CLEANING AND SURFACE CONDITIONING OF FORMED METAL CLEANING AND SURFACE CONDITIONING OF FORMED METAL SURFACES SURFACES

WO 96/19553 PCT/US95/16014 CLEANING AND SURFACE CONDITIONING OF FORMED METAL SURFACES CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Serial No. 126,143 filed September 23,1993, which was a continuation of Application Serial No. 910,483 filed July 8,1992 and now abandoned, which was a continu- s ation-in-part of copending application Serial No. 785,635 filed October 31,1991 and now abandoned, which was a continuation of application Serial No. 521,219 filed May 8,1990, now U.S. Patent No. 5,080,814, which was a continuation of application Serial No. 395,620 filed August 18,1989, now U.S. Patent No. 4,944, io 1987, now U.S. Patent No. 4,859,351. The entire disclosures of all the afore¬ mentioned patents, to the extent not inconsistent with any explicit statement herein, are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention is This invention relates to a cleaner and surface conditioner for formed met¬ al surfaces, and particularly, to such a lubricant and surface conditioner which improves the mobility of aluminum cans without adversely affecting the adhesion of paints or lacquers applied thereto, and also enables lowering the dryoff oven temperature required for drying said surfaces. Still more particularly, this inven- WO 96/19553 PCMJS95/16014 tion relates to a combination of cleaning and such surface conditioning which minimizes the formation of sludge or other undesirable phase separation during the process of surface conditioning when the surface conditioner contains metallic elements as part of its chemical composition.

s Discussion of Related Art Aluminum cans are commonly used as containers for a wide variety of products. After their manufacture, the aluminum cans are typically washed with acidic cleaners to remove aluminum fines and other contaminants therefrom.

Recently, environmental considerations and the possibility that residues remain- io ing on the cans following acidic cleaning could influence the flavor of beverages packaged in the cans has led to an interest in alkaline cleaning to remove such fines and contaminants. However, the treatment of aluminum cans generally re¬ sults in differential rates of metal surface etch on the outside versus on the inside of the cans. For example, optimum conditions required to attain an aluminum is fines-free surface on the inside of the cans usually leads to can mobility problems on conveyors because of the increased roughness on the outside can surface.

These aluminum can mobility problems are particularly apparent when it is attempted to convey the cans through single filers and to printers. Thus, a need has arisen in the aluminum can manufacturing industry to modify the coeffi- cient of static friction on the outside and inside surfaces of the cans to improve their mobility without adversely affecting the adhesion of paints or lacquers ap¬ plied thereto. The reason for improving the mobility of aluminum cans is the gen¬ eral trend in this manufacturing industry to increase production without additional capital investments in building new plants. The increased production demand is requiring can manufacturers to increase their line and printer speeds to produce more cans per unit of time. For example, the maximum speed at which alumin¬ um cans, in the absence of any treatment to reduce their coefficient of surface friction, may be passed through a printing station typically is on the average of about 1150 cans per minute, whereas it is desired that such rate be increased so to about 1800 to 2000 cans per minute or even higher.

However, aluminum cans thoroughly cleaned by either acid or alkaline cleaners are, in general, characterized by high surface roughness and thus have WO 96/19553 PCT/US95/16014 a high coefficient of static friction. This property hinders the flow of cans through single filers and printers when attempting to increase their line speed. As a re¬ sult, printer misfeeding problems, frequent jammings, down time, and loss of pro¬ duction occur in addition to high rates of can spoilage, s Another consideration in modifying the surface properties of aluminum cans is the concern that such modification may interfere with or adversely affect the ability of the can to be printed when passed to a printing or labeling station.

For example, after cleaning the cans, labels may be printed on their outside sur¬ face, and lacquers may be sprayed on their inside surface. In such a case, the io adhesion of the paints and lacquers is of major concern.

In addition, the current trend in the can manufacturing industry is directed toward using thinner gauges of aluminum metal stock. The down-gauging of aluminum can metal stock has caused a production problem in that, after wash¬ ing, the cans require a lower drying oven temperature in order to pass the col¬ is umn strength pressure quality control test. However, lowering the drying oven temperature resulted in the cans not being dry enough when they reached the printing station, and caused label ink smears and a higher rate of can rejects.

Thus, it would be desirable to provide a means of improving the mobility of aluminum cans through single filers and printers to increase production, re- duce line jammings, minimize down time, reduce can spoilage, improve ink lay- down, and enable lowering the drying oven temperature of washed cans. Ac¬ cordingly, it is an object of this invention to provide such means of improving the mobility of aluminum cans and to overcome the afore-noted problems.

In the most widely used current commercial practice, at least for large as scale operations, aluminum cans are typically subjected to a succession of six cleaning and rinsing operations as described in Table A below. (Contact with ambient temperature tap water before any of the stages in Table A is sometimes used also; when used, this stage is often called a "vestibule" to the numbered stages.) WO 96/19553 PCT/US95/16014 Table A STAGE NUMBER ACTION ON SURFACE DURING STAGE Aqueous Acid Precleaning Aqueous Acid and Surfactant Cleaning Tap Water Rinse Mild Acid Postcleaning, Conversion Coating, or Tap Water Rinse Tap Water Rinse Deionized ("PI") Water Rinse It is currently possible to produce a can which is satisfactorily mobile and to which subsequently applied inks and/or lacquers have adequate adhesion by using suitable surfactants either in Stage 4 or Stage 6 as noted above. Preferred treatments for use in Stage 4 as described above have been developed and are described in U. S. Patents 5,030,323 and 5,064,500. With these treatments, a metallic element (not necessarily or even usually in elemental form) is incorpor¬ ated into the lubricant and surface conditioning layer formed.

Experience with prolonged practical use of lubricant and surface condition¬ er forming treatments that incorporate metal into the surface conditioner layer formed has revealed that they are susceptible to the development of at least one separate impurity phase, commonly called "sludge" or some similar term. The sludge is usually sticky, so that small particles of it easily adhere to the contain¬ ers being treated, and if they do so can cause an undesirable phenomenon called "metal exposure", a failure of the subsequently applied interior sanitary lacquer to completely isolate the beverage product contained in the aluminum can from contact with the metal can body. Therefore, if a sufficient amount of sludge forms, it must be removed before continuing with can conditioning. Be¬ cause of the tackiness of the.siudge, it is difficult to remove satisfactorily, so that minimizing and, if possible, preventing formation of the sludge is one of the ob¬ jects of this invention.

