Note: Descriptions are shown in the official language in which they were submitted.
WO 95/25831 PCT/US95/03192
- 2 1 8 6~25
Desc, i,l~liGI)
COMPOSITION AND PROCESS FOR TREATING THE SURFACE OF
ALUMINIFEROUS METALS
Technical Field
This invention relates to a novel cor"posilion and ~ Od for lrealing the
surfaces of aluminiferous metals d~i"ed as aluminum and aluminum alloys
which contain at least 45 % by weight of aluminum in order Ll ,ereby to provide
such metal surfaces prior to their painting with an excellent cor, osio" resistance
and paint adl ,ere"ce. This invention may be applied with particularly good ef-
fects to the surface t~eat,nenl of aluminum drawn-and-ironed (hereinafter usually
abbreviated 'Dl ) can stock. More specifically in the case of aluminum Dl cans
fab, icaled by the drawing-and-ironing of aluminum alloy sheet the surface treat-
0 ment composition and method according to the present invention are able to
provide the surface of the can prior to the paL lliny or p, i, Iting ll ,ereor with an ex-
cellent co"osion resialdnce and paint adl ,erence in a much shorter period of time
than in prior art Illelhods.
Background Art
Baths for l,eaLing the surface of aluminiferous metals may be broadly clas-
sified into chror"dle-type treatment baths and non-~;i,ro",ale-type treatment
baths. The d "~",ate-type t,~dt",enl baths typically occur as cl ,ro",ic acid chro-
mate conversion l,edt",ent baths and phpâphOIic acid cl ,r~,",ale conversion treat-
ment baths. Chromic acid chror"ate conversion lreal",el,l baths were first util-ized in about 1950 and are in wide use even at pr~sent for example, for heat ex-changer fins and the like. Chromic acid cl ,ror"ale conversion treatment baths
cG"lai" chromic acid (CrO3) and hydrofluoric acid (HF) as their base col"pon-
ents and may contain a conversion accelerator as desired. These baths form
a conversion coating on the metal surface that contains small amounts of hexa-
valent ci,rol"ium.
The phosphoric acid cl,ro",ale conversion ~,eal",enl bath was invented
in 1945 (United States Patent Number 2,438 877). This conversion bath con-
tains chromic acid (CrO3) phosphoric acid (H3PO4) and hydrofluoric acid (HF)
as its base components. The main component in the coali"y produced by this
WO 95/25831 PCT/US95/03192
2186025
bath is hydrated chromium phospl)ale (CrPO4 4H20). Since this conversion
coating does not c~"lain hexavalent chromium this bath is also in wide use at
prese, It as for example a paint undercoat l, edtl "en~ for the lid and body of bev-
erage cans.
The above-described ~ro",dte-type surface l,t:dt"Jent baths cGntain toxic
hexavalent chromium but envir~r",!enlal cGnside,atio"s make it desirable to use
hexavalent chromium-free l,eat",enl baths. The tl~dtlllel ,l bath taught in Japan-
ese Patent Application Laid Open [Kokai or Unexamined] Number Sho 52-
131937 [131 937/1977] is typical of invenliGns relating to non-chromate-type
o (chromium-free) surface treatment baths. This treatment bath is an acidic (pH
= appr~Ai" ,alely 1.0 to 4.0) U/dtel bo, I ,e COdlil Iy solution that c~"tail ,s phosphate
fluoride and zirconium or titanium or both. Treatme"l of metal surfaces with this
non~;l"o",ale-type surface treatment bath produces thereon a conversion film
whose main component is zirconium or titanium oxide.
Non cl ,ro",dte-type l,eat",enl baths are currently widely used for alumin-
um Dl cans bec~use they offer the advanlage of being free of hexavalent chromi-
um although treatment times of at least 15 secGnds are required with these
baths in orderto obtain an industrially s~lisr~ctoly pe,fo""d"ce (c~r,osion resist-
ance). On the other hand shG, lel)ing the surface t, eatmel)l time in the surface
treatment of aluminiferous metals has become an i",p~llanl issue. This is due
to the desire--cr~ated by recent i"c,eases in aluminum Dl can production levels
--to suL,slantially raise the aluminum Dl can manufacturing speed and the de-
sire to reduce the size of surface l, ~dtl "enl facilities in order to cGnsel ~/e space.
The surfaces of aluminum Dl cans at presenl are l,eated mainly with
ph os~Jhoric acid cl "o",dte lledtlllel ,l baths and zirconium-containing non-chrom-
ate lreal",enl baths. The outside bottom surface of a Dl can body is generally
not painted during the aluminum Dl can manufacturing process but is subjected
to high-temperature sterilization. If its c~" uSiOI1 resislance is poor the aluminum
will beco",e o~ ed at this point and a blackening discoloraliûl, will occur. This
phenomenon is generally known as "blackening". It is for this reasGn that the
(unpainted) coating produced by surface l~t:at",ent must itself exhibit a high cor-
rosion resistance.
