects demonstrated by this composition and process are a very uniform conversion coating excellent treatment bath transparency and an excellent inhibition of sludge adhesion.
These ~arac~ri~lics confer a high degree of practical utility on the bath and prucess accor~i"g to the present invention for treating the surface of alumin-iferous metal suL,~lrales.
W Og6/19SgS PCTnUS95/16231 E~ample Corrosion Resistanceand Uniformity Paint Bath Inhibition or Com- Adher- Trans- of Sludge parison Elevations Depressions Uniformity ence parency Adhesion Example Ex 1 + + .. ,,;ru..... + + +
Ex 2 + + uniform + + +
Ex3 + + uniform + + +
Ex 4 + + ~II.ir~ + + +
Ex 5 + +~ ;ru~ .... + + +
Ex 6 + + ulfirulln + + +
Ex 7 + + ullirullll + + +
CE 1 x x - + + +
CE2 x x - + + +
CE3 x x - + + +
CE 4 + + uniforrn + x x CE 5 x (~nomlniform + x x CE6 x . + nonuniforrn + + +
CE 7 (~ + nonuniforrn x + +
Abbreviations for Table 1 "Ex" = "Example"; "CE" = "Colllp~ re Fx~ ple".
Claims (19)
1. A highly sludging-inhibited aqueous liquid composition for treating the surface of aluminiferous metals, said composition having a pH of 1.5 to 4.0 and comprising water and:
(A) at least one phosphoric acid compound, (B) at least one zirconium compound, (C) at least one oxidizing agent, and (D) at least one compound that is a source of hydrogen fluoride, in a quantity that produces a total concentration of hydrogen fluoride in the aqueous composition in the range from 0.0001 to 0.2 g/L.
(A) at least one phosphoric acid compound, (B) at least one zirconium compound, (C) at least one oxidizing agent, and (D) at least one compound that is a source of hydrogen fluoride, in a quantity that produces a total concentration of hydrogen fluoride in the aqueous composition in the range from 0.0001 to 0.2 g/L.
2. An aqueous liquid composition according to claim 1, in which component (D) is selected from the group consisting of hydrofluoric acid, ammonium fluoride, and mixtures thereof.
3. An aqueous liquid composition according to claim 2, in which component (C) is selected from the group consisting of hydrogen peroxide, nitrous acid andits salts, organoperoxides, and mixtures of any two or more of the preceding.
4. An aqueous liquid composition according to claim 1, in which component (C) is selected from the group consisting of hydrogen peroxide, nitrous acid andits salts, organoperoxides, and mixtures of any two or more of the preceding.
5. An aqueous liquid composition according to claim 4, in which the concentration of component (B) is from 0.005 to 0.5 g/L, measured as zirconium.
6. An aqueous liquid composition according to claim 3, in which the concentration of component (B) is from 0.005 to 0.5 g/L, measured as zirconium.
7. An aqueous liquid composition according to claim 2, in which the concentration of component (B) is from 0.005 to 0.5 g/L, measured as zirconium.
8. An aqueous liquid composition according to claim 1, in which the concentration of component (B) is from 0.005 to 0.5 g/L, measured as zirconium.
9. An aqueous liquid composition according to claim 8, in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
10. An aqueous liquid composition according to claim 7 in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
11. An aqueous liquid composition according to claim 6 in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
12. An aqueous liquid composition according to claim 5 in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
13. An aqueous liquid composition according to claim 4 in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
14. An aqueous liquid composition according to claim 3 in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
15. An aqueous liquid composition according to claim 2 in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
16. An aqueous liquid composition according to claim 1 in which the concentration of component (A) is from 0.005 to 0.4 g/L as PO4 ions.
17. An aqueous liquid composition according to any one of claims 1 through 16, in which the concentration of component (C) is 0.01 to 5.0 g/L.