WO 96/19553 PCT/US95/16014 DESCRIPTION OF THE INVENTION Other than in the claims and the operating examples, or where otherwise expressly indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in ail instances by the s term "about" in describing the broadest scope of the invention. Practice within the numerical limits given, however, is generally preferred. Also, unless other¬ wise specified, all descriptions of components of compositions by percentages, "parts", or the like refer to weight or mass of the component compared with the total.

io In accordance with this invention, it has been found that a lubricant and surface conditioner applied to aluminum cans after washing enhances their mo¬ bility and, in a preferred embodiment, improves their water film drainage and evaporation characteristics as to enable lowering the temperature of a drying oven by from about 25° to about 100° F without having any adverse effect on the is label printing process. The lubricant and surface conditioner reduces the coeffi¬ cient of static friction on the outside surface of the cans, enabling a substantial increase in production line speeds, and in addition, provides a noticeable im¬ provement in the rate of water film drainage and evaporation resulting in savings due to lower energy demands while meeting quality control requirements.

More particularly, in accordance with one preferred embodiment of this in¬ vention, it has been found that application of a thin organic film to the outside sur¬ face of aluminum cans serves as a lubricant inducing thereto a lower coefficient of static friction, which consequently provides an improved mobility to the cans, and also increases the rate at which the cans may be dried and still pass the quality control column strength pressure test. It has also been found that the de¬ gree of improved mobility and drying rate of the cans depends on the thickness or amount of the organic film, and on the chemical nature of the material applied to the cans.

The lubricant and surface conditioner for aluminum cans in accordance ,30 with this invention may, for example, be selected from water-soluble alkoxylated surfactants such as organic phosphate esters; alcohols; fatty acids including mono-, di-, tri-, and poly-acids; fatty acid derivatives such as salts, hydroxy acids, WO 96/19553 PCT/US95/16014 amides, esters, ethers and derivatives thereof; and mixtures thereof.

The lubricant and surface conditioner for aluminum cans in accordance with this invention in one embodiment preferably comprises a water-soluble de¬ rivative of a saturated fatty acid such as an ethoxylated stearic acid or an eth- s oxylated isostearic acid, or alkali metal salts thereof such as polyoxyethylated stéarate and polyoxyethylated isostearate. Alternatively, the lubricant and sur¬ face conditioner for aluminum cans may comprise a water-soluble alcohol having at least about 4 carbon atoms and may contain up to about 50 moles of ethylene oxide. Excellent results have been obtained when the alcohol comprises poly- oxyethylated oleyl alcohol containing an average of about 20 moles of ethylene oxide per mole of alcohol.

In another preferred aspect of this invention, the organic material em¬ ployed to form a film on an aluminum can following alkaline or acid cleaning and prior to the last drying of the exterior surface prior to conveying comprises a is water-soluble organic material selected from a phosphate ester, an alcohol, fatty acids including mono-, di-, tri-, and poly-acids fatty acid dérivâtes including salts, hydroxy acids, amides, alcohols, esters, ethers and derivatives thereof and mix¬ tures thereof. Such organic material is preferably part of an aqueous solution comprising water-soluble organic material suitable for forming a film on the clean- ed aluminum can to provide the surface after drying with a coefficient of static friction not more than 1.5 and that is less than would be obtained on a can sur¬ face of the same type without such film coating.

In one embodiment of the invention, water solubility can be imparted to organic materials by alkoxylation, preferably ethoxylation, propoxylation or mix- ture thereof. However, non-alkoxylated phosphate esters are also useful in the present invention, especially free acid containing or neutralized mono-and diest- ers of phosphoric acid with various alcohols. Specific examples include Tryfac® 5573 Phosphate Ester, a free acid containing ester available from Henkel Corp.; and Triton® H-55, Triton® H-66, and Triton® QS-44, all available from Union so Carbide Corporation.

Preferred non-ethoxylated alcohols include the following classes of al¬ cohols:

WO 96/19553 PCT/US95/16014 Suitable monohydric alcohols and their esters with inorganic acids include water soluble compounds containing from 3 to about 20 carbons per molecule.

Specific examples include sodium lauryl sulfates such as Duponol® WAQ and Duponol® QC and Duponol® WA and Duponol® C available from Witco Corp.

s and proprietary sodium alkyl sulfonates such as Alkanol®189-S available from E.I. du Pont de Nemours & Co.

Suitable polyhydric alcohols include aliphatic or arylalkyl polyhydric alco¬ hols containing two or more hydroxy! groups. Specific examples include glycer¬ ine, sorbitol, mannitol, xanthan gum, hexylene glycol, gluconic acid, gluconate io salts, glucoheptonate salts, pentaerythritol and derivatives thereof, sugars, and alkylpolyglycosides such as APG®300 and APG®325, available from Henkel Corp. Especially preferred polyhydric alcohols include triglycerols, especially glycerine or fatty acid esters thereof such as castor oil triglycerides.

In accordance with the present invention, we have discovered that em- is ploying alkoxylated, especially ethoxylated, castor oil triglycerides as lubricants and surface conditioners results in further improvements in can mobility espe¬ cially where operation of the can line is interrupted causing the cans to be ex¬ posed to elevated temperatures for extended periods. Accordingly, especially preferred materials include Trylox® 5900, Trylox® 5902, Trylox® 5904, Trylox® 5906, Trylox® 5907, Trylox® 5909, Trylox® 5918, and hydrogenated castor oil derivatives such as Trylox® 5921 and Trylox® 5922, all available from Henkel Corp.

Preferred fatty acids include butyric, valeric, caproic, caprylic, capric, pel- argonic, lauric, myristic, palmitic, oleic, stearic, linoleic, and ricinoleic acids; ma- Ionic, succinic, glutaric, adipic, maleic, tartaric, gluconic, and dimer acids; and salts of any of these; iminodipropionate salts such as Amphoteric N and Am¬ photeric 400 available from Exxon Chemical Co.; sulfosuccinate derivatives such as Texapon®SH-135 Special and Texapon®SB-3, available from Henkel Corp.; citric, nitrilotriacetic, and trimellitic acids; Cheelox® HEEDTA, N-(hydroxyethyl)- ethylenediaminetriacetate, available from GAF Chemicals Corp.

Preferred amides generally include amides or substituted amides of car- boxylic acids having from four to twenty carbons. Specific examples are Alkam- WO 96/19553 PCT/US95/16014 ide® 1.203 lauric monoethanolamide, Alkamide® L7DE lauric/myristic alkanol- amide, Alkamide® DS 280/s stearic diethanoiamide, Alkamide® CD coconut di- ethanolamide, Alkamide® DIN 100 lauric/linoleic diethanoiamide, Alkamide® DIN 295/s iinoleic diethanoiamide, Alkamide® DL 203 lauric diethanoiamide, all avail- able from Rhone-Poulenc; Monamid® 150-MW myristic ethanolamide, Monam- id® 150-CW capric ethanolamide, Monamid® 150-IS isostearic ethanolamide, all available from Mona Industries Inc.; and Ethomid® HT/23 and Ethomid® HT60 polyoxyethylated hydrogenated tallow amines, available from Akzo Chemi¬ cals Inc.

u Preferred anionic organic derivatives generally include sulfate and sulfo¬ nate dérivâtes of fatty acids including sulfate and sulfonate derivatives of natural and synthetically derived alcohols, acids and natural products. Specific examp¬ les include: dodecyl benzene sulfonates such as Dowfax® 2A1, Dowfax® 2AO, Dowfax® 3BO, and Dowfax® 3B2, all available from Dow Chemical Co.; Lomar® is LS condensed naphthalene sulfonic acid, potassium salt available from Henkel Corp.; sulfosuccinate derivatives such as Monamate® CPA sodium sulfosuccin- ate of a modified alkanolamide, Monamate® LA-100 disbdium lauryl sulfosuccin¬ ate, all available from Mona Industries; Triton® GR-5M sodium dioctylsulfosuc- cinate, available from Union Carbide Chemical and Plastics Co.; Varsulf® SBFA 30, fatty alcohol ether sulfosuccinate, Varsulf® SBL 203, fatty acid alkanolamide sulfosuccinate, Varsulf® S1333, ricinoleic monoethanolamide sulfosuccinate, all available from Sherex Chemical Co., Inc.