WO 9S/25831 2 1 8 6 ~ 2 ~ PCT/US95/03192
-
The lredt~ent Ill~thod taught in Japanese Patent Application Laid Open
[Kokai or Unexamined] Number Hei 1-246370 1246 370/1989] is one example of
an invention directed at sho,taning the surface Ireat",e"l time under considera-tion. In this method the surface of the aluminiferous metal is first cl.~a"ed with
5 an alkaline deylaaser and the clea"ed surface is tl ,er~er ~,~aled with an acidic
solution (pH = 1.5 to 4.0) containing 0.01 to 0.5 g/L of zirconium ions 0.01 to 0.5
g/L of pl ,osphale ions and 0.001 to 0.05 g/L of effective F ions and optionally0.01 to 1 g/L of vanadium ions. This method however does not afford an indus-
trially sati-~ractory blackening resisla"ce.
A non chron)ale l,~dt",enl " lethod is lisclosed in Japanese Patent Publi-
cation Number Sho 57-39314 [39 314/1982]. In this Illetllod the surface of
aluminiferous metal is treated with an acidic solution containing titanium salt and/
or zirconium salt hydrogen peroxide and ,chos,c hol ic acid and/or condensed
phos,cl,o,icacid. Thisl,edt",e"lbathis however unstable anditalsoexhibits
~5 an ul,.s~3licr~toly reactivity in terms of surface film for",dtion. Nor does this dis-
closure specifically desuibe the l,~dt",enl te""~eralure lreal",enl time or treat-
ment pr~cess. Finally it is difficult to obtain an industrially stable blackening re-
sisla"ce using the Ill~t hod ~;sclosed in Japa"ese Patent P~ lic~liGn Number Sho57-3931 4.
20 Disclosure of the Invention
Problems to Be Solved by the Invention
The presenl invention seeks to solve the problems desc, ibed above for
the prior art. In speci~c terms, the present invention introduces a stable compo-
sition for l,adling the surface of aluminiferous metals that is able to rapidly impart
25 an excellent co"osion resi~lance and paint ad herel ,ce to the surface of aluminif-
erous metals. This invention also introduces a surface treatment r"etl ,od that
uses said colllposilion.
Summary of the Invention and Description of rlarer,ad EmbGdi",enls
The ,t,rase, ll inventors discovered that a very co" usio"-rasistant and high-
30 Iy paint-adl ,erent codling could be rapidly formed on the surface of aluminiferous
metal by exe~J~ion of a surface l,aal",enl method cor"~l ising (a) contacting the
aluminiferous metal surface prererably at 30 C to 50 C with an ~ueo!ls
WO 95/25831 PCT/US95103192
21 86025
surface lred~" ,en~ co",position, also called a "bath" for brevity even though it can
be used for spraying as well as i",r"er~ion said bath co",,urising preferably
consisli"~ esse, Itially of or more preferably cGnsisli"~ of water and a mixturein speciric p, opo, lions of phosphdte ions zirconium cor"~,ound fluoride and oxi-
5 dant (b) then rinsing the t,t atment bath-bea,ing surface of the metal with water
and (c) drying by heating. The pr~senl invention was acl ,.eved based on this dis-
covery.
The bath according to the present invention for treating the surface of
aluminiferous metals ;l ,ar~ute(istically co,,,,ul ises 1 to 80 parts by weight (here-
10 inafter usually abbreviated "pb~t') of phospi)ale ions zirconium co",pound at 1to 15 pbw as zirconium atoms fluoride at 3 to 100 pbw as fluorine atoms and 1
to 100 pbw of oxidant.
The Illethod according to the presenl invention for treating the surface of
aluminiferous metals ;l ,ar~.1eri~lically co" ,~.rises cGntauti"g the surface of alum-
15 iniferous metal for 2 to 30 seconcls at 30 C to 50 C with a surface lred~",ent
bath containing the above~es~ibed surface lr~dt",ent co",position then rinsing
the t, ealed metal surface with water and theredrler drying by heating.
The surface l,~dlmenl composition according to the present invention is
an acidic aqueous treatment bath whose essenlial ingreu;~nt is a mixture of
20 phosphate ions zirconium compound fluoride and oxidanl. Of particular import-ance is the joint use of fluoride and oxidanl in the surface l, ed~ el ll CO mposilio n
according to the present invention and the surface treatment bath used by the
surface l,edt",ent method accordir,g to the present invention. This joint use offluoride and oxicla, d has the su, ~, ising effects of ~labili~iny the surface t, eat" ,enl
25 bath and inducing a suL,~l~l Itial improvement in both the co"osio" r~sisldnce (re-
sistance to blackening) and paint adl ,erence of the resulting surface coaling.
