CA1180644A - Compositions and methods for the acid cleaning of aluminum surfaces - Google Patents

Abstract

Abstract of the Disclosure Compositions and methods for cleaning aluminum surfaces wherein the cleaning compositions contain sulfuric acid, hydrofluoric acid, and an alkali metal 2-butoxyethoxyacetate.

Description

The invention relates to a COJnpOSitiOn and method for cleaning aluminum surfaces wherein the cleaning compositions contain sulfuric acid, hydrofluoric acid, and an alkali metal 2-butoxyethoxyacetateO
In the manufacture of containers composed of al-~inum and aluminum alloys, a drawing and Eorming operation is employed (collullonly referred to as drawing and ironing). This operation results in the deposition of lubricants and forming oils on the surfaces of the aluminum containers. In adclitioll, residual aluminum fines, i.e~ small particles of alumillum, are cleposited Oll both the interior and e.~terior surfaces. Orclinarily, the exterior surface of the container will have smaller quantities of aluminum fines than the interior surface since during the drawing and ironing step the e~terior surface is not subjected to as much abrasion from -the die as the interior surface.
Prior to any processing steps, such as conversion coating and sanitary lacquer deposition, the surfaces of the aluminum containers must be clean and water-break-free, i.eO free of contaminants that interfere with further processing and render the containers macceptable for useO
Compositions and methods for the low temperature cleaning of aluminum surfaces are disclosed in United States Patent No. 4,009,115 issued February 22, 1977 to Robert Eric Binns, United States Patent NoO 4,116,853 issued September 26~ 1978 to Robert Eric Binns, ~lited States Patent NoO 4,124,407 issued November 7, 1978 to Robert Eric Binns, and United States Patent No~
3,969,135 issued July 13, 1976 to Peter F. King, et al. These patents disclose cleaning compositions containing sulfuric acid, hydrofluoric acid or a fluoride salt, and a surfactantO
Compositions falling within the disclosures of these patents are commercially successful and are in fact used e~tensively in the cleaning of b~

aluminum and aluminum alloy containers. Such commercial compositions typically utilize a combination oE two nonionic surfactants to enhance the cleaning perfor3nance and minimize foamingO
One of the problems in utilizing the prior art acid cleaning compositions is caused by the build-up of lubricants and forming oils used in the drawing and forming of aluminum containers as these containers are treated with the cleaning solutionsO The cleaning solutions must bc replenis}led wit]
fresh solutions from time to time to keep the oil level down. l~llen the oil levels become excessive in the cleaning bath, containers cleaned in the bath exhibit significant water breaks after the cleaning solution is rinsed off.
Water breaks are an indication that ~he surface of the aluminum is not clean and that oils or other foreign deposits are present. Such cans must be discarded or recleaned since they are not suitable for further processing as containers for beverages and other comestiblesO
It has now been discovered that a particular anionic surfactant, i eO, an alkali metal 2-butoxyethoxyacetate~ when used alone or in combination with one or more low foaming nonionic surfactants in the sulfuric acid~hydrofluoric acid compositions of the prior art, has surprising advantages over known compositions containing the surfactants and surfactant combinations currently in use therein.
It has been found that the cleaning solutions of the present invention can tolerate relatively high concentrations of lubricants and forming oils without any water breaks occurring on the containers cleaned by such solutions.
~lence, significant economies are realiæed since large numbers of containers can be processed before the operation must be shut down in order to replenish all or part of the cleaning solution.