Another preferred group of organic materials comprise water-soluble al- koxylated, preferably ethoxylated, propoxylated, or mixed ethoxylated and pro- poxylated materials, most preferably ethoxylated, and non-ethoxylated organic materials selected from amine salts of fatty acids including mono-, di-, tri-, and poly-acids, amino fatty acids, fatty amine N-oxides, and quaternary salts, and water soluble polymers.

Preferred amine salts of fatty acids include ammonium, quaternary am- monium, phosphonium, and alkali metal salts of fatty acids and derivatives there¬ of containing up to 50 moles of alkylene oxide in either or both the cationic or an¬ ionic species. Specific examples include Amphoteric N and Amphoteric 400 im- WO 96/19553 PCT/US95/16014 inodipropionate sodium salts, available from Exxon Chemical Co.; Deriphat® 154 disodium N-tallow-beta iminodipropionate and Deriphat® 160, disodium N-lauryl- beta iminodipropionate, available from Henkel Corp.

Preferred amino acids include alpha and beta amino acids and diacids and salts thereof, including alkyl and alkoxyiminodipropionic acids and their salts and sarcosine derivatives and their salts. Specific examples include Armeen® Z, N-coco-beta-aminobutyric acid, available from Akzo Chemicals Inc.; Ampho¬ teric N, Amphoteric 400, Exxon Chemical Co.; sarcosine (N-methyl glycine); hy- droxyethyl glycine; Hamposyl® TL-40 triethanolamine lauroyl sarcosinate, Ham- io posyl® O oleyl sarcosinate, Hamposyl® AL-30 ammoniumlauroyl sarcosinate, Hamposyl® L lauroyl sarcosinate, and Hamposyl® C cocoyl sarcosinate, all available from W.R. Grace & Co.

Preferred amine N-oxides include amine oxides where at least one alkyl substituent contains at least three carbons and up to 20 carbons. Specific ex- is amples include Aromox® C/12 bis-(2-hydroxyethyl)cocoalkylamine oxide, Aro- mox® T/12 bis-{2-hydroxyethyl)tallowalkylamine oxide, Aromox® DMC dimethyl- cocoalkylamine oxide, Aromox® DMHT hydrogenated dimethyltallowalkylamine oxide, Aromox®DM-16 dimethylheaxdecylalkylamine oxide, all available from Ak¬ zo Chemicals Inc.; and Tomah® AO-14-2 and Tomah® AO-728 available from Exxon Chemical Co.

Preferred quaternary salts include quaternary ammonium derivatives of fatty amines containing at least one substituent containing from 12 to 20 carbon atoms and zero to 50 moles of ethylene oxide and/or zero to 15 moles of propyl¬ ene oxide where the counter ion consists of halide, sulfate, nitrate, carboxylate, alkyl or aryl sulfate, alkyl or aryl sulfonate or derivatives thereof. Specific examp¬ les include Arquad® 12-37Wdodecyltrimethylammonium chloride, Arquad® 18- octadecyltrimethylammonium chloride, Arquad® 210-50 didecyldimethylam- monium chloride, Arquad® 218-100 dioctadecyldimethylammonium chloride, Ar¬ quad® 316(W) trihexadecylmethylammonium chloride, Arquad® B-100 benzyldi- methyKC.alkylammonium chloride, Ethoquad® C/12 cocomethyl[POE(2)]am- monium chloride, Ethoquad® C/25 cocomethyl[POE(15)]ammonium chloride, Ethoquad® C/12 nitrate salt, Ethoquad® T/13 Acetate tris(2-hydroxyethyl)tallow- WO 96/19553 PCT/US95/16014 alkyl ammonium acetate, Duoqaud® T-50 N.N.N'.N'.N'-pentamethyl-N-tallow-I.S- diammonium dichloride, Propoquad® 2HT/11 di(hydrogenated tallowalkyl)(2-hy- droxy-2-methylethyl)methylammonium chloride, Propoquad®T/12 tallowalkyi- methyl-bis-(2-hydroxy-2-methylethyl)ammonium methyl sulfate, all available from Akzo Chemicals Inc.; Monaquat® P-TS stearamidopropyl PG-dimonium chloride phosphate, available from Mona Industries Inc.; Chemquat® 12-33 lauryltrimeth- ylammonium chloride, Chemquat® 16-50 Cetyltrimethylammonium chloride avail¬ able from Chemax Inc.; and tetraethylammonium pelargonate, laurate, myristate, oleate, stéarate or isostearate.

io Preferred water-soluble polymers include homopolymers and heteropoly- mers of ethylene oxide, propylene oxide, butylène oxide, acrylic acid and its de¬ rivatives, maleic acid and its derivatives, vinyl phenol and its derivatives, and vin¬ yl alcohol. Specific examples include Carbowax® 200, Carbowax® 600, Carbo- wax® 900, Carbowax® 1450, Carbowax® 3350, Carbowax® 8000, and Corn- is pound 20M, all available from Union Carbide Corp.; Pluronic® L61, Pluronic® L81, Pluronic® 31R1, Pluronic® 25R2, Tetronic® 304, Tetronic® 701, Tetronic® 908, Tetronic® 90R4, and Tetronic® 150R1, all available from BASF Wyandotte Corp.; Acusol® 41 ON sodium salt of polyacrylic acid, Acusol® 445 polyacrylic acid, Acusol® 460ND sodium salt of maleic acid/olefin copolymer, and Acusol® so 479N sodium salt of acrylic acid/maleic acid copolymer, all available from Rohm & Haas Company; and N-methylglucamine adducts of polyvinylphenol and N- methylethanolamine adducts of polyvinylphenol.