The surface l,eal",enl composition according to the present invention is
an ~ueous bath of a mixture that contains the following col",l~onenls in the fol-
lowing weight proportions:
phospl ,ale ions 1 - 80 pbw
zirconium cor"pound (as zirconium atoms) 1 - 15 pbw
fluoride (as fluorine atoms) 3 - 100 pbw
wo 95n5831 2 1 8 6 0 2 5 PCT/US95/03192
oxidant 1 - 100 pbw
Its ge"eral ?H range is 1.0 to 4Ø
FY.eu~tion of the ,netl,od according to the present invention requires the
pr~pa,alio" of a surface t,eat",ent bath (~queo~s solution) containing the above-
5 desuiL,ed surface Lledtlllelll co"~posilioll. This preparation is preferably carried
out so as to give the following concenlrations for the various co",ponents in the
subject surface l,edt",ent bath.
pl,ospl,dle ions 0.01 - 0.8 g/L
~irconium compound (as ~ cor,ium atoms) 0.01 - 0.15 g/L
o fluoride (as fluorine atoms) 0.03 - 1 g/L
oxidant 0.01 - 1 g/L
The pH of this surface treatment bath is preferably adjusted into the range from2.0to4Ø
rl ,ospl)oric acid (H3PO4) its salts and the like can be used to introduce
pl ,ospl,dte ions into the surface l,eat",enl composition according to the present
invention. The pl ,ospl ,dte ions co, Ite"l in the above-desu ibed co""~onenl recipe
for the surface l,edt",enl co",posilion according to the prese, ll invention ral ,yes
from 1 to 80 pbw while the prerer,ecJ range is from 3 to 20 pbw. The corre-
sponding surface l(eat,ne,)l bath is poorly reactive and good film fo""alion does
not usually occur when the phosphale ions conlent in the above-des~, ibed com-
ponenl recipe falls below 1 pbw. While a good-quality film can be formed at
above 80 pbw the effect from the phospl ,ale ions is saturated at such levels
which are ll,er~rore unecGno,nical since they serve only to raise the cost of the
treatment bath.
The source of the zirconium compound in the surface lreatn~enl composi-
tion according to the preselll invention is not critical and the oxides hydroxides
r,itlales fluorides and the like of ~irconium can be used as the irconium com-
pound source. The zirconium compound conlenl in the above-desc, iL,ed com-
ponent recipe for the surface l,edt",enl composition according to the present in-
vention ranges from 1 to 15 pbw as zirconium atoms while the prerer, e-J zircon-ium compound coulel~l ranges from 4 to 8 pbw as ~;ICGI ,ium atoms. The cor-
responding surface lledtl "enl bath will not form a good-quality film when the zir-
WO95/25831 2 1 8 6 0 2 5 PCT/US95/03192
conium conlenl falls below 1 weight part. The quality of the film no longer im-
proves at amounts in excess of 15 pbw and such levels are lher~ore uneconom-
ical since they serve only to raise the cost of the ll edt"~e"t bath.
The fluoride source for the surface l,~dt",ent co",position according to the
5 pr~senl invention is not critical and acids such as hydrofluoric acid (HF) fluozir-
conic acid (H2ZrF6) fluotitanic acid (H2TiF6) fluosilicic acid fluoboric acid and
the like and the salts of these acids may be used as the fluoride source. The
fluoride contenl in the above-described cor"ponent recipe for the surface treat-ment wrnposition according to the preser,t invention ranges from 3 to 100 pbw
o as fluorine atoms. The preferred fluoride conlent ranges from 3 to 60 pbw as
- fluorine atoms. The co" ~s~ onding surface lreat"~enl bath is poorly reactive and
good film ro""dtion does not occur when the fluoride contenl falls below 3 pbw.
The use of amounts in excess of 100 pbw is undesirable be~ se the corre-
sponding inuease in metal etching c~uses a degraded appearance. The treat-
s ment bath requires the p,~sence of the fluoride in order to stabilize--as alumin-
um fluoride--the aluminum that elutes into the treatment bath. As a result the
G~timal fluoride content in the surface lredl" ,e"t bath used by the method of the
prese, ll invention will vary as a function of the conce, Itl alion of aluminum eluting
from the metal workpiece. For example the fluorine concenl,ation must be
20 appr~,ti",ately 0.2 g/L when the aluminum conce, Itldtion in the surface lredt",ent
bath is 0.1 g/L.
The type of oxidanl in the surface l,eat")ent co",posilion accordi"g to the
present invention is not critical. Useable oxidants include h~drùge,) peroxide;
acids such as nitrous acid tungstic acid molybdic acid peroxo acids such as
2s pe,u,cophosphoric acid etc.; salts of the preceding acids; and the like. Hydrogen
perùxide is the most prefer, ed oxidant based on the ease of waste water treat-
ment after use of a surface treatment bath conlaining subject co" ,position. Thefunction of the oxidant in the surface t,edt",ent co",posilion and lrealment meth-
od according to the pr~senl invention is to accelerate the reaction rate for zirconi-
30 um film formation on the metal surface. The oxidant conlenl in the above-de-
s~ ibecl component recipe for the surface tlt:dtlllent co"~position according to the
presenl invention ranges from 1 to 100 pbw. The pr~, red oxidant content rang-
W095/25831 2 1 8 6 02 5 PCT/US95/03192
es from 20 to 50 pbw. When the oxidant cGnlenl is less than 1 pbw, the above-
des~iL,ed r~ution accelo,ating activitywill not be observed when surface treat-
ment is carried out using the co" espunding surface t, ~dtl nent bath. Although no
technical problems are ~ssoci~tecl with levels in excess of 100 pbw, the effect of
5 this co"~pone"l is saturated at such levels and they are li.erefore u"econo",ical,
bec~use they serve only to raise the cost of the lreal",enl bath.