4 ~

Another significant advantage of the present cleaning compositions is the almost complete absence of foam in the cleaning bath and in tlle rinsing cycle following the cleaning step. Many of the acid cleaning compositions currently on the market exhibit problems with foam to a greater or lesser extent~ Such compositions are mixtures of a higll foaming nonionic surfactant to achieve good cleaning action with a low foaming anionic surfactc~lt to try to contain the quantity of Eoam that would otherwise result. ~oamillg often results :in overElow or dropping of the Eoam onto the Eloor of the facility containing the operation, resulting in slippcry and msafe conditions. Also, appearance of foam may lead to the operator's conclusion that the cleaning solution is not satisfactory due to the risks of foam overflow. Accordingly, the container cleaning operations must be shut down while the foam is skimmed off or the cleaning solution is replenished, leading to los~ time and decreased flow-through of containersO
A further advantage of the present cleaning compositions is that the alkali metal 2-butoxyethoxyacetate can be utilized effectively in relatively small quanti~ies, and this factor, combined with the already inexpensive cost of this surfactant (as the sodium salt) conlpared with the nonionic surfactants currently in use, results in great economic savings over the present con~ercial compositions. Significant cost savings are also realized even when a low foaming nonionic surfactant or a combi1latioll of such surfactants is also present in the cleaning composition of the invention, since the noniollic surfactant~s) is also present in relatively small quantities.
Typically, concentrates containing the sulfuric acid and the surfactant are prepared by the manufacturer and sold to container processing companies ~ho make up cleaning solutions by diluting such concentrates with ~ater and adding hydrofluoric acid -to the solutions. Concentrates currently on the market tend to be rather highly colored, due to decomposition products formed from the action of concentrated sulfuric acid on the surfactants and/or from interactions between the surfactants and impurities in the commercial sulfuric acid which is commol1ly used in formulating the concentrates. Surpris-ingly, concentrates formed with an alkali metal 2-buto~yetho~yacetate as the sole surfactant present are colorless or only slightly yellow in color. Sucll concentrates are stable at very low temperatures, e.g. no precipitation occurs even at the temperature of a dry ice-acetone bath. ~lso, the concentrates are stable and do not discolor even when subjected to temperatures at 50C for periods of three weeks or moreO ~lost concentrates currently in use discolor even at room temperature~ and precipitates form in some when containers of the concentrates are placed in dry ice-acetone baths. The great stability of the present compositions permits their shipment and storage under adverse temperature conditions without problems, a further significant economic advantage.
Another advantage of the presen-t inven~ion is the high level of cleanliness produced in the containers, particularly when a low foaming nonionic surfactant is also present, providing for unusually uniform conversion coating and lacquer deposition on the containers during their further processingv Interestingly, when the only anionic surfactant disclosed in Binns~
' ~ ~nited States Patents Nos. ~I,009,115; 4,116,853; and ~124,407, i.e. Tergitol Anionic 08 (sodi~ml 2-ethyl he~yl sulfate), was tested in the acid cleaning compositions of these patents, water breaks occurred on the alu1llinum containers cleaned with such compositions after the addition of only small quantities of forming oils~ ~1ence, the surprising advantages discovered with ~he anionic ~ frc~cl e ,~ `k 4 surfactant of the present inventio11 appear to be unique and clearly are not advantages common to anionic surfactants in general.
The yresent inven-tion relates -to aqueous cleaning compositions ancl pro-cesses for the cleculing of aluminum surfaces, and to concentrates used in form-ing the cleaning compos:i-tiol1s.
Il1e compositions alld processes of the inve11t;o11 coml)rise improveme11ts over -the compositions a1lcl processes disclosed allcl clnlmecl in Bin1ls' Ullitccl States Patent Nos. ~1,00~,115; ~1,ll~,S53; ;u1d ~,12~ 107. 'Ihc proce(lurcs and metllods used therein in carrying out the cleanillg operatiolls alld ill forming the concentrates and cleaning solutiolls are equally applicable to the present invel1-tion unless otherwise stated herein.
The aqueous cleaning compositiol1s of the inve11tion comprise from about 1 to about 10 grams/liter, preferably from about 3 to about 5 grams/liter of sulfuric acid; from about 0.005 to about 0.1 grams/liter, preferably from about 0.01 to about 0.03 grams/liter of hydrofluoric acid; and from about 0.1 to about 10 grams/liter, preferably from about 0.2 to about O.S grams/liter of ail alkali metal 2-butoxyethoxyacetate. Ihe alkali metal 2-butoxyetlloxyacetate is prefer-ably sodium 2-butoxyetl1oxyaceta-te [Cil3(C112)30C~12C1120Cil2C-0(3N.lOE)], sold commer-cially under the trademark "~IIr~ ET B" by the ;~liral1ol Cl1emical Comp~u1y, Inc. as an aqueous solution contai11il1g 41). 0O sodium 2-butoxyetlloxyacetatc . Otller alkali metal salts can equally well be eml-loyed, e.g. pOt;155iUIll 2-blltoxyetl1oxyacetate or lithiu1ll 2-butoxyet11oxyacet;lte. O}ltion;l11y, but l~refer<-LL ly, from about 0.1 to about 10 grallls/1iter, preferab1y from al)ollt o~ 2 to .LboUt o~ S grams/liter of one or a combinatio11 of t~o or more low t~oami11g nolliol1ic surfactal1ts is also presen-t.
~\dvantageously, a ~eight ratio of alliali ~n~

