Note: Descriptions are shown in the official language in which they were submitted.
21 87795
~WO 95/28509 r~.l,.J.. _. . _
Descrir tion
COhll~O~I I ION AND PROCESS FOR TREATING THE SURFACE OF
ALUMINIFEROUS METALS
Technical Field
This invention relates to a novel ~,,,uusi~iù,~ and method for treating the
surface of aluminiferous metals in order thereby to provide such surfaces, priorto their being painted, with an excellent corrosion resistance and paint adher-
s ence. This invention may be effectively applied, in~er alia, to the surface treat-
ment of drawn-and-ironed (h~l~il . '' usually abbreviated "Dl") aluminum cans.
Vvhen applied to the Dl aluminum cans fabricated by the drawing-and-ironing of
aluminum alloy sheet, the surface treatment culllluu~iliù~ and method according
to the present invention are particularly effective in proYiding the surface of such
cans, prior to the painting or printing thereof, with an excellent corrosion resist-
ance and paint adl,e,~:,-ce and also with the excellent ! ' '- ~ y required for
smooth conveyor transport of the can (dbLII ~ below simply as "~ ' '~ ' "~,:").
Bac~ round Art
Liquid cul ", ' ,~, which hereinafter are often called "baths" for brevity,
15 even though they may be used by spraying or other methods of ~a~dL~ 'ù
contact than immersion, that are useful for treating the surface of aluminiferous
metals, defined as aluminum and its alloys that contain at least 45 % by weight
of aluminum, may be broadly classified into chromate-type treatment baths and
non-chromate-type treatment baths. The chromate-type surface treatment baths
20 typically are divided into chromic acid chromate conversion treatment baths and
pl~u~l lU~iU acid chromate conversion treatment baths. Chromic acid chromate
conversion treatment baths were first used in about 1 95û and are still in wide use
at present for the surface treatment of, for example, heat t~ ,l Idl lu~l flns and the
like. Chromic acid chromate conversion treatment baths contain chromic acid
25 (CrO3) and hydrofluoric acid (HF) as their essential cu,,,,uul~l ,ts and may also
contain a conversion acc~l~, d~ul . These baths fomm a coating that contains small
amounts of hexavalent chromium. The ,ul lus~l ,u, iu acid chromate conversion
treatment bath was invented in 1945 (see U. S. Patent 2,438,877). This conver-
sion treatment bath contains chromic aud (CrO3), ~l ~o~,ul ,u, i~. acid (H3PO4), and
W095/28509 ' ' 2-l 8 7 7 9 5
hydrofluoric acid (HF) as its essential cu, ",uu,~ . The main c~" ,,uo,~e"~ in the
coatin3 produced by this bath is hydrated chromium ~.1 lo~,ul Idl~: (CrPO4 4 H20).
Sirlce this conversion coating does not contain hexavalent chromium, this bath
is still in wide use at present as, for example, a paint undercoat treatment for the
s lid and body of bevera3e cans.
The treatment bath tau~ht in Japanese Patent Application Laid Open [Ko-
kai or Ul leAdl l lil l~d] Number Sho 52-131937 [131,937/1977] is typical of the non-
chromate-type ~" /~. aiul I treatment baths. This treatment bath is an acidic (pH
= li~U~JI UA;I I Idtt5ly 1 .0 to 4.0) ;. ' IJUI I ~e coatin3 solution that contains pl~ospi ~dLt:,
0 fluoride, and zirconium or titanium or their compounds. Treatment of aluminifer-
ous metal surfaces with this non-ul " u" ' type conversion treatment bath pro-
duces thereon a conversion film whose main ,u",uoo~"1 is zirconium and/or ti-
tanium oxide. The absence of h~xavalent chromium is one advantage associat-
e~ with the non-chromate-type conversion treatment baths; however, the conver-
~s sion coatings produced by them in many instances exhibit a corrosion resistance
and paint adherence that is inferior to those of the coatings generated by chro-mate-type conversion treatment baths. Moreover, both chromate-type and non-
chromate-type cc " .~, aiul I treatment baths contain fluorine, which conflicts with
the cu"tt"",uu, d, y desire, prompted by envi, u"" ,e~ dl concerns, for the practical
il "~,le" ,c "~ iu" of fluorine-free surface treatment baths.
The use of water-soluble resins in surface treatment baths and methods
intended to provide aluminiferous metals with corrosion resistance and paint ad-herence is described, for example, in Japanese Patent Application Laid Open
[Kokai or Ul I~Adl l lil 113d] Numbers Sho 6191369 [91,369/1986] and Hei 1-172406
[1~2,406/1989], Hei 1-177379 [177,379/1989], Hei 1-177380 [177,380/1989], Hei
2~508 [608/1990], and Hei 2-609 [6û9/1990~. In these examples of the prior art
surface treatrnent baths and methods, the metal surface is treated with a solution
containing a derivative of a polyhydric phenol compound. However, the forma-
tion of an acceptably stable resin-containing coating on the aluminiferous metalsurface sometimes is highly ,u, u~l~, lldliu with these prior art methods, and they
do not always provide an aC~ l ,le p~ rul Illdl ,ue (corrosion resistance). The
invention described in Japanese Patent Application Laid Open [Kokai or Unex-
~W095/28509 2 1 8~1 9~
amined] Number Hei 4-66671 [66,671/1992] constitutes an improvement to treat-
ment methods that use polyhydric phenol derivatives, but even in this case the
problem of an ~I~s~ r~ l y a~ "-,e su" ,~i" ,~s arises.