The general range for the pH of the surface l,edb"e, n co",posilion accord-
ing to the present invention is 1.0 to 4Ø The surface Ir~dt",enl bath used by the
rn~thod accordi. ,9 to the present invention prererably has a pH of 2.0 to 4Ø pH
o values below 2.0 often cause an .o,~cessive etch of the metal surface and can im-
pede ro""dtion of the conversion film. Values in excess of 4.0 will in some cases
impede the ro""dtion of a highly col,osion-resi~lant film. The range of 2.3 to 3.0
is an even more prerer~ed pH range for the surface Ireat",e,)t bath used in the
rllethod according to the present invention. The pH of the surface treatment bath
5 can be adjusted in the ",ethod according to the prese"l invention through the use
of acids, such as phospho, ic acid, nitric acid, hydrochloric acid, hydrofluoric acid,
etc., or through the use of alkali, such as sodium hydl oxide, sodium csrL,onate,
ammonium hydroxide, etc.
When the metal treated by the "~ethod according to the presenl invention
20 iS an alloy of aluminum with, for example, copper, n,snganese, etc., the stability
of the treat",enl bath can be sul,slantially impaired by elution into the surface
l, eat" ,enl bath of metal ions deriving from the copper"nanganese, etc., compon-
ent of the aluminum alloy. In cases such as this, an organic acid, such as glu-
conic acid, oxalic acid, etc., may be added to the surface lreal,nent bath in order
25 to chelate this metal alloying co"~po"enl.
The details of the surface treatment Illethod accordi"g to the present in-
vention will now be explained. The method accordi"g to the present invention
uses a surface treat" ,ent bath according to the present invention. When the sur-
face Lledllllent bath takes the form of a concent~dle, it is diluted with water to the
30 desired concent, dliol, prior to use in the method according to the present inven-
tion.
WO95/25831 2 1 8 6 ~25 PCT/US95/03192
Prefer,ed ex~.ar,ded surface t~eal",enl process steps:
(1) Surface cleaning: degreasing--an acidic alkaline or solvent-based
degreaser may be used
(2) water rinse
s (3) characte,i~lic surface l(eal",e,)t (application of a surface treatment bath
according to the present invention)
treatment te"~perat-lre: 30 C to 50 C
treatment method: immersion or spraying
l,eal",enl time: 2 to 30 seconds
10 (4) water rinse
(5) rinse with de-ionized water
(6) drying
Contact betwccn the metal and surface treatment bath preferably is car-
ried out at 35 C to 50 C in the surface ll eat" ,e, ll method according to the pres-
~s ent invention. Contact ter"~r~tures below 35 C so" ,eti" ,es result in in~de~u~te
reaction between the metal surface and l,eat,nent bath which prevents the
~ol " ,a~ion of a good~uality film. The zirconium co" ,pound in the treatment bath
may become unstable at lel "per~lures above 50 C with the undesirable result
that a portion of the ~i~on. ~m col"pound will precipitate.
The method according to the presenl invention can be executed by im-
mersing the metal in the surface t(eal",enl bath in which case the i"~mersion
ll t:dtlllenl time pr~rdbly should be 2 to 30 seconds. I",r"ersion times below 2seconds usually result in in~de4u~te rea~;tion between the treatment bath and
metal surface which prevents the formation of a film with good corrosion resist-ance. h"(ner~ion times in excess of 30 seconds do not normally yield any addi-
tional improver"enl~ in the prope~ lies of the resulting conversion cGalings. Thus
pr~"~d immersion l,edl",enl times range from 2 to 30 seco,lds while immer-
sion times ranging from 5 to 15 seconds are more particularly prefe" ed.
Contact may also be exec~ lted in the " ,ell ,od accorcJing to the present in-
vention by spraying the treatment bath onto the metal surface. The occurrence
of a pH increase in the vicinity of the inlel race with the metal surface may be-
come ~.rot,e.r,dticwhen spray treatment is carried out by continuously spraying
WO 95/25831 2 1 8 6 0 2 5 PCI/US95/03192
the lleat",ent bath and in some cases a sdtisracto~ film ro""dtion will not occur.