metal 2-butoxyethoxyacetate to nonionic surfactant ~f about 1:1 is used.
The term "low foaming nonionic surfactant" means that the nonionic surfactant or combination of nonionic surfactants give less than 20 ~n. of foam after five minutes standing in the well known Ross-Miles Fo~m Test at 50C.
Examples of such low foaming nonionic surEactants that can be used alone or in combination in the practice of the invention include the following:
TRITON* DF-16 ~Rohm ~l l-laas CoO) a nonionic surfactant believecl to be a modif:ied polyethoxylated straight chain alcohol;
POLYTERGENT* S-505 LF ~Olin Corp~ a nonionic suractant believed to be a modified polyethoxylated straight chain alcohol;
SURFONIC* LF-17 ~Jefferson Chem:ical CoO) a nonionic surfactant believed to be an alkyl polyethoxylated e~her;
ANTAROX* BL 330 ~GAF Corp.) a nonionic surfactant believed to be an alkyl poly ~ethyleneoxy) ethanol;
TRITON* CF-10 ~Rohm ~ Haas Co.) a nonionic surfactant, and believed to be an alkylaryl polyether having a carbon chain of about 14 carbon atoms and approximately 16 moles of ethoxylation;
PLURONIC* LO61 ~BASF Wyandotte, Inc.) a nonionic surfactant~ and believed to be a condensate containing only ethylene oxide and propylene oxide chains;
ANTAROX* LF-330 ~GAF Corp.) a nonionic surEactant, believed to be an alkyl poly(ethyleneoxy) ethanol;
hlIN-FOAhl* 1~ (Union Carbide Corp.) a nonionic surfactant believed to be aikyloxy~polyethyleneoxypropyleneoxyisopropanol) having a molecular weight of about 706.
*Trademark The pH of the above cleaning compositions of the invention is preferably maintained in the range of about loO to about 1.8 and most preferably in the range of about 102 to about 1.5~ although a pll of from about 0.6 to about 2.0 can be usedO
The concentrates o:E the present inventlon, which advantageously may be used in forming the cleaning solution of the invention, comprise from about 200 to about 600 grams/liter of sulfuric acid and from about 0.01 parts to about 10 partsJ and preferably from about 0~04 parts to about 0.27 parts b~ weight of alkaii metal 2-butoxyethoxyacetate per part of sulfuric acid in the concentrateO Using the above ratios for the alkali metal 2-butoxyethoxy-acetate as a guide, and depending on the quantity of sulfuric acid desired in the cleaning solution of the invention, the actual quantity of alkali metal

2-butoxyethoxyacetate in the concentrate is determined from within the above ratios so that the desired quantity of alkali metal 2-butoxyethoxyacetate is present in the cleaning solution when the concentrate is diluted with an appropriate quantity of waterO For example, if 1 gram/liter of sulfuric acid is desired in the cleaning solution9 then from about Ool grams to about 10 grams of alkali metal 2 butoxyethoxyacetate is present in the concentrate per gram of sulfuric acidO If 10 grams/liter of sulfuric acid is desired in the cleaning solution, then from about 0~1 grams to about 1 gram of alkali metal 2-butoxyethoxyacetate is present in the concentrate per gram of sulfuric acid~
QptiQnally, from about 0.01 parts to about 10 parts, preferabl~
from about 0O04 parts to about 0.27 parts by ~eigilt of one or a combination of lo~Y foaming nonionic surfactants is also present in the concentra-tes of the invention~
The above concentrate is thell added to water in controllled amounts ~ ~0~