The surface of Dl aluminum cans is at present treated mainly with the
above-described ~ul lua,ul ~u~ i~, acid chromate surfaoe treatment baths and zirconi-
um-containing non-chromate surface treatment baths The outside bottom sur-
face of Dl aluminum cans is not painted, but is subjected to high-temperature
sl~, i' " ,. If its corrosion resistance is poor, the aluminum will become oxi-
dized at this point and a blackening diawlOI d~iUI I will occur, a yl ,t:"u" ,~,u,, which
0 is generally known as "uldck~l ,i"u~". In order to prevent bldche l ,i"u, the coating
produoed by surfaoe treatment must itself, even when unpainted, exhibit a high
corrosion resistanoe.
Tuming to another issue, a high friction coefficient for the can's exterior
surfaoe will cause the can surfaoe to have a poor slideability during the conveyor
transport that occurs in the can rdL" iwliù,~ and finishing processes. This willcause the can to tip over, which will obstruct the transport process. Can trans-portability is a particular concern with regard to transport to the printer. Thus,
there is demand in the can fabrication industry for a lowering of the static friction
c~t:rricienl of the can's exterior surfaoe, which, however, must be achieved
zO without adversely affecting the adherenoe of the paint or ink which will be coated
on the can. The invention disclosed in Japanese Patent Application Laid Open
[Kokai or U, n3~dl l lil ,~d] Number Sho 64-85292 [85,292/1989] is an example ofa method directed to improving this slideability. This invention relates to a sur-
face treatment agent for metal cans, wherein said surface treatment agent con-
zs tains water-soluble organic substanoe selected from ~l lua,ul l.,h esters, alcohols,
monovalent and polyvalent fatty acids, fatty acid derivatives, and mixtures of the
preoeding. Vvhile this method does serve to increase the slideability of aluminum
cans, it affords no i" ,,u, u ~u. "t:"l in corrosion resistanoe or paint ddl 1131 c:,~ce.
The invention described in Japanese Patent A~, " " , Laid Open [Kokai
or U, IC:.~dl l lil l~d] Number Hei 5-239434 [239,434/1993] is another method direct-
ed to improving the slideability of aluminum cans. This invention is ,1 Idl d~ d
by the use of phosphate esters. This method does yield an improved slideability,
21 ~7795
W0 95/28509 I ~ u~
but asain it affords no improvement in corrosion resistance or paint a~l ,e, ~,~ce.
Disclosure of the Invention
prQblems tQ Be Solved by the Invention
The present invention is directed to solving the problems described above
for the prior art. In specific temms, the present invention introduces a ~,u" ,uosiliù"
and method for treating the surfar~e of aluminiferous metal which are able to pro-
vide the surface of aluminiferous metal with an exr ellent corrosion resistance and
paint adherence. When applied in particular to Dl aluminum cans, said cQmposi-
tion and method impart thereto an excellent slideability in cu" ,~i, IdliUI I with an ex-
cellent corrosion resistance and paint dull ,~ "-,e.
Details of the Invention. Includina Preferred C,,IL:,Odi,,,e,,l;, Thereof
It has been ~ound that the problems described above for the prior art can
be solved thrQugh the application of a specific type of surface treatment bath that
is prepared using a surface treatment C~ll.r "' , cQntaining specific plloaul Id~e
15 io~s, cu"~e~sed pl~o:,,ul ,~ ions, and water-soluble polymers with a specificstnucture. It was found that the ,, ' " , of this surface treatment bath to the
surface of aluminiferous metal will form thereon a very conrosion-resistant and
highly paint-adherent resin-containing coating. It was also found that dupl;~liul~
of said bath to Dl aluminum cdns fomms thereon a resin-containing coating that
7.0 exhibits an improved slideability in addition to an excellent corrosion resistance
and paint adherence. The invention was achieved based on these di~,o~ ies.
A cul l l,uù~ according to the present invention for treating the surface
of aluminiferous metal ,1 Idl dUlt~ comprises, preferably consists essential-
ly of, or more preferably consists of, water and, in parts by weight:
z~ (A) from 1 to 30 parts of phosphate ions;
(B) from 0.1 to 10 parts of cu"ulensed phosphate ions; and
(C) from 0.1 to 20 parts of water-soluble polymer cc,,rullllill~ with the
followlng gene~al formula (I)
21 87795
WO95/28509 F~~
.
OH
~H 2
X1_ _X2
~y 2
in which each of X1 and X2 i"de~"d~ ~ I;'y of each other and i, Idt:,u_l Id~ ly from
one unit of the polymer~ as I ~ Stz~ d by formula (I) above with the brackets
and the subscript n omitted, to another unit of the polymer ,t:,u,t:S~ a a hydro-
.s gen atom, a C1 to Cs alkyi group, or a C1 to Cs hydroxyalkyl group; each of yl
and y2 i"~pend~";'y of one another and i, Id~utll ,d~"~'y for each unit of the poly-
mer, ~,u, I:ae~ a hydrogen atom or a moiety "Z' which conforms to one of the
following fommulas (Il) and (Ill):
R1 R3
_CH 2--N ( ll ) _CH 2--N _R4 ( lll )
R 2 \R s
wherein each of Rl, R2, R3, R4, and Rs in fommulas (Il) and (Ill) i, Idt:,u~l)d~ ly
represents a C1 to C10 alkyl group or a C1 to C10 I ~Ydl UA~-~hYI group; the moiety
Z bonded to any single phenyl ring in the polymer molecule may be identicdl to
or may differ from the moiety Z bonded to any other phenyl ring in the polymer
molecule; the average value for the number of Z moieties sl Ih5titl ~tod on eachphenyl ring in the polymer molecule is from 0.2 to 1 .û; n, which may be referred
to ~ ,~, _i, Id~l'3( as "the average degree of pol~" "~ dliUI 1", has a value from 2 to
50; and each polymer molecule (I) must contain at least one Z moiety-sl Ihstit~ ~t~d
phenyl ring. This average value for the number of Z moieties s~ Ih5titl ~t~d on each
WO 95/28509 ~ 1 8 7 7 ~ ~ I ~ " u ~ ~o~
.
phenyl ring in the polymer molecules of total w,,,pu,~, ,l (C) is 1~ il IdrLtlr re-
ferred to as the average value for Z moiety s~ Ih~t~ tin~.