It is for this reason that use of an inle" "illenl spray is pr~" ed. Said intermittent
spraying pr~rerably consials of at least two sprays separated by an interval of 1
to 5 secGnds. The surface l, edt" ,enl bath/metal surface conlact time (sum of the
spray and non-spray time intervals) in this case should again range from 2 to 30seconds. Contact times below 2 seconcls often result in an i"Adequ~te reaction
and prevent the rolllldlion of a film with good co"osion r~sialance. No additional
improvement in pe,ro~"ance is normally oblai"ed for contact times in excess of
30 seco, Ida. Spraying at least twice with separalion by an interval of 2 to 3 sec-
o onds is a particularly pr~rerred ~echniq.le and the prefer,ed overall contact time
is 5 to 10 seconds.
The add-on of the surface coating formed on aluminiferous metal by the
invention n,etl,od is pr~rer~bly 7 to 18 mg/m2 as zirconium. An in~dequ~te corro-
sion resistance by the resulting surface coating may result when the surface
coating weight is less than 7 mg/m2 as zirconium. The paint a.ll ,erence of the re-
sulting surface coating will in some cases be unsatisfactory when the surface
coati"y weight exceeds 18 mg/mZ as zirconium.
The aluminiferous metals whose surface may be treated by the invention
",etl,od enco",pass aluminum and aluminum alloys wherein the aluminum alloys
are exemplified by Al-Mn alloys Al-Mg alloys Al-Si alloys and the like.
The aluminiferous metal that may be subjected to the invention method
is not specirically resl,icted with r~spect to shape or dime"sions and for examp-
le sheet various types of moldings and the like may be subjected to the method
according to the present invention.
The surface l,edt",enl cor,~posilion and surface l,~l",ent method accord-
ing to the pr~senl invention are further illusll dted by the following working examp-
les and the benefits of the invention may be further appreciated by comparison
to the co",parisG" examples.
Examples
(1 ) Specimens
Aluminum Dl can (rab, icaled by the Dl processing of aluminum sheet) was
cleaned with a hot aqueous solution of an acidic degreaser (PALKLINTM 500
WO 95/25831 - 2 1 8 6 0 2 5 PCT/US95/03192
r~g;sler~d l,ddema,k of Nihon Parke(i~i"g Company Limited) and then subjected
to surface l,eal,nenL
(2) Evaluation Methods
la) Corrosion resislance
The corrosion resislance of the aluminum Dl can was evaluated based on
the ,~sia~nce to blackening by boiling water. The boiling water blackening re-
sislance was deter",ined by immersing the surface-lreated aluminum Dl can in
boiling tap water for 30 minutes and then visually evaluating the extent of discol-
oration (blackening) thereby produced The results of this test are repo,led on
.o the following scale:
+ : no blackening
x : partial blackening
x x : blackening over entire surface
Paint adherence
The surface of the surface-treated aluminum can was coated to a paint
film thickness of 5 to 7 micr~r"ete, ~ with an epoxy-urea can paint. This was fol-
lowed by baking for 4 minutes at 215 C. A 5 mm x 150 mm strip was then cut
from the painted can and polyamide film was hot-press bonded at 200 C to the
painted surface of the strip to give a test spec;",e". The test speci",en thus pre-
pared was subjected to a 180 peel test in which the peel sl, t:"lyth was measured
during peeling of the polyamide film from the test spec;",en. Higher peel sl,~ Jt h
values in this test are indicative of a better paint adl ,erence by the surface-treat-
ed aluminum can and peel slrengll, values equal to or y,eater than 4.0 kilo-
grams-force per 5 milli",eters of width (hereinafter usually abbreviated "kgf/
5mm") are generally regar~led as satisfactory for practical applications.
Example 1
A clea.led aluminum Dl can as des~ ibed above was sprayed with surface
l,eatment bath 1 (with a composition given below) heated to 40 C. This spray
l,~dt",ent consisled of 3 sprays (2 seconds each) separaled by 3 second inter-
vals (for a total of 12 seconds). The treated surface was then rinsed with tap
water and thereafter sprayed for 10 seconds with de-ionized water (with a resis-tivity of at least 3 000 000 ohm-cm). The aluminum Dl can was s~ ~hseguently
WO9St25831 2 1 8 6 0 25 PCT/US9S/03192
dried in a hot-air drying oven at 180 C for 2 minutes and sulJIllitled to evaluation
of the corrosion resista"ce and paint adherence.
Composition of surface lreat",en~ bath 1 ('ppm" hereinafter means parts per
million by weight)
75 % phosphoric acid (H3PO4) 69 ppm (PO4ions: 50ppm)
20 % fluo~ir~nic acid (H2ZrF6) S00 ppm (Zr: 44 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 95 ppm)
30 % hydrogen peroxide (H2O2) 322 ppm (H2O2: 100 ppm)
pH: 3.0 (adjusted with aqueous ar"",onia)
,0 Example 2
A cleaned aluminum Dl can was i"""ersed for 15 seconds in surface
treatment bath 2 (with a composition given below) heated to 50 C. The Dl can
was removed from the surface t,adt",enl bath and then rinsed with water rinsed
with cieior,i~ed water and dried according to the procedure in Example 1. The
.5 resulting Dl can was suL""itled to evaluation of the co,,usion r~sisla"ce and paint
adherence.