Additional improvements are achieved by combining with the organic material(s) noted above an inorganic material selected from metallic or ionic zir- zs conium, titanium, cerium, aluminum, iron, vanadium, tantalum, niobium, molyb¬ denum, tungsten, hafnium or tin to produce a film combining one or more of these metals with one or more of the above-described organic materials. A thin film is produced having a coefficient of static friction that is not more than 1.5 and is less than the coefficient without such film, thereby improving can mobility in high speed conveying without interfering with subsequent lacquering, other pain¬ ting, printing, or other similar decorating of the containers. This type of lubricant and suface conditioner is especially preferred when used in Stage 4 as defined WO 96/19553 PCT/US95/16014 above.

The technique of incorporating such inorganic materials is described, in particular detail with reference to zirconium containing materials, in U.S. Patents 5,030,323 of July 9,1991 and 5,064,500 of November 12,1991, the entire dis- closures of which, to the extent not inconsistent with any explicit statement herein, are hereby incorporated herein by reference. The substitution of other metallic materials for those taught explicitly in one of these patents is within the scope of those skilled in the art.

In a further preferred embodiment of the process of the present invention, io in order to provide improved water solubility, especially for the non-ethoxylated organic materials described herein, and to produce a suitable film on the can sur¬ face having a coefficient of static friction not more than 1.5 after drying, one em¬ ploys a lubricant and surface conditioner forming composition that includes one or more surfactants, preferably alkoxylated and most preferably ethoxylated, is along with such non-ethoxylated organic material to contact the cleaned can sur¬ face prior to final drying and conveying. Preferred surfactants include ethoxylat¬ ed and non-ethoxylated sulfated or sulfonated fatty alcohols, such as lauryl and coco alcohols. Suitable are a wide class of anionic, non-ionic, cationic, or am¬ photeric surfactants. Alkyl polyglycosides such as C8 - C1B alkyl polyglycosides having average degrees of polymerization between 1.2 and 2.0 are also suitable.

Other classes of surfactants suitable in combination are ethoxylated nonyl and octyl phenols containing from 1.5 to 100 moles of ethylene oxide, preferably a nonylphenol condensed with from 6 to 50 moles of ethylene oxide such as Ige- pal® CO-887 available from Rhone-Poulenc; alkyl/aryl polyethers, for example, Triton® DF-16; and phosphate esters of which Triton® H-66 and Triton® QS-44 are examples, all of the Triton® products being available from Union Carbide Co., and Ethox® 2684 and Ethfac® 136, both available from Ethox Chemicals Inc., are representative examples; polyethoxylated and/or polypropoxylated de¬ rivatives of linear and branched alcohols and derivatives thereof, as for example so Trycol® 6720 (Henkel Corp.), Surfonic® LF-17 (Huntsman Chemical Co.) and Antarox® LF-330 (Rhone-Poulenc); sulfonated derivatives of linear or branched aliphatic alcohols, for example, Neodol® 25-3S (Shell Chemical Co.); sulfonated WO 96/19553 PCT/US95/16014 aryl derivatives, for example, Dyasulf® 9268-A, Dyasulf® C-70, Lomar® D (Henkel Corp.) and Dowfax® 2A1 (Dow Chemical Co.); and ethylene oxide and propylene oxide copolymers, for example, Pluronic® L-61, Pluronic® 81, Pluronic® 31R1, Tetronic® 701, Tetronic® 90R4 and Tetronic® 150R1, all s available from BASF Corp.

Surprisingly, it has been found that surfactants containing a phenanthrene ring structure, which is to be understood herein as contained not only in phenan¬ threne itself but in molecules made by hydrogenating phenanthrene to any de¬ gree not sufficient to break any of the three rings present in phenanthrene, are io disadvantageous constituents of the lubricant and surface conditioner forming composition, at least if this composition also contains any inorganic material selected from metallic or ionic zirconium, titanium, cerium, aluminum, iron, va¬ nadium, tantalum, niobium, molybdenum, tungsten, hafnium or tin as described above. The formation of sludge is notably increased when such surfactants are is present together with any of these inorganic materials. It has also been found that the tendency to sludge formation can usefully be tested in a laboratory, without the need for actual can processing, by deliberately adding such soils as aluminum fines, soluble aluminum-containing species, drawing oils, and cleaner surfactants to the lubricant and surface conditioner forming composition to be 2o tested for resistance to sludging, then passing the deliberately soiled composition through a spraying stage repeatedly and observing whether any dry floe is visible on the head of foam that forms in the container into which the spray drains. The presence or absence of dry floe in this test indicates, with at least rough quanti¬ tative correlation, whether or not sludge will likely become a problem in operating the lubricant and surface conditioner forming composition thus tested, and if so, the extent of the sludge formation likely to be observed in practical use.

Surfactants with a phenanthrene ring structure, especially abietate, hy- drogenated abietate, and alkoxylated abietate surfactants derived from natural rosin, are very commonly used now in the cleaning stage of container process- so ing, before contact with any lubricant and surface conditioner forming composi¬ tion, for example in Stage 2 as shown in Table A. Inasmuch as carry-over of some of the cleaner surfactants into the compositions used for later stages of WO 96/19553 PCT/US95/16014 treatment can not be entirely avoided in practical high speed and high volume can processing, such cleaner surfactants should be used only with care and in limited amounts if at all in any processing stage prior to a lubricant and surface conditioner forming composition that includes inorganic material selected from s metallic or ionic zirconium, titanium, cerium, aluminum, iron, vanadium, tantalum, niobium, molybdenum, tungsten, hafnium or tin as described above.

More specifically, it is preferred, with increasing preference in the order given and independently for each composition concerned, that (i) any lubricant and surface conditioner forming composition that contains inorganic material se- io lected from metallic or ionic zirconium, titanium, cerium, aluminum, iron, vanadi¬ um, tantalum, niobium, molybdenum, tungsten, hafnium or tin as described above and (II) any cleaner or rinse composition that is contacted with the contain¬ ers to be provided with a lubricant and surface conditioner layer before the con¬ tainers are brought into contact with the lubricant and surface conditioner forming is composition, should contain not more than 5, 4, 3, 2,1, 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.04, 0.03, 0.02, 0.01, 0.005, 0.004, 0.003, 0.002, 0.001, 0.0005, 0.0004, 0.0003,0.0002, 0.0001, 0.00005, 0.00004, 0.00003, 0.00002, or 0.00001 % in total of carbon atoms that are part of a phenanthrene ring structure as defined above. The minimization of concentration of phenanthrene ring containing com- pounds is particularly advantageous in connection with the use of lubricant and surface conditioner forming compositions as taught in U. S. Patents 5,030,323 and 5,064,500 Phenanthrene ring containing nonionic surfactants have been extensively used for at least the last several years for cleaning aluminum containers, be- cause they are highly effective in removing some of the kinds of organic soils of¬ ten found on such containers. However, it has now been found that alkyl phenol based nonionic surfactants can satisfactorily replace phenanthrene ring contain¬ ing surfactants for this purpose, and the alkyl phenol based surfactants do not promote sludge formation in metal containing lubricant and surface conditioner so forming compositions as do phenanthrene ring containing surfactants. A partic¬ ularly preferred combination of surfactants for a cleaner stage preceding a metal containing lubricant and surface conditioner forming compositions comprises, WO 96/19553 PCTAJS95/16014 more preferably consists essentially of, or still more preferably consists of:

(A) a component of nonionic surfactants selected from the group consisting of surfactants corresponding to the chemical formula:

RiO-(CnH2nO)6H where a is 0 or 1 ; R represents an alkyl moiety that may be branched or unbranched and saturated or unsaturated but does not include any aryl group and the sum of a plus the number of carbon atoms in R is from 10 - io 22, more preferably from 12 - 20, or still more preferably from 14 -18; n is an integer that is at least 2 and is not greater than 4, more preferably not greater than 3, most preferably 2 and may be different from one CnH2nO group to another in the same molecule; and b is an integer, the value or values of b being selected such that the hydrophile-lipophile bal- ance ("HLB") of the total component is, with increasing preference in the order given, not less than 8,10,10.5,11.0,11.3, li.5,11.7,11.8,11.9, 12.0, or 12.1 and independently is, with increasing preference in the order given, not more than 20,18,16,15,14,13.7,13.5,13.3,13.1,12.9,12.8, 12.7,12.6,12.5,12.4, or 12.3; and (B) a component of nonionic surfactants selected from the group consisting of surfactants corresponding to the chemical formula R'-0-(CnH2nO)eH, where R' represents an alkyl moiety that may be branched or unbranched and saturated or unsaturated but does not include any aryl group and that has from 4-16, more preferably from 6-14, still more preferably from 8 - 10, most preferably 9, carbon atoms; O represents a phenylene group; n is an integer that is at least 2 and is not greater than 4, more preferably not greater than 3, most preferably 2; and c is an integer, the value or val¬ ues of c being selected such that the HLB of the total component is, with increasing preference in the order given, not less than 9,10.0,10.6 11.2, so 11.7,12.2,12.5,12.7,12.9,13.0,13.1,13.2, or 13.3 and independently is, with increasing preference in the order given, not more than 21,19,17, 16,15,14.7,14.5,14.3,14.1,13.9,13.8,13.7,13.6, or 13.5.

Independently, the ratio of component (A) to component (B) in the mixture preferably is, with increasing preference in the order given, not less than 0.1, 0.2, WO 96/19553 PCT/US95/16014 0.3, 0.4, 0.5, 0.55, 0.59, 0.63, 0.60, 0.62, 0.64, 0.66, 0.67, 0.68, 0.69, 0.70, or 0.71 and independently preferably is, with increasing preference in the order given, not greater than 10, 5,4, 3,2,1.5,1.2,1.1,1.0, 0.9, 0.85, 0.83, 0.81, 0.80, 0.79, 0.78, 0.77, 0.76, 0.75, 0.74, 0.73, or 0.72.

The lubricant and surface conditioner for aluminum cans in accordance with this invention may comprise a phosphate acid ester or preferably an ethoxyl- ated alkyl alcohol phosphate ester. Such phosphate esters are commercially available as Gafac® PE 510 from GAF Corporation, Wayne, NJ, and as Ethfac® 136 and 161 and Ethox™ 2684 from Ethox Chemicals, Inc., Greeneville, SC. In general, the organic phosphate esters may comprise alkyl and aryl phosphate esters with and without ethoxylation.

The lubricant and surface conditioner forming composition for aluminum cans may be applied to the cans during their wash cycle, during one of their treatment cycles such as cleaning or conversion coating, during one of their wat¬ er rinse cycles, or during their final water rinse cycle. In addition, the lubricant and surface conditioner may be applied to the cans after their final water rinse cycle, i.e., prior to oven drying, or after oven drying, by fine mist application from water or another volatile non-inflammable solvent solution. It has been found that the lubricant and surface conditioner is capable of depositing on the alumin¬ um surface of the cans to provide them with the desired characteristics. The lub¬ ricant and surface conditioner may be applied by spraying and reacts with the aluminum surface through chemisorption or physiosorption to provide it with the desired film.

Generally, in the cleaning process of the cans, after the cans have been washed, they are typically exposed to an acidic water rinse. In accordance with this invention, the cans may thereafter be treated with a lubricant and surface conditioner comprising an anionic surfactant such as a phosphate acid ester. In such case, the pH of the treatment system is important and generally should be acidic, that is between about 1 and about 6.5, preferably between about 2.5 and about 5. If the cans are not treated with the lubricant and surface conditioner of this invention next after the acidic water rinse, the cans are often exposed to a tap water rinse and then to a deionized water rinse. In such event, the deionized WO 96/19553 PCT/US95/16014 water rinse solution is prepared to contain the lubricant and surface conditioner forming composition of this invention, which may comprise a nonionic surfactant selected from the aforementioned polyoxyethylated alcohols or polyoxyethylated fatty acids, or any of the other suitable materials as described above. After such treatment, the cans may be passed to an oven for drying prior to further process¬ ing.

The amount of lubricant and surface conditioner to be applied to the cans should be sufficient to reduce the coefficient of static friction on the outside sur¬ face of the cans to a value of about 1.5 or lower, and preferably to a value of about 1 or lower. Generally speaking, such amount should be on the order of from about 3 mg/m2 to about 60 mg/m2 of lubricant and surface conditioner on the outside surface of the cans.

Another embodiment of the present invention comprises the application of the technology described herein to providing lubricants and surface condition- is ers for tin- cans especially to aid in dewatering and drying of such cans. The compositions and methods described herein are suitable for that purpose.

For a fuller appreciation of the invention, reference may be made to the following examples, which are intended to be merely descriptive, illustrative, and not limiting as to the scope of the invention.

Example i This example illustrates the amount of aluminum can lubricant and surface conditioner necessary to improve the mobility of the cans through the tracks and printing stations of an industrial can manufacturing facility, and also shows that the lubricant and surface conditioner does not have an adverse effect on the ad- hesion of labels printed on the outside surface as well as of lacquers sprayed on the inside surface of the cans.

Uncleaned aluminum cans obtained from an industrial can manufacturer were washed clean with an alkaline cleaner available from the Parker Amchem Division, Henkel Corporation, Madison Heights, Ml, employing that company's so Ridoline® 3060/306 process. The cans were washed in a laboratory Miniwasher processing 14 cans at a time. The cans were treated with different amounts of lubricant and surface conditioner in the final rinse stage of the washer and then WO 96/19553 PCT/US95/16014 dried in an oven. The lubricant and surface conditioner comprised about a 10% active concentrate of polyoxyethylated isosterate, an ethoxylated nonionic sur¬ factant, available under the tradename Ethox™ MI-14 from Ethox Chemicals, Inc., Greenville, SC. The treated cans were returned to the can manufacturer for s line speed and printing quality evaluations. The printed cans were divided into two groups, each consisting of 4 to 6 cans. All were subjected for 20 minutes to one of the following adhesion test solutions:

Test Solution A: 1% Joy® (a commercial liquid dishwashing detergent, Procter and Gamble Co.) solution in 3:1 deionized watertap water at a tempera- io tureof180oF.