C~lllr " ,~ according to the invention as described above may be ei-
ther working w,, Ir "' la, suitable for directly treating aluminiferous metal sub-
6 strates, or they may be cu, ,~,1~, dtt: r~u", ' Ia1 which are useful for preparing
working cu,,,~,u~;iiu, ,~, usually by dilution of the w,)r~, ,' dlt7 cw",~osiLiu"s with
water, and optionally, adjustment of the pH of the resulting working cr," ,,uùsiliun.
A method according to the present invention for treating the surface of
aluminiferous metal ,1 Idl ~ I ia~ 'y comprises contacting the surface of alumin-
0 if erous metal with a surface treatment bath containing the above-desuibed sur-
face treatment w,,,,u~iliu,, according to the present invention, then rinsing the
treated surface with water, and subsequently drying the surface by heating. In-
C~ ly, in a method according to the present invention, the bath preferably
has a pH value of 6.5 or less, the total time of contacting the metal to be treated
preferably is From 5 to 6û seconds, and th~ temperature during its contact with
the aluminiferous metal being treated preferably is from 3û C to 65 C. The re-activity of the bath may be insufficient below 3û C, ~ i"~ the formation of
a good-quality film. While a good-quality coating is formed at temperatures
above 65 C, the higher energy costs for heating make such temperatures eco-
nomically ~" ~d_ ,i, dble. Coating formation may be inadequate and a highly corro-
sion-resistant coating may not be produced when the immersion time is less than
5 seconds. Long immersion times in excess of 6û seconds usually produce no
~dditional improvements in p~,ru""~"~ and are disfavored because of their
~dded expense.
The surface treatment method according to the present invention may be
il l l,ul~:~ 11~1 ,t~ by immersing the aluminiferous metal, preferably for 5 to 6û sec-
onds, in the above-desuibed surface treatment bath. The surface treatment
method aorording to the present invention may also be i" I,ult:l "~, It~d by spraying
the above-desibed surface treatment bath onto the surface of the aluminiferous
metal, preferably at least twice, and preferably with an nonspray interval of from
2 to 5 seconds between each period of continuous spraying and the next period
of continuous spraying if there is one. ~he occurrence of the pH increase in the
W0 951~8509 r ~
vicinity of the interface with the surface, which is required for proper coatingformation, is less reliable when spray treatment is carried out by continuously
spraying the bath, and in some cases a satisfactory film formation will not occur.
It is for this reason that use of an i~ " IL spray is preferred. The total of the
s spray and nonspray interval time periods preferably is from 5 to 60 seconds. The
reaction may be inadequate and a highly corrosion-resistant coating may not be
produoed when the total contact time is less than 5 seconds. Lengthy total con-
tact times in exoess of 60 seconds usually produce no additional improvements
in pel rul l l Idl l~ and are more expensive.
o A surfaoe treatment , " I according to the present invention is an
acidic aqueous solution whose essential illyl~di~l,la are pl~Oal~ll ' ion, con-
densed ~sl IOa,~ l Id~t: ion, and water-soluble polymer with the above-specifiedchemical structure.
Pl lualJI ,u, iu acid (H3PO4), sodium phosphate (Na3PO4), and the like can
be used as the souroe of the phosphate ion in the surfaoe treatment cc", I,uOaiLiul I
according to the present invention. The phosphate ion content in the above-de-
suibed fommulation ranges from 1 to 3û parts by weight (1~ i, IdrL~r often abbre-
viated "pbw"), while the preferred range is from 1 to 5 pbw. Reaction between
the surfaoe treatment bath and the metal surface will be insurficient and film for-
2~ mation often will be inadequate when the pl~CIa,ul ~b, ions content in the above-
described formulation is less than 1 pbw. While a good-quality film is formed with
more than 30 pbw of ~JI IOa,UI ~ ' ions, the high cost of the resulting treatment
bath makes such levels e.,u"u",i~"~ ~lld~aildule.
The cù, Id~l Iaed phosphate ions used in the present invention conform to
25 the general chemical formula H~p~ PpO(3p~ / where p l~,ul~atlllla a positive
integer that is 2 or greater and q rt:~., t,s , ILa a positive integer that is from 1 to
(p+1 ); examples are py, u,ul lua~JI l..te ions, tripolyul IOa~ .t~, ions, tetrapolyphos-
phate ions, and the like. Either the ,u"densed ~JI lua,ul~û~ic acid or its neutral or
acid salt can be used as the c~ncle, laed pl~oa~ dLt: ion source for the surface3C treatment ~ iti~" according to the present inYention. For example, any of
pyl ul~l lua,ul ~ol i~ acid (H4P2O~), disodium did~.id~j~ upl IOa,UI Id~-; (Na2H2P2O~), tri-
sodium acidp~" ulJI lua~ (Na3HP20,), and tetrasodium p~" upl IOa,ul '
w0 9s/28S09 ~ 1 ~ 7 7 9 ~ ",~ j . }~
(Na~P207), can be used as the source of the p~lu!lllua,~ t~, ions. The con-
densed phosphate ions content in the above-described formulation for the sur-
face treatment w,, Ir " I according to the present invention, measured as its
aluii,lliu~ , equivalent of c;",u'u'~ ionized ,,ù,~densed ~llua~lld,- anions
5 c,J,,~u,,,,i,,ytothefommulaPpOpp,1)~2)lwherepandqhavethesamemeanings
as above, ranges from 0.1 to 1û pbw, while the preferred range is from 0.5 to 3.0
pbw. Surface treatment baths prepared using less than 0.1 pbw cu,,dens~d
pl~a,UlldL~ ion in the above-described formulation usually have only a weak
etchin6 activity and provide inadequate film formation. On the other hand, at
10 more than 10 pbw the etching activity generated by the resulting surface treat-
ment bath is too strong, so that the film-fomming reactions are inhibited.