sufficient to procluce a cleaning solution having the desired quantities of sulfuric acid and alkali metal 2-butoxyethoxyacetate. Hydrofluoric acid in quantities ~sufficien* to give the desired amount is usually added separately ~o the cleaning solut:ion. While the hydrofluoric acid can be added to the concentrate in quantities sufficient to produce the requisite amounts in the cleaning solution when the concentrate is added to water, it is much preferred to add the hydroEluoric acid separately to -the cleaning solution in careEully metered quantities on a contilluillg controlled basis. Separate monitored addition of hydrofluoric acid is preferred because the cleaning solution continually loses hydrofluoric acid as etching of the aluminum containers takes place during the cleaning stage.
The processes of the invention comprise contacting the al~ninum or aluminum alloy surfaces to be cleaned with the aqueous cleaning compositions of the invention using any of the contacting techniques known to the art, such as conventional spray or immersion methods. The temperature of the cleaning composition is preferably maintained in the range of from about 115F
to about 1~5F for maximum cleaning effect> although temperatures as low as 90F can be employedO Treatment times with the cleaning solu-tions are usually of the order of about lS seconds to about 2 minutes. DesirablyJ the hydro-fluoric acid content of the cleaning solution and the contact time witll thealuminum surfaces is adjusted to give an alumillum dissolution of from about 8 to about 25 milllgramsl preferably from about 9 to about 20 milligrams, per square foot of aluminum surface treated~
The following examples are illustrative of the invention and are not intended to limit ito Example 1 A liter of concentrate was prepared containing the followiTIg quantities o:E ingredients:
Rer liter }l2S04~66 Baum~ 46702 g ~256 ml) H20 -709.6 g ~711 ml) MIRA~YET* B - 8806 g ~ 80 ml~
The above c.oncentrate was clear and substantially colorlessO 60.0 ml o:E the above concentrate was addecl to 5D9~0 liters of water to form six liters of solution containing ~.67 grams/liter of H2S04~66 Baume) and 0.434 grams/liter of sodium 2-butoxyethoxyacetate ~00886 g/l of MIRA~YET ~). 2Q PPM
of hydrofluoric acid was added to form ~he cleaning solution, and the cleaning solution stirred to render it uniform in compositionO
Aluminum cans of 3004 alloy drawn into single piece containers were employed in this procedureO The cans ~Yere covered ~ith aluminum fines and dra~ing oilsO
The test specimens were treated as follows:
~a) Sprayed with the above cleaning solution maintained at 130F
for one minute, (b) Rinsed with water by immersion in cold water for 30 seconds, ~c) Allowed to stand for 30 seconds, after which they were examined for water breaks on botll the inslde and outside, and 2Q ~d) The inside wiped witll a clean wllite cloth and the cloth examined for aluminum fines.
A can ~as -testecl as above and the results noted Then S ml of a cooling oil emulsion ~Ised by Reynolcls Aluminum Company in the drawing and *Trademark forming of alumimlm cans was added to the cleaning solution and another can tested and the results noted. Another 5 ml of cooling oil was then added to the bath and another can was tested and the results noted. Additional 5 ml increments of cooling oil were added and a can tested after each addition until water breaks were obtained. Upon each acldition of cooling oll the amount of foam ln the bath was notedO
The results o:E these tests are glven in Table I bclow:
Table I
Addltlon o:E Coollng Extent o:E ~ater Alumlnum Fines Foam in Oil Emuls.ion Breaks on Cloth Bath .. . .. _ . .
O None None None 5 ml None None Very slight*

10 ml None None Very slight 15 ml None None Very slight 20 ml None None Very s-ight 25 ml None None Very slight 30 ml Slight None Very slight *no greater than 1/4" of foamO

Exam~le 2 10 Six liters of cleaning solution ~ere prepared by adding to water 28.02 grams of ll2SO4(66 Baume) 1.30 grams of sodi-~n 2-butoxyet}loxyacetate and 20 PPM of hydrofluoric acidO This cleanlng solutlon contalns 4.67 grams/

liter of ~l2SO4(66 Baume) ancl 00217 grams/liter of sodiulll 2-butoxyethoxyacetate (iOe~ one-half the amount present in the cleaning solution of Ex~nple l~o Aluminum cans from the same batch as were used in Example 1 were tested according to the conditions and procedures set forth in Example 1 with -lQ-the following results:
Table II
__ _ Addition of Cooling Extent of Water Aluminum Fines Foam in Oil Emulsion Breaks Oll Cloth ~ath 0 None None None 5 ml None None Very slight*
10 ml None None Very slight 15 ml None None Very slight 20 ml None None Very sligllt 25 ml None None Very slight 30 ml Slight None Very slight *no greater than 1/4" of foam.
Example 3 Six liters of an aqueous cleaning solution were prepared containing the following quantities of ingredients per liter:

H2SO4~66 Baume) _ 4~67 g Sodium 2-ethyl hexyl sulfate - 0O464 g ~0.98 ml of TERGITOL ~NIONIC** 08) ~ - 20 PPM
Aluminum cans from the same batch as those used in Example l were tested according to the conditions and procedures set forth in Example l with the following results:
Table III
Addition of Cooling Extent of lYater Aluminun) Fines Foam in Oil Emulsion Breaks on Cloth Bath _ . . ... . ..
0 Slight None None 5 ml Extensive* None None 10 ml Extensive None None *commercially unacceptable **Trademark ~11-) 6 ~ ~

Example 4 Six liters of an aqueous cleaning solution were prepared containing the quantities of ingredients set forth in Example 3 except that 0.928 g/l of sodium 2-ethyl hexyl sulfate was used. Test procedures were carried out as in Example 3 ~ith the following results:
Table IV

Addition of Cooling Exteni of Water Aluminum Fines Foam in Oil Emulsion Breaks on Cloth Bath 0 Slight None None 5 ml Extensive* None None 10 ml ~xtensive None None *commercially unacceptableO
Example 5 Six liters of an aqueous cleaning composition was prepared containing the following quantities of ingredients per liter:

H2SO4~66 Baume) - 4.70 g Ethoxylated abietic acid ~Hercules Surfactant AR 150)* - 10053 g Alkyl poly~ethyleneoxy)-ethanol ~ANTAROX*** LF-330)* - 00673 g *both nonionic surfactants~
Aluminum cans from the same batch as those used in Example 1 ~ere treated according to the procedure and conditions set :Eorth in Example 1 with the following results:

***Trademark Table V

Addition of Cooling Extent of Water Aluminum Fines Foam in Oil Emulsion Break on Cloth Bath O None Trace Slight**
5 ml Slight Trace Slight lO ml Extensive* Trace Slight *commercially unacceptable **between l/4" and 1".

Six liters o~ an aqueous cleaning solution l~ere prepared containing the following quantities of ingredients per liter:

H2S04~66 Baume) - 4.67 grams Modified polyethox~lated - 0.464 g.
straight chain alcohol (TRITON*** DF-16) ~nonionic surfactant) Aluminum cans from the same batch as those used in Example l ~ere treated according to the same procedures and conditions set forth in Example l with the following resultsO
Table VI

Addition of Cooling Extent of ~ater Aluminum Fines Foam in Oil Emulsion Breaks on Cloth Bath O None Trace Slight*
5 ml None Trace Slight 10 ml None Trace Slight 15 ~1 None Trace Slight 20 ml None Trace Slight 25 ml Slight Trace Slight *between l/4" and l~o ***Trademark -13-~:~8()6~

~ }___7 The follo~ing concentrates were prepared:
A per liter H2S04~66 Baume) ~467.2 g H20 _709.6 g Soclium 2-butoxyethoxy-acetate - 43~4 g B
H2S04~66 Baume) _ 467.2 g ~12 - 709.6 g Sodium 2-ethyl hexyl sulfate - 46.4 g ___ H2S04~66 Baume) _4G9.6 g H20 -62700 g Ethoxylated abietic acid ~Hercules Surfactant AR 150) - 105.3 g Alkyl pol~ (eth~leneoxy) ethanol (ANTAROX** LF-330) _ 6703 g H2S0~66 Baumb) -467.2 g H20 -709.6 g Modified polyethox~-lated straight chain alcohol ~TRITON** DF-16) ~ 4604 g Samples of the above concentrates were treated accordlng to the conditions sho~Yn and ~ith the results set forth in Table VII belo~:

**Trademark -14-

3 ~ 4 Table VII
_ 55C for Concentrate Dry Ice!Acetone Bath 0C or 24 hours 24 hours _ _ _. ._ . . _ _ _ . . . _ . _ . . ._: __. __A _.__ _ . _ _ _ _A.___ . _ A Sl, viscous clear, Clear, substan- Clear, sub-substantially colorl- tially colorless stantially ess solution solution colorless solution B* - _ C SigniEicant preci- Signiicant precl- Very dark pitate pita-te brown ~lis-coloration, some separa-tiOII i~lto layers D Slo viscous~ lightly Lightly colored hloderately colored brown solu- bro~yn solution colored -tion bro~yn solu-tion *Homogeneous solution could not be obtainedO TERGITOL** 08 layered on top of the sulfuric acid solutionO
Concentrate A was then placed in cm oven maintained at 50C for a period of three weeksO When the solution ~as removed~ it was clear and substantially colorless, i.e. no change in color occurred during this period.
Example 8 Six liters of an aqueous cleaning solution was prepared containing the follo~ing quantities of ingredients per liter:
H2SO~66 Baume) - 4O7 g MIRAlYET* B _ 0.3 g Aluminum cans of 3004 allo~ dra~yn into single piece containers were employed in this procedure. The cans ~yere covered with al-lminum fines and drat~ing oils.
*Trademark **Trademark

4'~

The test specimens ~ere treated as follows:
(a) Sprayed t~ith the above cleaning solution maintained at 125F, ~ b) Rinsed with ~ater by immersion in cold water for 30 seconds, and ~ c) Allowed ~o stand :Eor 30 seconds, after which they ~ere examined for ~ater breaks on both the inside and outsideO
A can was tested as above with a spray ti.me in step Ca) of 30 seconds, and the results noted. A second can was tested as above with a spray time in step ~a) of 45 seconds and the results notedO Then 200 PPM of NALCO*
XL 174, a mineral oil based coolant and lubricant for drawing, and ironing aluminum cans was added to the cleaning solution, and a third can was tested as above with a spray time in step ~a) of 30 seconds, and a fourth can with a spray time in step (a) of 45 seconds.
The results of these tests are given in Table VIII below:
Table VIII

Addition of Spray Time Extent of NALCO XL 174, PPM in Secondslrater Breaks ~ .
O 30 None 0 45 None 200 30 None 200 45 None E~ample 9 Si~ liters of cleaning solution ~Yere prepared by adding to water 4.7 g/1 of ~12SO4~66 Ba~le), 10053 g/l of Hercules Surfactant AR-150, 00673 gjl of SURFONIC* LF 17~ and 20 PPM of hydrofluoric acidO
Aluminum cans from the same batch as were used in E~ample 8 were tested according to the conditions and procedures set forth in E~ample 8 with *Trademark the following results:
Table IX
Addit.ion of Spray Time Extent o-f NALC0* XL 174~ PPM in Seconds Water Breaks ~ . . .
0 30 None 0 45 None 200 30 Extensive 200 ~5 Slig}lt Example 10 Six liters of an aqueous cleaning solution heavily cont~ninatecl ~ith NALC0 XL 174 was prepared containing the following ~uantities of ingredients per liter:
H2S04~66 Baume) - 4O7 g MIRAWET* B - 0 9 g NALCG* XL 174 - 500 PPM

Aluminum cans of 3004 alloy dra~Yn into single piece containers were employed in this procedure. The cans were covered with aluminum fines and drawing oilsO
The test specimens were treated as follows:
~a) Washed with tap water at 125~ for 30 seconds, ~b) Sprayed with the above cleaning solution maintained at 125 F
for 40 seconds, ~c~ Rinsed by spraying witll ~ap water for 20 seconds, ~d) Rinsed by spraying ~Yith cleionized water, and ~e) Allo~Yed to stand for 30 seconds, after which ~hey were examined *Trademark for ~ater breaks on both the inside and outside.
A can was tested as above and the results noted, Then to a portion of the above contaminated cleaning solution was added 0.9 g/l of a low foaming nonionic surfactant, and another can tested as aboveO This procedure was repeated with the addition of 0.9 g/l of different 10w foamillg nonionic surfactants to fresh portions of the above contaminated cleaning solution.
The results obtainecl are given ln Table X bclow:
Y`able X

Additloll of 0~9 g/l of Extent of nonionic surfactant_ _ Water Breaks None Extensive PLURAFAC* RA 30 Slight TRITON* DF 16 None SURFONIC* LF 7 None SURFONIC* LF 17 None ANTAROX* LF 330 Moderate As can be seen in this example~ even when a very heavy contaminant of a commercially used coolant is present in the compositions of the invention, the presence of a small quantity of a low foc~ming nonionic surfactant in addition to the alkali metal 2-butoxyethoxyacetate significantly increases the cleaning ability of the composition~

*Trademark -lS-~

Claims (23)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An aqueous cleaning composition for removing and dissolving aluminum fines and cleaning lubricating oils from aluminum surfaces comprising from about 1 to about 10 grams/liter of sulfuric acid, from about 0.005 to about 0.1 grams/liter of hydrofluoric acid, and from about 0.1 to about 10 grams/liter of alkali metal 2-butoxyethoxyacetate.