Test Solution B: 1% Joy® detergent solution in deionized water at a tem¬ perature of 212° F.

After removing the printed cans from the adhesion test solution, each can was cross-hatched using a sharp metal object to expose lines of aluminum which is showed through the paint or lacquer, and tested for paint adhesion. This test in¬ cluded applying Scotch® transparent tape No. 610 firmly over the cross-hatched area and then drawing the tape back against itself with a rapid pulling motion such that the tape was pulled away from the cross-hatched area. The results of the test were rated as follows: 10, perfect, when the tape did not peel any paint from the surface; 8, acceptable; and 0, total failure. The cans were visually ex¬ amined for any print or lacquer pick-off signs.

In addition, the cans were evaluated for their coefficient of static friction using a laboratory static friction tester. This device measures the static friction associated with the surface characteristics of aluminum cans. This is done by zs using a ramp which is raised through an arc of 90° by using a constant speed motor, a spool and a cable attached to the free swinging end of the ramp. A cradle attached to the bottom of the ramp is used to hold 2 cans in horizontal po¬ sition approximately 0.5 inches apart with the domes facing the fixed end of the ramp. A third can is laid upon the 2 cans with the dome facing the free swinging so end of the ramp, and the edges of all 3 cans are aligned so that they are even with each other.

As the ramp begins to move through its arc, a timer is automatically actu- WO 96/19553 PCT/US95/16014 ated. When the ramp reaches the angle at which the third can slides freely from the 2 lower cans, a photoelectric switch shuts off the timer. It is this time, record¬ ed in seconds, which is commonly referred to as "slip time". The coefficient of static friction is equal to the tangent of the angle swept by the ramp at the time the can begins to move.

The average values for the adhesion test and coefficient of static friction evaluation results are summarized in Table 1 which follows:

Table 1 TestNo. Lubricant andSurfaceConditionerConcentrate(%/voD Adhesion EvaluationTestSolu¬tion OSW ISW ID Coefficient ofStaticFriction 1 Control (notreatment) 1.42 2 0.1 B 10 10 10 0.94 3 0.25 A 10 10 10 _ 4 0.5 B 9.5* 10 10 0.80 0.75 A 10 10 10 0.63 6 1.0 B 10 10 10 0.64 7 2.0 A 10 10 10 0.56 8 5.0 B 10 10 10 0.55 9 10.0 A 9.8* 10 10 0.56 "Little pick-ofFwas visually noticed on the outside walls, mainly at the contact marks.

In Table 1, "OSW" stands for outside sidewall, "ISW stands for inside sidewall, and "ID" stands for inside dome.

In brief, it was found that the lubricant and surface conditioner forming composition as applied to the cleaned aluminum cans provided improved mobility to the cans even at very low active ingredient concentrations, and it had no ad¬ verse effect on either adhesion of label print or internal lacquer tested even at WO 96/19553 PCT/US95/16014 to 100 times the required use concentration to reduce the coefficient of static fric¬ tion of the cans.

Example II This example illustrates the use of the aluminum can lubricant and surface s conditioner of Example I in an industrial can manufacturing facility when passing cans through a printing station at the rate of 1260 cans per minute.

Aluminum can production was washed with an acidic cleaner (Ridoline ® 125 CO, available from the Parker Amchem Division, Henkel Corporation, Madi¬ son Heights, Ml), and then treated with a non-chromate conversion coating (Alo- dine® 404, also available from the Parker Amchem Division, Henkel Corporation, Madison Heights, Ml). The aluminum can production was then tested for "slip" and the exterior of the cans were found to have a static coefficient of friction of about 1.63. During processing of these cans through a printer station, the cans could be run through the printer station at the rate of 1150 to 1200 cans per min¬ is ute without excessive "trips", i.e., improperly loaded can events. In such case, the cans are not properly loaded on the mandrel where they are printed. Each "trip" causes a loss of cans which have to be discarded because they are not ac¬ ceptable for final stage processing.

About 1 ml/liter of aluminum can lubricant and surface conditioner was added to the deionized rinse water system of the can washer, which provided a reduction of the static coefficient of friction on the exterior of the cans to a value of 1.46 or a reduction of about 11 percent from their original value. After passing the cans through the printer, it was found that the adhesion of both the interior and exterior coatings were unaffected by the lubricant and surface conditioner.

In addition, the printer speed could be increased to its mechanical limit of 1250 to 1260 cans per minute without new problems.

In similar fashion, by increasing the concentration of the aluminum can lubricant and surface conditioner forming composition in the deionized rinse wa¬ ter system, it was possible to reduce the coefficient of static friction of the cans so by 20 percent without adversely affecting the adhesion of the interior and exterior coatings of the cans. Further, it was possible to maintain the printer speed con¬ tinuously at 1250 cans per minute for a 24-hour test period.

WO 96/19553 PCT/US95/16014 Example 111 This example illustrates the use of other materials as the basic component for the aluminum can lubricant and surface conditioner.

Aluminum cans were cleaned with an alkaline cleaner solution having a pH of about 12 at about 105oF for about 35 seconds. The cans were rinsed, and then treated with three different lubricant and surface conditioners comprising various phosphate ester solutions. Phosphate ester solution 1 comprised a phosphate acid ester (available under the tradename Gafac® PE 510 from GAP Corporation, Wayne, N J) at a concentration of 0.5 g/l. Phosphate ester solution 2 comprised an ethoxylated alkyl alcohol phosphate ester (available under the tradename Ethfao® 161 from Ethox Chemicals, Inc., Greenville, SC) at a concen¬ tration of 0.5 g/l. Phosphate ester solution 3 comprised an ethoxylated alkyl alco¬ hol phosphate ester (available under the tradename Ethfac® 136 from Ethox Chemicals, Inc., Greenville, SC) at a concentration of 1.5 g/l.

The mobility of the cans in terms of coefficient of static friction was evaluated and found to be as follows:

Phosphate EsterSolution pH Coefficient of StaticFriction 1 3.6 0.47 2 3.3 0.63 3 2.6 0.77 None — 1.63 The aforementioned phosphate ester solutions all provided an acceptable mobility to aluminum cans, but the cans were completely covered with "water- break". It is desired that the cans be free of water-breaks, i.e., have a thin, continuous film of water thereon, because otherwise they contain large water droplets, and the water film is non-uniform and discontinuous. To determine whether such is detrimental to printing of the cans, they were evaluated for adhe¬ sion. That is, the decorated cans were cut open and boiled in a 1 % liquid dish¬ washing detergent solution (Joy®) comprising 3:1 deionized water:tap water for ten minutes. The cans were then rinsed in deionized water and dried. As in Ex- WO 96/19553 PCT/US95/16014 ample I, eight cross-hatched scribe lines were cut into the coating of the cans on the inside and outside sidewalls and the inside dome. The scribe lines were taped over, and then the tape was snapped off. The cans were rated for ad¬ hesion values. The average value results are summarized in Table 2.