Polymer according to formula (I) with n less than 2 yields only an insuffi-
cient improvement in the corrosion resistance of the resulting surface coating.
The stability of the cwll,,a,uùr~i~,g surface treatment WlilUO_ ~iJII and surface
s treatment bath is s~"",li",~s inadequate and practical problems often ensue in
the case of polymer (I) with n greater than 50.
The presence of 6 or more carbons in the alkyl and hydroxyalkyl groups
I~s,ul~:a~ l by X' and x2 in formula (1) causes the resulting polymer molecule
to be bulky and produceâ steric hindran,,e. This usually interferes with the forma-
20 tion of the fine, dense coatings that exhibit excellent corrosion resistance.Polymer (I) contains the Z moiety as a substituent, and the average valuefor Z mûiety substitution for each phenyl ring in the polymer mûlecule must range
from 0.2 to 1Ø As an example, in a polymer with n = 10 that has 20 phenyl
rings, if only 10 of these 20 phenyl rings are s~ IhCtitl itAd by one Z moiety each,
25 the average value for Z moiety substitution for this polymer is then calculated as
follows: (1 x 10 ) / 20 = 0.5.
The polymer usually is insufficiently water soluble when the average value
for Z moiety c~ Ih~t~ is below 0.2; this results in an insuffidently stable sur-face treatment cu, "~"~,..t~ and/or surface treatment bath. When, on the other
30 hand, the average value for Z moiety c~ tiûn exceeds 1.0 (s~ Ihstitl ~tion of a
phenyl ring by 2 or more moieties Z), the resulting polymer becomes so soluble
in water that formation of an ~Pql I ' l~ protective surface film is impeded.
- ~77q~
~WO 95128509 ~ .11 U,.,_ '~q~
The alkyl and hydroxyalkyl moieties u"-,u" I,Ud~ d by R', R2, Rs, R4, and
R5 in formulas (Il) and (111) should contain from 1 to 1 û carbon atoms each. The
polymer molecule becomes bulky when this number of carbons exceeds 10; this
results in a coarse coating and thereby in an insufficient improvement in the cor-
s rosion resistance.
The content of water-soluble polymer (I) in the above-described formu-
lation for the surface treatment cul "uu~iliul~ according to the present invention
ranges from 0.1 to 20 pbw, whiie the range from 0.5 to 5 pbw is preferred. The
fommation of a coating on the metal surface by the ~" I:a,uùl Idil l~ surface treat-
o ment bath often becomes quite ,u, ubl~" Idti~ when the content of the water-solu-
ble polymer in the above-described fommulation is below 0.1 pbw. Values above
20 pbw are ecol,u", 'Iy ~l~dt~ d~le due to the increased cost of the surface
treatment ~, . ,~ ;l ;.," and surface treatment method.
The pH of the surface treatment .,u",~u~ according to the present
~s invention is not narrowly restricted, but adjustment of the pH to values no greater
than 6.5, more preferably alsb not less than 2.0, is generally preferred.
The method according to the present invention is il~,ul~ d by the
r ,~,ud, " I of a working surface treatment bath using the above-described sur-
face treatment cu" IlJuailiùn (generally by dilution of a .,u"~ " dil:: with water).
20 The pH of the working surface treatment bath at this point is adjusted if
necessary to values no greater than 6.5 and preferably to 2.0 to 6.5.
The polymer cu, If ul " ,i"~ to fommula (I) in the surface treatment bath has
a pronounced tendency to deposit or ,u,, , at a surface treatment bath pH
above 6.5; this results in an ~" lad~ rd~lul y stability and service life for the treat-
2s ment bath. When the pH is below 2.0, the surface treatment bath may etch themetal surface too severely, which can impair formation of the surface coating.
The pH of the surface treatment bath may be adjusted using an acid, e.g., phos-
phoric acid, nitric acid, h~dluul llùric acid, and the like, or by using alkali, e.g.,
sodium hydroxide, sodium carbonate, ammonium hydroxide, and the like. Hydro-
so fluoric acid may be used to adjust the pH when waste water treatment presentsno problems.
When the aluminum ions eluted from the aluminifer~ous metal being
-
W0 95/28509 2 1 8 7 7 9 5 r~
treated according to the invention mixes into the surface treatment bath, a pre-c~pitate may be produced in some cases due to the formation of a complex
between polymer (I) and the aluminum ions. An aluminum sequestrant is prefer-
ably added to the treatment bath in such cases. Suitable as said aluminum
5 sequestrant are, for example, ethylene diamine tetraaoetic acid, Cy-DTA, trietha-
nolamine, gluconic acid, heptogluconic acid, oxalic acid, tartaric acid, malic acid,
and ol~,dllu~ a~ llorlic acids, but the particular sequestrant selection is not
critical. Hydrofluoric acid may be used as the sequestrant when it presents no
problems for waste water treatment.
c A process according to the present invention preferably is performed by
cûntacting the surfaoe of aluminiferous metal with a surface treatment bath--
prepared as described above--at 30c C to 65 C for a total of 5 to 60 seconds.
The process then continues with a water rinse of the film formed on the metal
surface and drying by heating.