Composition of surface l,eal",enl bath 2
75 % phûsphoric acid (H3PO4) 69 ppm (PO4ions: 50ppm)
20 % fluo~ifconic acid (H2ZrF6) 1000 ppm (Zr: 88 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 150 ppm)
30 % hydrogen peroxide (H2O2) 166 ppm (H2O2: 50 ppm)
pH: 3.3 (adjusted with aqueous a"""onia)
Example 3
A cleaned aluminum Dl can was sprayed with surface treatment bath 3
2s (with a cor,lposilion given below) heated to 50 C. This spray treatment consist-
ed of 2 sprays (2 seconds each) separated by a 1 secc,nd interval (total of 5 sec-
onds). This was followed by rinsing with water rinsing with deionized water and
drying according to the procedure in Example 1. The resulting Dl can was sub-
jected to evaluation of the corrosion resistance and paint adherence.
30 Composition of surface treatment bath 3
75 % phos,cl)o,ic acid (H3PO4) 14 ppm (PO4ions: 10ppm)
20 % fluo~irconic acid (H2ZrF6) 1000 ppm (Zr: 88 ppm)
WO 95/25831 2 1 8 6 0 2 5 PCT/US95/03192
20 % hydrofluoric acid (HF) 210 ppm (F: 150 ppm)
30 % hy.J~ogen peroxide (H2O2) 1660 ppm (H2O2: 500 ppm)
pH: 2.5 (adjusted with sodium hydroxide)
Example 4
s A cleaned aluminum Dl can was sprayed with surface l,eal,nenl bath 4
(with a compositio" given below) heated to 50 C. This spray treatment consisl-
ed of 6 sprays (3 seconds each) sepa, aled by 2 seco"d inte~als (total of 28 sec-
onds). This was followed by rinsing with water rinsing with deionized water and
drying according to the pr~cedure in Example 1. The resulting Dl can was sub-
o mitted to evaluation of the corrosion resistance and paint adherence.
Composition of surface treatment bath 4
75%phosphoricacid(H3PO4) 138ppm (PO4 ions: 100
ppm)
20 % fluozirconic acid (H2ZrF6) 250 ppm (Zr: 22 ppm)
20 % hydrofluoric acid (HF) 100 ppm (F: 47 ppm)
30 % hydrogen peroxide (H2O2) 830 ppm (H2O2: 250 ppm)
pH: 4.0 (adjusted with ~gueous a,n")onia)
Example 5
A cleaned aluminum Dl can was sprayed with surface l,eal",e"l bath 5
20 (with a co" ,position given below) heated to 35 C. This spray treatment consisl-
ed of 3 sprays (2 seconds each) separdted by 2 second intelvals (total of 10 sec-
onds). This was followed by rinsing with water rinsing with deionized water and
drying according to the pr~cedure in Example 1. The resulting Dl can was sub-
jected to evaluation of the corl osion resistance and paint adl ,erence.
Composition of surface l,eal",ent bath 5
75 % phospl ,oric acid (H3PO4) 138 ppm (PO4 ions: 100
ppm)
20 % fluozirconic acid (H2ZrF6) 500 ppm (Zr: 44 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 95 ppm)
30 % hyd,ogen peroxide (H2O2) 322 ppm (H2O2: 100 ppm)
pH: 2.0 (adjusted with aqueous am",onia)
Example 6
WO95/25831 2 1 86025 PCT/US95/03192
A cleaned aluminum Dl can was sprayed with surface treatment bath 6
(with a c~",position given below) heated to 35 C. This spray treatment ~r,sisl-ed of 3 sprays (3 seconds each) sepdldted by 5 second intervals (total of 19 sec-
onds). This was followed by rinsing with water rinsing with deionized water and
5 drying according to the pr~.cedure in Example 1. The resulting Dl can was sub-jected to evaluation of the corrosion resistance and paint adherence.
Composition of surface l,edl",enl bath 6
75 % phosph~, ic acid (H3PO4) 69 ppm (PO4ions: 50 ppm)
20 % flu~ir~nic acid (H2ZrF6) 500 ppm (Zr: 44 ppm)
0 20 % hydrofluoric acid (HF) 210 ppm (F: 95 ppm)
sodiumtungstate(Na2WO4 2H2O) 1000ppm (WO4: 800ppm)
pH: 2.5 (adjusted with nitric acid)
Example 7
A cleaned aluminum Dl can was sprayed with surface l,eal",ent bath 7
s (with a co"~posili~" given below) heated to 35 C. This spray treatment consist-
ed of 4 sprays (2 seconds each) sepa,a~d by 2 second intervals (total of 14 sec-onds). This was followed by rinsing with water rinsing with deionized water and
drying according to the pr~Jcedure in Example 1. The resulting Dl can was sub-
jected to evaluation of the corrosion resistance and paint adherence.