Table 2 Phosphate esterSolution Adhesion Rating OSW ISW ID Control 10 10 1 9.8 6.8 1.0 2 9.8 10 In Table 2, "OSW" stands for "outside sidewall", "ISW" stands for "inside is sidewall", and "ID" stands for "inside dome".

For the control, it was observed that there was no pick-off (loss of coating adhesion) on either the outside sidewall, the inside sidewall or the inside dome of the cans.

For phosphate ester solution 1, it was observed that there was almost no pick-off on the outside sidewall, substantial pick-off on the inside sidewall, and complete failure on the inside dome of the cans.

For phosphate ester solution 2, it was observed that there was almost no pick-off on the outside sidewall, and no pick-off on the inside sidewall and no pick-off on the inside dome of the cans.

For phosphate ester solution 3, it was observed that there was no pick-off on the outside sidewall, the inside sidewall, and the inside dome of the cans.

Example IV This example illustrates the effect of the lubricant and surface conditioner of this invention on the water draining characteristics of aluminum cans treated so therewith.

Aluminum cans were cleaned with acidic cleaner (Ridoline® 125 CO fol- WO 96/19553 PCT/US95/16014 lowed by Alodine ® 404 treatment or Ridoline® 125 CO only) or with an alkaline cleaner solution (Ridoline® 3060/306 process), all the products being available from the Parker Amchem Division, Henkel Corporation, Madison Heights, Ml, and then rinsed with deionized water containing about 0.3% by weight of a lubricant and surface conditioner of this invention. After allowing the thus-rinsed cans to drain for up to 30 seconds, the amount of water remaining on each can was de¬ termined. The same test was conducted without the use of the lubricant and sur¬ face conditioner. The results are summarized in Table 3.

Table 3 Drain Time,Seconds Water Remaining, Grams per Can With DI Water With 0.3 % Conditioner 6 2.4-3.0 not determined 12 2.1-3.5 2.8 18 2.2 - 3.5 2.3 1.8-3.4 2.3 It was found that the presence of the lubricant and surface conditioner caused the water to drain more uniformly from the cans, and that the cans re¬ mained "water-break" free for a longer time.

Example V This example illustrates the effect of the oven dryoff temperature on the sidewall strength of aluminum cans. This test is a quality control compression test which determines the column strength of the cans by measuring the pres¬ sure at which they buckle. The results are summarized in Table 4.

WO 96/19553 PCT/US95/16014 Table 4 Oven Temperature (0 F) Column Strength (PSI) 86.25 87.75 88.25 89.25 It can be seen from Table 4 that at an oven drying temperature of 380° F, a 2 psi increase was obtained in the column strength test compared to the value obtained at 440° F oven temperature.

The higher column strength test results are preferred and often required because the thin walls of the finished cans must withstand the pressure exerted from within after they are filled with a carbonated solution. Otherwise, cans hav¬ ing weak sidewalls will swell and deform or may easily rupture or even explode.

It was found that the faster water film drainage resulting from the presence there¬ in of the lubricant and surface conditioner composition of this invention makes it possible to lower the temperature of the drying ovens and in turn obtain higher column strength results. More specifically, in order to obtain adequate drying of the rinsed cans, the cans are allowed to drain briefly before entry into the drying ovens. The time that the cans reside in the drying ovens is typically between 2 and 3 minutes, dependent to some extent on the line speed, oven length, and oven temperature. In order to obtain adequate drying of the cans in this time¬ frame, the oven temperature is typically about 440° F. However, in a series of tests wherein the rinse water contained about 0.3 % by weight of a lubricant and surface conditioner of this invention, it was found that satisfactory drying of the cans could be obtained wherein the oven temperature was lowered to 400° F, and then to 370° F, and dry cans were still obtained.

Examples Group VI Uncleaned aluminum cans from an industrial can manufacturer are washed clean in examples Type A with alkaline cleaner available from Parker Amchem Division, Henkel Corporation, Madison Heights, Michigan, employing WO 96/19553 PCT7US95/16014 the Ridoline® 3060/306 process and in Examples Type B with an acidic cleaner, Ridoline® 125 CO from the same company. Following initial rinsing and before final drying, the cleaned cans are treated with a lubricant and surface conditioner comprised of about a 1 % by weight active organic (I) in deionized water as speci- s fied in Table 5 below. In a separate set of examples, following initial rinsing and before final drying, the cleaned cans are treated with a reactive lubricant and sur¬ face conditioner comprised of about a 1% active organic (I) in deionized water plus about 2 gm/l (0.2wt%) of the inorganic (II) as specified in Table 5, below.

In yet another set of examples, following initial rinsing and before final drying, the io cleaned cans are treated with a lubricant and surface conditioner comprised of about 1% active organic (I) in deionized water plus about 0.5% by weight of sur¬ factant (III) specified in Table 5, below. In a further set of examples, following ini¬ tial rinsing and before final drying, the cleaned cans are treated with a reactive lubricant and surface conditioner in deionized water comprised of about 1 % ac- tive organic (I), about 0.2% inorganic (II), about 0.5% surfactant (III) as specified in Table 5, below.

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m u es a o o- oo vo es •s « 1 «s «n x o Œ «s g "S «n <s o X o CQ < CQ < en WO 96/19553 PCT/US95/16014 Example and Comparison Example Group VII Two different surfactant combinations were prepared. The first consisted of SURFONIC™ LF-17 and TRITON™ N-101 in a ratio of 111:156. The second consisted of EMULSOGEN™ TP-2144, TRYCOL™ LF-1, and ANTAROX LF-330 in a ratio of 201:64.5:64.5. All of these tradenamed surfactants are alkyl polyeth- ers, except for TRITON™, which is a nonyl phenol ethoxylate, and EMULSO¬ GEN™ TP-2144, which is ethoxylated rosin and therefore contains a phenan- threne ring structure.