Problems with the coating can occur due to foaming of the surface
treatment bath when a spray treatment is used. The g~"~, dlion of foam and the
intensity of foaming strongly depend on the type of spray equipment and the
spraying conditions, and a defoamer is preferably added to the surface treatmentbath when a foaming problem cannot be ~d~ rdu~ul ily resolved by changes to the
zc spray equipment and/or conditions. Such factors as the type and dia~ si"~ lev-
el of the defoamer are not critical, provided that they do not impair the paint
adl ,e, t:nce ûf the resulting coatins.
A preferred method of fJle5,UdldliUII of a surface treatment Culll~OaiLiul~
~ccording to the present invention will now be briefly summarized. To prepare
25 thesurfacetreatmentuu",l,u,~;;ùn,thePI~ JII ionsand~,ull~ s~dphos-
phate ions are first made up in the above-described ~,, u~u, ~iu,~s and dissolved
with thorough stirring in the required amount of water according to the preceding
;fi~ 1 la. When the pH of the resulting solution exceeds 7, it is adjusted to
less than or equal to 7 using a suitable acid as described above. The water-solu-
~c ble resin specified by the invention is then added while stirring and completelydissolved, and the pH is adjusted to less than or equal to 6.5 as described above.
The coating fommed on the surfaoe of aluminiferous metal will now also be
2l ~77q~
~W095128509 r~.,-..
briefly diswssed. The coating formed by the surface treatment bath according
to the present invention is an organic-inorganic composite coating whose main
wl I l,uul 1~ a are phosphate salt and polymer (1). Etching of the metal surface by
the phosphate ions and co"d~ d phosphate ions causes a local increase in pH
5 to ocwr at the interface; this results in deposition of ~.1 ,o~JI IdL~ salt on the metal
surface. In addition, the chelating activity of the amino group in polymer (I) may
result in the formation of a ~UOII.Iilld~iUll compound with the fresh substrate
surface exposed by etching. The presence of cu"d~nse:d pl lo~,ul ,dLe ions in the
surface treatment bath is believed to promote formation of the polymer-metal co-
.0 ordination compound and ther~by maka possible stable fommation of the organic-
inorganic composite coating on th~ 3urface over a broad pH range.
An additional pOl~ dliul l of 'he polymer present on the surface can
be induced by heating the surface coa~ing aKer its formation. In specific cases
where an elevated corrosion resistance is required, the coating is preferably
heated in order to produce a higher molecular weight for the polymer on the
surface. Suitable heating conditions for this purpose are at least 1 minute and
at least 2û0 C.
Aluminiferous metal substrates that may be subjected to the method ac-
cording to the present invention comprise, for example, the sheet, bar, tube, wire,
20 and like shapes, of aluminum and its alloys, e.g., aluminum-" Id~ Iydl ~ese alloys,
aluminum-magnesium alloys, aluminum-silicon alloys, and the like. There are
absolutely no limitations on the dim~r~slons or shape of the aluminiferous metal.
The polymer ~",~ ", ~cwr5ing to the present invention may wntain
a preservative or antimold agent. 1 hose functiûn to inhibit putrefaction or mold
25 growth when the surface treatment bath is used ûr stored at low temperatures. Hydrogen peroxide is a specific example in this regard.
The following is a short diswssion of further details of a process of treat-
ing the surFace of aluminiferous metal using the surface treatment bath according
to the present invention. The process steps outlined below are a preferred ex-
30 ample of ll-r' " ~ of the surface treatment bath according to the present in- vention.
11
?~ ~7~9~
WO 9S/28509 r~,l,~.. ,.".
(1 ) Surface cleaning: ~ylt:dail ,~--an acidic, alkaline, or solvent-based de-
greaser may be used.
(2) Water rinse
(3) Film-forming treatment (surface treatment method according to the pres-
ent invention)
(4) Water rinse
(5) Rinse with de-ionized water
(6) Drying
The invention is iilustrated in greater detail below through working examp-
o les, and its benefits may be further c~,u, ~:~,idlt:d by contrast with the .u" I,Udl iaul I
examples. The individual surFace trea.ment bath cu,, ,~.u, ,c:, ,t~ and surface treat-
ment methods are, ~a~ ,'y descriDed in the working and w" I,Udl '- .1~ examp-
les.
~me ç~
16 Evaluation Methods
(1) Corrosion resistance
The corrDsion resistance of the unpainted parts of the Dl aiuminum cans
(resistance to ~Idl~ lil l9 by boiling water) was evaluated based on the degree
of diawlul _' I (bld~ J) after immersion of treated Dl aluminum cans in boil-
20 ing tap water for 30 minutes. The results of this test are reported on the followingscale:
+ : no blacker.il ,g
x : partial ~Idche,li,lg
x x : blach~"i"g over entire surface
~ pAir;t a~ll le~l 1711~3
The paint dd~ i ,ce was tested as follows. The surface of the treated
can was coated to a paint film thickness of 5 to 7 ",i.;,u",~ with an epoxy-
urea can paint. This was followed by baking for 4 minutes at 215 C. A 5 milli-
mater (l ,~, c:i, ,d~ler usually dul,, ~ .t~,d ''mm'') x 150 mm strip was then cut from
30 the painted can and hot-press bonded with polyamide film to give a test spec-imen. The test specimen thus prepared was subjected to a 180 peel test, during
which the peel strength was measured Higher peel strength values in this test
2l 87795
WO95/28509 P_l/~J.,,!;. ~
are indicative of a better paint d~ "ce, and peel strength values equal to or
greater than 4.0 kilograms-force per 5 n " "~ of width (he, t i, ldrl~r usually
dLJL~ 1 as "kyU0,lll"l") are generally regarded as excellent from the stand-
point of practical ,, ' " ,s.
S (3! Slideabjlity
The slideability was evaluated by measurin~ the static friction coefficient
on the outside surface of the can. Lower values for the static friction coefficient
are indicative of a better slideability, and values less than or equal to 1.0 are gen-
erally regarded as excellent.