C~",~osilion of surface l,e~t,nenl bath 7
75 % ,c I ,osph~ric acid (H3PO4) 69 ppm (PO4ions: 50 ppm)
20 % fluo~irconic acid (H2ZrF6) 500 ppm (Zr: 44 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 95 ppm)
20 % sodium nitrite (NaNO2) 1000 ppm (NO2: 133 ppm)
pH: 2.5 (adjusted with nitric acid)
Example 8
A cleaned aluminum Dl can was sprayed with surface l~edt",enl bath 8
(with a CGI,~ osition given below) heated to 35 C. This spray lreal",enl consist-
ed of 3 sprays (2 seconds each) separ~ted by 2 second intervals (total of 10 sec-
30 onds). This was followed by rinsing with water rinsing with deionized water anddrying according to the prl,ce.lure in Example 1. The resulting Dl can was sub-
jected to evaluation of the corrosion resistance and paint adherence.
WO 95/25831 2 1 8 6 0 2 5 PCI/US95/03192
Co"lposi~ion of surface treatment bath 8
75%pl,0spl,0ricacid(H3PO4) 690ppm (PO4 ions: 500
ppm)
20 % fluo~irconic acid (H2ZrF6) 500 ppm (Zr: 44 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 95 ppm)
30 % hydroyen peroxide (H2O2) 166 ppm (H2O2: 50 ppm)
pH: 3.0 (adjusted with nitric acid)
Example 9
A cleaned aluminum Dl can was sprayed with surface lleatlllenl bath 9
.0 (with a composition given below) heated to 35 C. This spray treatment consist-
ed of 3 sprays (2 seconds each) separ~ted by 2 second intervals (total of 10 sec-
onds). This was followed by rinsing with water, rinsing with deionized water, and
drying accor~ing to the pr~cedure in Example 1. The resulting Dl can was sub-
jected to evaluation of the corrosion resistance and paint ad here"ce.
Composition of surface lrealmenl bath 9
75 % phosphoric acid (H3PO4) 25 ppm (PO4ions: 18ppm)
2o%fluo~ilcollicacid(H2zrF6) 228ppm (Zr: 20ppm)
20 % hydrofluoric acid (HF) 150 ppm (F: 54 ppm)
30 % hyc3rogen peroxide (H2O2) 667 ppm (H2O2: 200 ppm)
pH: 2.5 (adjusted with aqueous a",mGnia)
Example 10
Acl~aned aluminum Dl can was sprayed with surface lredt",enl bath 10
(with a co"~po~ition given below) heated to 35 C. This spray treatment consis~-ed of 7 sprays (2 seconds each) separdted by 2 second intervals (total of 30 sec-
onds). This was followed by rinsing with water, rinsing with deionized water, and
drying according to the pf~ccdure in Example 1. The resulting Dl can was sub-
jected to evaluation of the corrosion resistance and paint adherence.
Composition of surface treatment bath 10
75 % phosphoric acid (H3PO4) 14 ppm (PO4 ions: 10 ppm)
20 % fluo~irconic acid (H2ZrF6) 114 ppm (Zr: 10 ppm)
20 % hydrofluoric acid (HF) 150 ppm (F: 41 ppm)
30 % hyd~ uyen peroxide (H2O2) 3333 ppm (H2O2: 1000 ppm)
14
WO95/25831 2 1 8 6 ~2 5 PCT/US95/03192
pH: 2.8 (adjusted with aqueous a"""onia)
Example 1 1
A cleaned aluminum Dl can was sprayed with surface tre~t",ent bath 11
(with a co",position given below) heated to 35 C. This spray Ll eal",el)t consist-
5 ed of a 3-second spray (total of 3 seconds). This was followed by rinsing withwater rinsing with deioni ed water and drying according to the procedure in Ex-
ample 1. The resulting Dl can was subjected to evaluation of the corrosion re-
sista"ce and paint adl ,erence.
CG""~osilion of surface treatment bath 11
o 75 % phosphoric acid (H3PO4) 413 ppm (PO4: 300 ppm)
20 % fluo~irconic acid (H2ZrF6) 1706 ppm (Zr: 150 ppm)
20 % hydrofluoric acid (HF) 150 ppm (F: 216 ppm)
30 % h~,drogen peroxide (H2O2) 16667 ppm (H2O2: 5000 ppm)
pH: 2.5 (adjusted with ~ueo!~s a"""onia)
Comparative Example 1
A cleaned aluminum Dl can was sprayed with surface l,~:al",enl bath 12
(with a cornposilion given below) heated to 35 C. This spray tredt"~e"l consisl-
ed of 3 sprays (2 seconds each) separdted by 2 second intervals (total of 10 sec-
onds). This was followed by rinsing with water rinsing with deionized water and
20 drying according to the p,~cedure in Example 1. The resulting Dl can was sub-jected to evaluation of the corrosion resislance and paint adl ,erence.