18. A process of forming a protective conversion coating on an aluminiferous substrate surface, said process comprising contacting the substrate surface withan aqueous liquid composition according to claim 17 for from 0.5 to 60 seconds, and, optionally, thereafter subjecting said substrate surface to a water rinse and drying.
19. A process of forming a protective conversion coating on an aluminiferous substrate surface, said process comprising contacting the substrate surface withan aqueous liquid composition according to any one of claims 1 through 16 for from 0.5 to 60 seconds, and, optionally, thereafter subjecting said substrate surface to a water rinse and drying.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JPH6/320,545 | 1994-12-22 | ||
| JP32054594A JP3349851B2 (en) | 1994-12-22 | 1994-12-22 | Surface treatment composition for aluminum-containing metal material excellent in sludge suppression property and surface treatment method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2208459A1 true CA2208459A1 (en) | 1996-06-27 |
Family
ID=18122634
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2208459 Abandoned CA2208459A1 (en) | 1994-12-22 | 1995-12-22 | Low sludging composition and process for treating aluminum and its alloys |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0799326A4 (en) |
| JP (1) | JP3349851B2 (en) |
| AR (1) | AR000514A1 (en) |
| AU (1) | AU4469796A (en) |
| BR (1) | BR9510243A (en) |
| CA (1) | CA2208459A1 (en) |
| TR (1) | TR199501662A2 (en) |
| WO (1) | WO1996019595A1 (en) |
| ZA (1) | ZA9510615B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CA2300942C (en) | 1997-08-21 | 2008-05-13 | Henkel Corporation | Process for coating and/or touching up coatings on metal surfaces |
| IL134925A0 (en) * | 1997-09-17 | 2001-05-20 | Brent Int Plc | Method and compositions for preventing corrosion of metal substrates |
| US6432603B1 (en) * | 1998-11-27 | 2002-08-13 | Canon Kabushiki Kaisha | Process for producing electrophotographic photosensitive member |
| US6168868B1 (en) * | 1999-05-11 | 2001-01-02 | Ppg Industries Ohio, Inc. | Process for applying a lead-free coating to untreated metal substrates via electrodeposition |
| DE19933189A1 (en) * | 1999-07-15 | 2001-01-18 | Henkel Kgaa | Process for the protection against corrosion or aftertreatment of metal surfaces |
| JP2001342578A (en) * | 2000-05-31 | 2001-12-14 | Honda Motor Co Ltd | Surface treatment agent for metal |
| JP4707258B2 (en) * | 2001-05-07 | 2011-06-22 | 日本ペイント株式会社 | Acid cleaning agent for chemical film and treatment method |
| JP5111701B2 (en) * | 2001-09-11 | 2013-01-09 | 日本ペイント株式会社 | Surface treatment method for aluminum or aluminum alloy |
| US6761933B2 (en) | 2002-10-24 | 2004-07-13 | Ppg Industries Ohio, Inc. | Process for coating untreated metal substrates |
| TW200417419A (en) * | 2002-12-24 | 2004-09-16 | Nippon Paint Co Ltd | Chemical conversion coating agent and surface-treated metal |
| JP4510079B2 (en) | 2005-03-16 | 2010-07-21 | 日本パーカライジング株式会社 | Surface-treated metal material |
| US7815751B2 (en) | 2005-09-28 | 2010-10-19 | Coral Chemical Company | Zirconium-vanadium conversion coating compositions for ferrous metals and a method for providing conversion coatings |
| US7980000B2 (en) * | 2006-12-29 | 2011-07-19 | Applied Materials, Inc. | Vapor dryer having hydrophilic end effector |
| US8673091B2 (en) | 2007-08-03 | 2014-03-18 | Ppg Industries Ohio, Inc | Pretreatment compositions and methods for coating a metal substrate |