.0 F~rnDIe 1
Dl aluminum cans fabricated by the Dl ~., uc~:s~ing of A3û04 aluminum
alloy sheet were cleaned by first rlrzy, ~dai"y with a 6û-second spray at 75 C of
an 8 % aqueous solution of PALKLINTM 500 acidic degreaser manufactured by
Nihon Parkerizing Companyl Limited and then rinsing with water. The cleaned
s surface was subsequently sprayed with Surface Treatment Bath 1 (c~ " I,uosiLiu, ~
given below) heated to 60 C. The spray treatment consisted of 3 sprays of 5
seconds each separated by 5 second intervals for a total of 25 seconds. This
was followed in order by rinsing with tap water, spraying for 10 seconds with de-
ionized water (with a resistivity of at least 3,000,000 ohm-cm), and drying in a hot-air drying oven at 180 C for 2 minutes.
Surface Treatment Bath 1
75 % Aqueous ~,l lOa~l ,oric acid (H3P04): 10.0 g/L (Po4'3 ions: 7.2 g/L)
Sodium pylu,.,l-r,~pl~ ' (Na4P20,-10H20): 3.0 g/L (P20, ions: 1.2 g/L)
Water-Soluble Polymer 1: 2.0 glL (solids)
26 pH: 4.0 (adjusted with sodium hydroxide)
Balance: water
For Water-Soluble Polymer 1, n = 5, X' and x2 = hydrogen, Z = -CH2N(CH3)2 in
formula (I), and the average Yalue for Z moiety s~ Ihstitl Ition = 0.25.
~xample 2
The Dl aluminum cans were cleaned according to the procedure de-
scribed in r-xample 1 and then immersed for 20 seconds in Surface Treatment
Bath 2 (w" ,~ given below) heated to 60 C. This treatment was followed
13
W0 95128509 2 1 8 7 7 q 5
by rinsing with water and drying according to the procedure described in Examp-
le 1 .
Surface Treatment Bath 2
75 % Aqueous ~ u:~,ul ,u, i,, acid (H3PO4): 10.0 g/L (PO4J ions: 7.2 g/L)
6sodium p~lupll~a~.lldl~ (Na~P20r10H20): 3.0 g/L (P207~ ions: 1.2 g/L)
Water-Soluble Polymer 1: 0.4g/L (solids)
pH: 3.0 (adjusted with sodium carbonate)
Balance: water
Water-Soluble Polymer 1 was the same as described in Example 1.
.0 FY~mple 3
The Dl aluminum cans were cleaned according to the procedure de-
scribed in Example 1 and then immersed for 60 seconds in Surface Treatment
Bath 3 (~" ,~ . .., given below) heated to 35 C. This treatment was followed
by rinsing with water and drying according to the procedure described in Examp-
16 le 1.
Surface Treatment Bath 3
75 % Aqueous ~I)GSPI ~U~;~, acid (H3PO4): 20.0 g/L (PO4-3 ions: 14.4 g/L)
Sodium p~" u~ JI ,dle (Na4P2O7 10 H2O): 6.0 g/L (P2O7~ ions: 2.4 g/L)
Water-Soluble Polymer 1: 8.0 g/L (solids)
20 pH: 6.0 (adjusted with sodium hydroxide)
Balance: water
Water-Soluble Polymer 1 was the same as described in Example 1.
FY~rnDle 4
The Dl aluminum cans were cleaned according to the procedure described in
26 Example 1 and then sprayed with Surface Treatment Bath 4 (~" ,~osi~iu,~ givenbelow) heated to 65 C. The spray treatment consisted of 3 sprays (6 seconds
each) separated by intervals of 2 seconds (total of 22 seconds). This treatment
was followed by rinsing with water and drying according to the procedure de-
scribed in Example 1.
30 Surface Treatment Bath 4
75 % Aqueous ~l lu~JI ,u, i~, acid (H3PO4): 1.5 g/L (PO4 3 ions: 1.1 g/L)
14
21 i'~l7~
WO 951Z8509 r~
Sodium p~rlv,ul lu:,,ul Idle (Na4P2O7 1 ûH2O): 5.0 g/L (P2O7-4 ions: 2.0 g/L)
Water-Soluble Polymer 1: 4.0 g/L (solids)
pH: 2.5 (adjusted with nitric acid)
Balance: water
s Water-Soluble Polymer 1 was the same as described in Example 1.
Fx~mple 5
The Dl aluminum cdns were cleaned according to the procedure de-
scribed in Example 1 and then immersed for 30 seconds in Surface Treatment
Bath 5 (w,,,,uv~i~iu,, given below) heated to 60 C. This treatment was followedby rinsing with water and drying according to the procedure described in Examp-
le 1 .
SurFace Treatment Bath 5
75 % Aqueous pl~os~l~u, i~ acid (H3PO4): 30.0 g/L (Poi3 ions: 21.6 g/L)
Sodium tripoly,ul lo:"ul, (NasP3O~0): 1.2 g/L (P3O~o-s ions: 0.8 g/L)
Water-Soluble Polymer 1: 2.0 g/L (solids)
pH: 3.5 (adjusted with sodium hydroxide)
Balance: water
Water-Soluble Polymer 1 was the same as described in Example 1.
FY~mDle 6
The Dl aluminum cans were cleaned according to the procedure de-
scribed in Example 1 and then sprayed with Surface Treatment Bath 6 (composi-
tion given below) heated to 60 C. The spray treatment consisted of 2 sprays of
5 seconds each separated by an interval rJF 5 seconds for a total of 15 seconds).
This treatment was followed by rinsing with water and drying according to the
procedure described in Example 1.