2. The composition of Claim 1 wherein the alkali metal 2-butoxyethoxy-acetate is sodium 2-butoxyethoxyacetate, and is present in amount from about 0.2 to about 0.8 grams/liter of cleaning composition.

3. The composition of Claim 1 wherein the pH is from about 1.0 to about 1.8.

4. The aqueous cleaning composition of Claim 2 wherein the sulfuric acid is present in amount of from about 3 to about 5 grams/liter, and the hydrofluoric acid is present in amount of from about 0.01 to about 0.03 grams/liter.

5. The aqueous cleaning composition of Claims 1, 2 or 3, wherein the hydrofluoric acid is present in an amount such that the composition has an aluminum dissolution rate of from about 8 to about 25 milligrams per square foot of aluminum surface treated at a temperature of 130°F and a contact time of one minute.

6. The aqueous cleaning composition of Claim 4, wherein the hydrofluoric acid is present in an amount such that the composition has an aluminum dissolu-tion rate of from about 8 to about 25 milligrams per square foot of aluminum surface treated at a temperature of 130°F and a contact time of one minute.

7. An aqueous cleaning composition in accordance with claim 1, 2 or 3, wherein from about 0.1 to about 10 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in the composition.

8. An aqueous cleaning composition in accordance with claim 4, wherein from about 0.1 to about 10 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in the composition.

9. An aqueous cleaning composition in accordance with claim 1, 2 or 3, wherein from about 0.2 to about 0.8 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in the composition.

10. An aqueous cleaning composition in accordance with claim 4, wherein from about 0.2 to about 0.8 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in the composition.

11. A process for cleaning an aluminum surface comprising the steps of (a) contacting said surface with an aqueous cleaning solution comprising from about 1 to about 10 grams/liter of sulfuric acid, from about 0.005 to about 0.1 grams/
liter of hydrofluoric acid, and from about 0.1 to about 10 grams/liter of alkali metal 2-butoxyethoxyacetate, and (b) rinsing the aluminum surface to remove the cleaning solution.

12. The process of claim 11, wherein the alkali metal 2-butoxyethoxyacetate is sodium 2-butoxyethoxyacetate and is present in amount of from about 0.2 to about 0.8 grams/liter of cleaning solution.

13. The process of claim 11, wherein the aqueous cleaning solution is con-tacted with an aluminum surface by spraying said solution onto the surface.

14. The process of claim 11, wherein the solution temperature is maintained in the range of from about 115°F to about 145°F.

15. The process of claim 11, wherein said cleaning solution comprises from about 3 to about 5 grams/liter of sulfuric acid, from about 0.01 to about 0.03 grams/liter of hydrofluoric acid, and from about 0.2 to about 0.8 grams/liter of sodium 2-butoxyethoxyacetate.

16. The process of claim 11, 12 or 13, wherein from about 0.1 to about 10 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution.

17. The process of claim 14 or 15, wherein from about 0.1 to about 10 grams/
liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution.

18. The process of claim 11, 12 or 13, wherein from about 0.2 to about 0.8 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution.

19. The process of claim 14 or 15, wherein from about 0.2 to about 0.8 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution.

20. The process of claim 11, 12 or 13, wherein from about 0.1 to about 10 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution, wherein the aluminum surface is an aluminum can.

21. The process of claim 14 or 15, wherein from about 0.1 to about 10 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution, wherein the aluminum surface is an aluminum can.

22. The process of claim 11, 12 or 13, wherein from about 0.2 to about 0.8 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution, wherein the aluminum surface is an aluminum can.

23. The process of claim 14 or 15, wherein from about 0.2 to about 0.8 grams/liter of one or a mixture of at least two low foaming nonionic surfactants is also present in said aqueous cleaning solution, wherein the aluminum surface is an aluminum can.