Co"")osilion of surface lreal",enl bath 12
75 % phospl,oric acid (H3PO4) 69 ppm (PO4ions: 50ppm)
20 % fluo~irconic acid (H2ZrF6) 500 ppm (Zr: 44 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 95 ppm)
pH: 3.0 (adjusted with aqueous ~"lmonia)
Co",paralive Example 2
A cleaned aluminum Dl can was sprayed with surface treatment bath 13
(with a composi~ion given below) heated to 35 C. This spray treatment consist-
ed of 3 sprays (2 seconds each) sepdr~ted by 2 seconcl intervals (total of 10 seG
onds). This was followed by rinsing with water rinsing with deionized water and
drying according to the ~urocedure in Exa",ple 1. The resulting Dl can was sub-
WO 9S/25831 2 1 8 6 0 2 5 PCT/U~95~'~,3192
jected to evaluation of the corrosion resistance and paint adherence.
CGmposilion of surface lrealn~enl bath 13
75 % phosphoric acid (H3PO4) 69 ppm (PO4ions: 50 ppm)
20 % fluo~irco"ic acid (H2ZrF6) 57 ppm (Zr: 5 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 40 ppm)
pH: 3.0 (adjusted with aqueous a",r"Gnia)
Comparalive Example 3
A claaned aluminum Dl can was sprayed with surface treatment bath 14
(with a co",posilion given below) heated to 35 C. This spray treatment consist-
0 ed of 3 sprays (2 seconds each) separ~ted by 2 second intervals (total of 10 sec-
onds). This was followed by rinsing with water rinsing with deionized water and
drying according to the pr~cedure in Example 1. The resulting Dl can was sub-
jected to evaluation of the corrosion resislal ,ce and paint adherence.
Composition of surface treatment bath 14
20 % fluo~irco,)ic acid (H2ZrF6) 500 ppm (Zr: 44 ppm)
20 % hydrofluoric acid (HF) 210 ppm (F: 95 ppm)
pH: 3.0 (adjusted with aqueous ammonia)
Col"paralive Example 4
A claaned aluminum Dl can was sprayed with a co" " "ercial aluminum Dl
20 can surface ll~dtll~el)t bath (ALODINETM 404 reg;sler~d l,d.len)a,k of Nihon Par-
keri~ins~ Co"~pany Limited) heated to 30 C. This spray treat",enl cGnsisled of
3 sprays (2 seconds each) sepal ~ed by 2 second intervals (total of 10 seconds).This was followed by rinsing with water rinsing with deionized water and drying
according to the procedure in Example 1. The resulting Dl can was subjected
25 to evaluation of the corrosion resistance and paint adl ,erer,ce.
The results of the evaluations for the cans treated in Examples 1 - 11 and
Comparison Examples 1 - 4 are all reported in Table 1.
As del"onslr~led by the results in Table 1 an excellent cor,osion resist-
30 ance and an excellent paint adherence were exhibited by the surface coatingsproduced in Examples 1 to 11 which employed surface treatment baths and sur-
face t,edt",e,lt metl,ods according to the pr~senl invention. Co",pa,dtive surface
16
WO 95/25831 2 1 8 6 0 2 ~ PCT/US95/03192
treatment baths were used in Comparative Examples 1 to 4 and the surface
coatings produced by these co",par~ti~e baths exhibited a poor corrosion resist-ance and sG",eli"~es a poor paint adherence.
Benefits of the Invention
As the preceding ~iscl ~ssion has made clear the surface lredlmenl bath
and surface ll t:atment "~ethod according to the present invention are able to rap-
idly produce highly corrosion-resistant and very paint-adherent CGdtil "~s on the
surface of aluminiferous metals prior to the painting thereof. When applied to
aluminum Dl cans the surface l,t:at"~enl bath according to the present invention.0 rapidly produces a very corrosion-resistant and paint-adherent coaling on the
surface of aluminum Dl cans prior to its painting or printing. This makes it possi-
ble to speed up the manufacturing line and reduce the size requirements (space
economization) of the treatment installation.
As a result of these features both the bath and method according to the
present invention for l,eali"g the surface of aluminiferous metals have a very
high practical utility.
W O 95/25831 PCTrUS95/03192
2 1 86025
Table 1.
5 Example or Resistance to Blackening Peel St,en,Jtll Zr Add-on
Comparison in Boiling Water kgf/5mm mg/m
Example No.
Example 1 + 4.0 10.5
Example 2 + 4.0 13.5
Example 3 + 4.0 7.5
Example 4 + 4.0 15.5
Example 5 + 4.0 12.2
Example 6 + 4.0 13.5
Example 7 + 4.0 11.0
Example 8 + 4.0 9.8
Example 9 + 4.0 8.2
Example 10 + 4.0 9.7
Example 11 + 4.0 8.5
Co"")arali~/e x 2.5 8.0
Example 1
C Olllpardli~e X X 4.0 3.0
Example 2
Comparative x x 4.0 6.5
Example 3
Co,nparali~e x x 2.0 6.0
Example 4
18