Surface Treatment Bath 6
75 % Aqueous fJI lu~,ul~O~ ic acid (H3PO4): 10.0 s/L (PO4~3 ions: 7.2 g/L)
Sodium p~lu~l lOapl Idll~ (Na4P2O7-1 OH2O): 3.0 g/L (P2O7 4 ions: 1.2 g/L)
Water-Soluble Polymer 2: 2.0 g/L (solids)
pH: 5.0 (adjusted with sûdium hydroxide)
Balance: water
21 87795
WO 9~/28509 P~
For Water-Soluble Polymer 2, in formula (I), n = 5, X1 and x2 = -C2Hs, and Z =
-CH2N(CH2CH20H)2, and the average value for Z moiety c~ IhCtitl Itilll = 1 0.
FY~rnDIe 7
The Dl aluminum cans were cleaned according to the procedure de-
5 scribed in Example 1 and then immersed for 30 seconds in Surface TreatmentBath 7 (cu,,,, ' , given below) heated to 60 C. This treatment was followed
by rinsing with water and drying according to the procedure described in Examp-
19 1 .
Surface Treatment Bath 7
.0 75 % Aqueous pl)ospl IUI iC acid (H3P04): 10.0 g/L (P04 3 ions: 7.2 g/L)
Sodium p~lupl)~,ulldl~ (Na4P207-1ûH20) 3.0 g/L (P207-4 ions: 1.2 g/L)
Water-Soluble Polymer 3: 2.0 g/L (solids)
pH: 4.0 (adjusted with sodium hydroxide)
Balance: water
For Water-Soluble Polymer 3, in formula (I), n = 2, X~ and x2 = -C2Hs, and Z =
-CH2N(CH2CH2CH20H)2, and the average value for Z moiety s~ tion = 0.6.
ComDarative FY~mple 1
The Dl aluminum cans were cleaned according to the procedure de-
scribed in Example 1 and then sprayed with Surface Treatment Bath 8
20 (-,UlllUOait;VI) given belrw) heated to 60 C. The spray treatment consisted of 5
sprays of 4 seconds each separated by intervals of 5 seconds each, for a total
of 40 seconds. This treatment was followed by rinsing with water and drying ac-
cording to the procedure described in Example 1.
Surface Treatment Bath 8
2s 75 % Aqueous ,uI)o~ul ,oric acid (H3PO4): 10.0 g/L (PO4~3 ions: 7.2 g/L)
Water-Soluble Polymer 1: 2.0 g/L (solids)
pH: 3.0 (adjusted with sodium carbonate)
Balance: water
Water-Soluble Polymer 1 was the same as described in Example 1.
Comr~arative ExamDle 2
The Dl aluminum cans were cleaned accordinJ to the procedure de-
16
~W0 95/28509 2 ~ 8 7 7 9 5
scribed in Exampie 1 and then immersed for 30 seconds in Surface Treatment8ath 9 (w,,, " , given below) heated to 60 C. This treatment was followed
by rinsing with water and drying acwrding to the procedure described in Examp-
le 1 .
sSurface Treatment Bath 9
75 % Aqueous pl~CJa~Ul IUI i~, acid (H3PO4): 1 .û g/L (Poi3 ions: 0.72 g/L)Water-Soluble Polymer 1: 2.0 g/L (solids)
pH: 7.0 (adjusted with sodium hydroxide)
Balance: water
.0 Water-Soluble Polymer 1 was the same as described in Example 1.
ComDarative Example 3
The Dl aluminum cans were cleaned according to the procedure described in
Example 1 and then immersed for 5 sewnds in Surface Treatment Bath 10
(Wl I Ir "' I given below) heated to 60 C. This treatment was followed by rins-ing with water and drying according to the procedure described in Example 1.
SurFace Treatment Bath 1û
75 % Aqueous ,ul loa,ul IUI iC acid (H3P04): 10.0 g/L (P04~3 ions: 7.2 g/L)
Sodiump~"u~ Oa~ulId~ (Na4P2O71OH2O): 1.0g/L (P2O7-4ions: 0.4glL)
Water-Soluble Po~ymer 1: 0.05 g/L (soiids)
pH: 4.0 (adjusted with sodium carbonate)
Balance: water
Water-Soluble Polymer 1 was the same as described in Example 1.
CCl~ dl~';ic ExamDle 4
The Dl aluminum cans were cleaned according to the procedure de-
25 scribed in Example 1 and then immersed for 20 seconds in Surface Treatment
Bath 11 (c~ ~ "~,o~ given below) heated to 60 C. This treatment was followed
by rinsing with water and drying acwrding to the procedure described in Examp-
le 1 .
Surface Treatment Bath 11
95 % Aqueous sulfuric acid (H2SO4): 2.0 g/L (SOi2 ions: 1.9 g/L)
Sodium p~lu,ul lu5,ul 1 ' (Na4p2o7~ 1 OH20): 1.0 g/L (P2O7 ion: 0.4 g/L)
17
2 1 87795
WO 95/28509 r~ q~
Water-Soluble Polymer 1: 0.05 g/L (solids)
pH: 3.5 (adjusted with sodium carbonate)
Water-Soluble Polymer 1 was the same as described in Example 1.
C~ tu~ EY~tole 5
The Dl aluminum cans were cleaned according to the procedure de-
scribed in Example 1 and then immersed for 30 seconds in Surface Treatment
B~th 12 (~, Iluuai~iul, given below) heated to 60 C. This treatment was followed
by rinsing with water and drying according to the procedure described in Examp-
le 1 .