About 0.2 % of each surfactant combination was added to separate batch- io es of aqueous sulfuric and hydrofluoric acids in the amounts used in conventional acid cleaner for aluminum cans, and these acid-surfactant combinations were used as the base treatment liquid for Stage 2 as defined in Table A above. In order to simulate the build-up of lubricant and aluminum containing species that would occur in normal extended use of such a cleaner for processing large vol- i5 umes of aluminum cans, there were also added to these cleaning compositions (i) 2 g/L of a lubricant mixture consisting of 30 parts of DTI™ 5600 M3 cupper lubricant, 37 parts of DTI™ 5600 WB coolant, and 33 parts of Mobil™ 629 hy¬ draulic lubricant (the products including the letters "DTI" in their designations above are commercially available from Diversified Technology Inc., San Antonio, 2o Texas, USA) and (ii) sufficient sodium aluminate to correspond to 1980 parts per million stoichiometric equivalent of aluminum. For further simulation of extended operations, Stage 3 as defined in Table A contained 5 % by volume of the clean¬ er solution in tap water as its treatment liquid, and, in some of the experiments, Stage 4 as defined in Table A, in which the treatment liquid was primarily FIXO- DINE® 500, was "contaminated" with 0.25 or 1.0 % of the cleaner bath, while in other experiments, the Stage 4 treatment liquid was left free from any cleaner bath. (It has been determined by extensive experience that at equilibrium a treat¬ ment liquid which is routinely overflowed by addition of less contaminated solu¬ tion will contain about 5 % by volume of the treatment liquid from the previous so process stage in addition to its nominal, deliberately added constituents. Stages 2 and 3 treatment liquids are normally routinely overflowed, while Stage 4 treat¬ ment liquid normally is not. Therefore, Stage 4 treatment liquid can become ev¬ en more contaminated than would be expected from carry-over of 5 % of the WO 96/19553 PCT/US95/16014 Stage 3 treatment liquid, which would correspond to a content of 0.25 % of the Stage 2 treatment liquid.) In all these experiments, it was observed that the Stage 4 bath developed sludge when the acid cleaning solution containing the second surfactant combi- s nation were used, but remained free from sludge when the acid cleaning solution containing the first surfactant combination was used.

Example and Comparison Example Group VIII These examples and comparison examples were performed on an actual commercial cleaning line, in a plant where the primary materials to be cleaned io were DTI™ 5600 M3 cupper lubricant, DTI™ 5600 WB coolant, and Mobil™ 629 hydraulic lubricant. The cleaner used as Stage 2 in the preferred example ac¬ cording to the invention for this group consisted when fresh of 450 parts of aque¬ ous sulfuric acid with a density of 66° Baume, 93 parts of TRITON™ DF-16 (commercially available from Union Carbide Corp., reported to have an HLB val- i5 ue of 11 .€ and to consist of ethoxylated and then terminally propoxylated linear alcohol molecules with from 8 to 10 carbon atoms in the alcohol residue), 7 parts of PLURAFAC™ D-25 (commercially available from BASF Corp., reported to have an HLB value of 10.0 and to consist of molecules of the same type as de¬ scribed above for TRITON™ DF-16, except that there are from 10 to 16 carbon atoms in the alcohol residue), and 450 parts of water. The Stage 4 treatment li¬ quid when fresh was FIXODINE® 500.

These treatment liquids were operated in actual cleaning, with convention¬ al overflowing and replenishment of the various treatment liquids, of more than 1400 aluminum beverage cans per hour for about seven months of continuous zs operation (except for possible occasional brief line stoppages necessitated by equipment malfunctions or routine maintenance; these are believed not to total more than an average of three days per month). The Stage 2 treatment liquid was maintained at 140 ± 2 0 F and the Stage 4 treatment liquid was maintained at110±1 0F.

During this operation, at intervals the concentrations of free acid and "Re¬ action Product" in the Stage 2 treatment liquid were measured as described in Parker Amchem Technical Process Bulletin No. 971, Revision of April 19, 1989, and the concentrations of free add and "Reaction Product" for the Stage 4 treat- WO 96/19553 PCT/US95/16014 ment liquid were measured as described in Parker Amchem Technical Process Bulletin No. 1373, Revision of September 22,1994. The concentrations of dis¬ solved aluminum in parts per million in the Stage 2 and Stage 4 treatment liquids are known to be within ± 10 % of the value obtained by multiplying the Reaction Product value by 90 for Stage 2 and by 18 for Stage 4. The concentrations of the TRITON™ DF-16 (abbreviated below as "DF-16") and PLURAFAC™ D-25 (abbreviated as "D-25" below) surfactants were calculated from the free acid val¬ ues by assuming that all the free acidity came from complete ionization of the sulfuric acid in the fresh Stage 2 treatment liquid and that the surfactants were present in the same ratios to the sulfuric acid as in the fresh Stage 2 treatment liquid. Some of the more pertinent values are shown in Table 6 below. In all these instances, the Stage 4 treatment liquid remained free from any discernible sludge, either in suspension in the liquid or atop the foam layer that normally is present during steady state operations in the Stage 4 treatment liquid tank.

Table6 Characteristic Value for Characteristic after the FollowingNumber of Days of Operation:

For Stage 2:

Points of Free Acid 16 14 14 14 14 14 ppm of Dissolved Ar3 1080 990 900 1260 990 990 g/L of DF-16 1.74 1.52 1.52 1.52 1.52 1.52 g/LofD-25 0.13 0.11 0.11 0.11 0.11 0.11 For Stage 4:

pH 2.6 2.7 2.7 2.6 2.6 2.6 Points of Free Acid n. m. 1.0 1.0 1.2 1.5 1.5 ppm of Dissolved Ar3 n. m. 252 72 284 306 306 % of Cans That Were Water-Bn iak-Free after Stage 6:

On Exterior 100 100 100 100 100 100 On Interior 90 100 100 100 100 100 WO 96/19553 PCT/US95/16014 In contrast to this, in an otherwise similar production operation in which the Stage 2 treatment liquid contained a surfactant based on ethoxylated rosin acids including a phenanthrene ring structure, solid sludge was observed to ac¬ cumulate atop the foam layer in the Stage 4 treatment liquid tank. From there, i the sludge was occasionally dispersed into various other treatment solutions in the process line and when so dispersed often transferred to the surfaces of the treated cans, causing failures of complete coverage of the can surface by later applied lacquer. Such failures of complete coverage require rejection of the cans in question, and they occurred frequently enough that corrective measures were required to maintain the commercial economic viability of the processing oper¬ ation.

WO 96/19553 PCT/US95/16014 The invention claimed is:

1 A process comprising steps of:

(I) cleaning an aluminum can with an aqueous acidic cleaning solution com¬ prising a surfactant component and s (II) contacting the aluminum can after step (1) with an aqueous lubricant and surface conditioner forming composition, distinct from said aqueous acidic cleaning solution, said aqueous lubricant and surface conditioner compris¬ ing as dissolved, dispersed, or both dissolved and dispersed components therein (i) water-soluble organic material selected from phosphate esters, alcohols, fatty acids including mono-, di-, tri-, and poly-acids; fatty acid de¬ rivatives including salts, hydroxy acids, amides, esters, ethers, and deriva¬ tives thereof, and mixtures thereof, and (ii) at least one of the elements selected from zirconium, titanium, cerium, aluminum, iron, tin, vanadium, tantalum, niobium, molybdenum, tungsten, and hafnium in metallic or ionic is form, wherein the improvement comprises utilizing an aqueous acid cleaning solution that contains not more than about 0.1 % of carbon atoms that are part of phenan- threne rings and an aqueous lubricant and surface conditioner forming composi¬ tion that contains not more than about 0.01 % of carbon atoms that are part of phenanthrene rings.