| US9574093B2 (en) | 2007-09-28 | 2017-02-21 | Ppg Industries Ohio, Inc. | Methods for coating a metal substrate and related coated metal substrates |
| JP5215043B2 (en) * | 2008-06-02 | 2013-06-19 | 日本パーカライジング株式会社 | Metal surface treatment liquid and surface treatment method |
| US8282801B2 (en) | 2008-12-18 | 2012-10-09 | Ppg Industries Ohio, Inc. | Methods for passivating a metal substrate and related coated metal substrates |
| US9273399B2 (en) | 2013-03-15 | 2016-03-01 | Ppg Industries Ohio, Inc. | Pretreatment compositions and methods for coating a battery electrode |
| PL3031951T3 (en) * | 2014-12-12 | 2018-03-30 | Henkel Ag & Co. Kgaa | Optimized process control in the pretreatment of metals to protect against corrosion on the basis of baths containing fluoride |
| FR3044329A1 (en) * | 2015-11-27 | 2017-06-02 | Constellium Neuf-Brisach | METHOD FOR ELECTROLYTIC DEPOSITION OF AN ALTERNATING CURRENT CONVERSION LAYER |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3539403A (en) * | 1966-12-07 | 1970-11-10 | Collardin Gmbh Gerhard | Solutions for the deposition of protective layers on zinc surfaces and process therefor |
| JPS5424232A (en) * | 1977-07-26 | 1979-02-23 | Nippon Packaging Kk | Surface treating method of aluminum |
| CA1333043C (en) * | 1988-02-15 | 1994-11-15 | Nippon Paint Co., Ltd. | Surface treatment chemical and bath for aluminium and its alloy |
| JPH0364484A (en) * | 1989-08-01 | 1991-03-19 | Nippon Paint Co Ltd | Surface treating agent and treating bath for aluminum or aluminum alloy |
| US5139586A (en) * | 1991-02-11 | 1992-08-18 | Coral International, Inc. | Coating composition and method for the treatment of formed metal surfaces |
| GB2259920A (en) * | 1991-09-10 | 1993-03-31 | Gibson Chem Ltd | Surface conversion coating solution based on molybdenum and phosphate compounds |
| US5143562A (en) * | 1991-11-01 | 1992-09-01 | Henkel Corporation | Broadly applicable phosphate conversion coating composition and process |
| JPH0748677A (en) * | 1993-07-05 | 1995-02-21 | Nippon Parkerizing Co Ltd | Aluminum di can and common surface treatment solution and process for tin di can |
| JP2828409B2 (en) * | 1994-03-24 | 1998-11-25 | 日本パーカライジング株式会社 | Surface treatment composition for aluminum-containing metal material and surface treatment method |
-
1994
- 1994-12-22 JP JP32054594A patent/JP3349851B2/en not_active Ceased
-
1995
- 1995-12-13 ZA ZA9510615A patent/ZA9510615B/en unknown
- 1995-12-15 AR AR33464295A patent/AR000514A1/en unknown
- 1995-12-22 BR BR9510243A patent/BR9510243A/en not_active Application Discontinuation
- 1995-12-22 CA CA 2208459 patent/CA2208459A1/en not_active Abandoned
- 1995-12-22 AU AU44697/96A patent/AU4469796A/en not_active Abandoned
- 1995-12-22 WO PCT/US1995/016231 patent/WO1996019595A1/en not_active Application Discontinuation
- 1995-12-22 EP EP95943426A patent/EP0799326A4/en not_active Withdrawn
- 1995-12-22 TR TR95/01662A patent/TR199501662A2/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| AU4469796A (en) | 1996-07-10 |
| TR199501662A2 (en) | 1996-07-21 |
| EP0799326A1 (en) | 1997-10-08 |
| BR9510243A (en) | 1997-11-04 |
| EP0799326A4 (en) | 1997-12-10 |
| WO1996019595A1 (en) | 1996-06-27 |
| AR000514A1 (en) | 1997-07-10 |
| JP3349851B2 (en) | 2002-11-25 |
| JPH08176841A (en) | 1996-07-09 |
| MX9704518A (en) | 1997-10-31 |
| ZA9510615B (en) | 1996-07-03 |
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