~2 Surface Treatment Bath 12
75 % Aqueous ~JI lu~,ul ,u, i. acid (H3PO4): 1 .û s/L (Poi3 ions: 0.72 g/L)
Sodium pyl ulJI lOalJl Idlt: (Na4P2O7 10 H2O): 1.0 g/L (P2O;4 ions: 0.4 g/L)
Water-Soluble Polymer 4: 2.0 g/L (solids)
pH: 4.0 (adjusted with sodium hydroxide)
~6 Balance: water
For Water-Soluble Polymer 4 in formula (I) n = 5 x1 and x2 = -C2Hs and Z =
-CH2SO3H and the average value for -CH2SO3H c~ ~ Itit n = 0.6.
Comparative Examole 6
The Dl aluminum cans were cleaned according to the procedure de-
22 scribed in Example 1 and then immersed for 30 seconds in Surface Treatment
Bath 13 (cu".r , given below) heated to 60 C. This treatment was followed
by rinsing with water and drying according to the procedure described in Examp-
le 1 .
Surface Treatment Bath 13 (surface treatment bath_described in Japanese
Patent Application Laid Open [Kokai or U"~d",i"ed] Number Hei 4-66671 )
75 % Aqueous ~ a,ul~oric acid (H3PO4): 1.0 g/L (Poi3 ions: 0.72 g/L)
Sodiump~"u,ul,~ul, (Na4P207-10H20): 1.0g/L (P20j4ions: 0.4g/L)
Water-Soluble Polymer 5: 2.0 g/L (solids)
pH: 4.0 (adjusted with sodium hydroxide)
32 Balance: water
Water-Soluble Polymer 5 had the following formula (IV):
18
~woss/28sos 2 1 87795 p~""~
CH --CH 2
~LCH z N(CH 2 CH 2 CH 2 OH) 2 ( IV )
S OH _ n
n=20
Cc" I IUdl ~ C Fy~rnr~le 7
,0 The Dl aluminum cans were cleaned according to the procedure de-
scribed in Example 1 and then immersed for 3û seconds in Surface Treatment
Bath 14 (culllr " , given below) heated to 60 C. This treatment was followed
by rinsing with water and dryins according to the procedure described in Examp-
le 1 .
s Surface Treatment Bath 14
75 % Aqueous ul lu:,~JI ,ù~i,, acid (H3PO4): 1.0 g/L (Poi3 ions: 0.72 glL)
Sodium p~, uul luaul Idle (Na4P2O7 10 H2O): 1.0 glL (P2O7 4 ions: 0.4 glL)
Water-Soluble Polymer 6: 2.0 g/L (solids)
pH: 4.0 (adjusted with sodium hydroxide)
Balance: water
Water-Soluble Polymer 6 had the following formula (V) (resin described in
Japanese Patent Application Laid Open [Kokai or Ul,c,,~d,,,i,,ed] Number Hei
2-608):
OH
~CH 2 (V)
~CH 2 N(CH 2CH 2CH 2OH) 2
n=10
C~s~IIUdl..~C Example 8
The Dl aluminum cans were cleaned according to the procedure de-
19
2 ~ 8779~
W0 95128509
DINE¢D 404 non-chromate surface treatment agent, manufactured by Nihon Par-
kerizing Company, Limited, heated to 40 C. This spray treatment consisted of
3 sprays of 5 seconds each separated by 5 second intervals for a total of 25 sec-
onds. This treatment was followed by rinsing with v,~ater and drying according to
5 the procedure described in Example 1.
The evaluation results for Examples 1 to 7 and Cu" IIJdl ~ lc Examples 1
to 8 are reported in Table 1.
TAhl~ 1. Results of the EVAII lAt;rlrlS
E~ample or Compar- r~ ' O Peel StrenOth, Coefficient of
isoll E~ample ~umber Resistance kOf/5mm Static F~iction
Example I + 4.0 0.9
Example 2 + 4.0 0.9
15Example 3 + 4 0 0.9
Example 4 + 4 0 0.9
Example 5 + 4.0 0.9
Example 6 + 4 0 0.9
Example 7 + 4.0 0.9
2~Comparative Example I x 2.0 1.3
C~ Example 2 x x l.S 1.5
C.~ , Example 3 x x 2.0 I.S
C . v~, Example 4 x x 1.5 1.5
Comparative Example S x x l.S 1.6
25Comparative Example 6 + 2.0 1. I
C. . v~, Example 7 x x 1.5 1.6
Cl . ~ Example 8 + 4.0 1.6
As the results in Table 1 make clear, Examples 1 to 7, which used surface
30 treatment w" Ir "' I:~ and surface treatment methods according to the present
invention, yielded surface-treated metals with an excellent Lld-~h~l lil l9 resistance,
excellent ddl It~ and excellent slideability. In contrast to this, Sdli ~rd~lUI y
~W0 951~8S09 2 ~ 9 5
vaiues could not be simultaneously obtained for all these properties (conrosion
resistance, paint adl lel el ~ce, and t " ' ' "~.~;) in the case of the surface-treated
metals afforded by surface treatment baths outside the scope of the present in-
vention (Cu~ Jdl~ C Examples 1 to 8).
6 Benefits of the Invention
As the preceding de:~u i~Aiu,, has made clear, the surface treatment com-
position and surface treatment method according to the present invention can
produce very corrosion-resistant and hi3hly paint-adherent c~ " coatings
on the surface of aluminiferous metais prior to the painting thereof. In particular,
,, ' " , of the surface treatment ~, . IL " , according to the present inven-
tion to the treatment of Dl aluminLm ct~ns results in the formation on the surface
of Dl aluminum cans prior to its paintina ~r printing of a very corrosion-resistant
and highly paint-adherent film that also provides the excellent slideability required
for smooth conveyor transport of the c~n. Since the surface treatment compo-
s sition according to the present invention and the surface treatment bath used inthe invention method do not contain chromium or fluorine, they have the excel-
lent adva"~a~e of reducing the load on waste water treatment.
