GB2102838A - Alkaline solutions and processes for cleaning aluminium - Google Patents

Abstract

Alkaline solutions for cleaning aluminium and removing aluminium fines and lubricating oils therefrom comprise from 0.5 to 3 g/l, and preferably from 1 to 2 g/l, of alkali metal hydroxide(s); from 1 to 5 g/l, and preferably from 1.5 to 3 g/l of alkali metal salt(s) of ethylenediamine- tetraacetic acid (EDTA); and from 0.1 to 10 g/l, preferably from 0.2 to 2 g/l, of a surfactant. Concentrates suitable for dilution with water to form the cleaning solutions contain from 25 to 250 g/l of alkali metal hydroxide(s) together with, per part by weight thereof, from 0.33 to 10 and preferably from 0.5 to 6 part(s) by weight of EDTA salt; and from 0.033 to 20 and preferably from 0.067 to 4 parts by weight of surfactant(s). Processes for cleaning aluminium apply the cleaning solutions by spraying at temperatures of 26 DEG to 66 DEG C and preferably from 32 DEG to 49 DEG C for periods of from 10 seconds to 2 minutes.

Description

SPECIFICATION Alkaline, aluminium-cleaning concentrates, solutions and processes This invention is concerned with cleaning the surfaces of articles made of aluminium -- a term used herein to encompass not only pure aluminium but also and especially alloys wherein aluminium is the predominant ingredient.

Containers made of aluminium (and especially aluminium alloys such as aluminium alloy 3004, defined hereinafter) are manufactured by a drawing-and-forming operation, commonly referred to as drawing-and-ironing, which results in the deposition upon the surfaces of the thusmanufactured container of lubricants and forming oils. Furthermore, residual aluminium fines (i.e.

fine particles of aluminium abraded or otherwise removed from the surface during the forming operation) are left on the surfaces of the container, with relatively larger quantities thereof on the inner surfaces.

The thus-manufactured containers must then be subjected to further processing, for example the formation of chemical-conversion coatings thereon and/or the appiication of sanitary lacquer coatings thereto -- but before such further processing can be performed the containersurfaces must be clean and waterbreak-free (that is to say, water upon the surface forms a continuous film which does not break up into droplets) in order to ensure that any contaminants which may still remain on the surface will not interfere with further processing of the containers.

Compositions and methods currently used commercially for cleaning aluminium containers are aqueous sulphuric acid solutions also containing hydrofluoric acid and one or more surfactants; and such cleaning solutions are quite effective, and have many advantages. Examples of such known, acidic aluminium-cleaning compositions are for instance those disclosed in Binns' United States Patents Nos. 4,009,115, 4,116,853 and 4,124,407, as well as King's United States Patent No. 3,969,135.There are however, some disadvantages associated with the use of such acidic cleaning compositions; they are for example capable of dissolving the iron-alloy, even stainless steel, equipment which is commonly utilized in the container-cleaning lines, while the disposal of any hydrofluoric acid and fluorides which may be present in spent cleaning baths and in used rinse-water gives rises to environment problems.

Attempts have already been made to avoid the problems of acid cleaning solutions by instead using alkaline or neutral solutions for cleaning aluminium. Examples of such known alkaline or neutral aluminium-cleaning compositions are for instance those disclosed in United States Patents Nos. 3,975,215, 3,888,783 and 4,093,566, and in Japanese Patent Specification Nos. Sho 53--149,130, 50-067,726,48-103,033 and 51-149,830. Attempts to use alkaline aluminium-cleaning solutions have however encountered serious new problems of their own, which militate against their commercial use.

When for instance alkaline cleaning solutions based upon alkali metal hydroxides were tried out, extensive and irregular etching of the aluminium containers was found to occur, rendering the containers commercially-unacceptable. Other kinds of alkaline solutions have also been tried out, but without success -- due to poor cleaning results and other problems.

We however have now discovered that it is possible to formulate alkaline cleaning solutions, which contain an alkali metal hydroxide and go far to overcome the kind of problems encountered with acidic cleaning solutions, yet which will bring about no more than an easily-controlled, uniform etching of any aluminium surfaces under treatment, regardless of the degree of hardness of the tap water used to make up these solutions.

According to one aspect of the present invention there is provided an aqueous cleaning solution, for removing and dissolving aluminium fines and for cleaning lubricating oils from aluminium surfaces, which comprises from about 0.5 to about 3 grams/litre of an alkali metal hydroxide, from about 1 to about 5 grams/litre of an alkali metal salt of ethylenediaminetetraacetic acid, and from about 0.1 to about 10 grams/litre of a surfactant.

These aqueous aluminium-cleaning solutions may be formulated quite inexpensively, with consequent economic advantages; and they may be used to clean aluminium surfaces so effectively that they are waterbreak-free and retain essentially no residual aluminium fines.

The alkali metal hydroxide is preferably sodium hydroxide or perhaps potassium hydroxide because although the other hydroxides can be used equally as well potassium hydroxide is more expensive than sodium hydroxide and lithium hydroxide still more so.

The alkali metal salt of ethylenediaminetetraacetic acid (EDTA) is also preferably a sodium salt, although again both potassium and lithium salts (and mixed salts) can also be employed. Although the mono-alkali metal salt can be used, it tends to be somewhat less soluble than the others in the concentrates of this invention to be described hereinafter, and consequently the EDTA salt used is preferably the ditri-, or tetra-alkali metal salt or a mixture of such salts.

The alkali metal hydroxide will preferably be present in a concentration within the range of from about 1 to about 2 grams/litre, and the alkali metal salt of ethylenediaminetetraacetic acid will preferably be present in a concentration within the range of from about 1.5 to about 3 grams/litre.

The surfactant(s) employed in the cleaning solution of this invention may be anionic, nonionic or cationic surfactants, or mixtures thereof subject only to the usual reservation that both cationic and anionic surfactants cannot be present simultaneously. We prefer to employ anionic and non-ionic surfactants, the especially preferred surfactant being an anionic one, as appears below.

There are of course a great many commerciallyavailable surfactants which can be used in the solutions of this invention, and specific examples thereof are for instance those disclosed in columns 6 and 7 of Binns' United States Patent No. 4,116,853. Merely for purposes of further illustration, it may be noted that below there is set out a list of some surfactants (and surfactant combinations) which we have found very serviceable, as follows:: (1) An anionic surfactant, believed to be composed of two parts of a modified polyoxyethylated straight-chain alcohol and one part of a linear alkyl succinate, sold under the tradename TRITON DF-20 by Rohm a Haas Company; (2) A combination of anionic surfactants, namely that identified at (1) above together with an alkali metal salt (preferably the sodium salt, though the potassium and/or lithium salts also may be used) of 2-butoxyethoxy acetic acid, for instance, sodium 2-butoxy-ethoxy acetate, sold under the tradename MIRAWET B by Miranol Chemical Company; (3) A non-ionic surfactant, believed to be a modified oxyethylated straight-chain alcohol, sold under the tradename PLURAFAC D-25 by BASF Wyandotte Corporation;; (4) A non-ionic surfactant, believed to be an ethoxylated abietic acid derivative with approximately 1 5 moles of ethoxylation, sold under the tradename SURFACTANT Art 50 by Hercules Inc.; (5) A combination of non-ionic surfactants, namely that identified at (4) above together with another non-ionic surfactant believed to be an alkyl polyethoxylated ether, sold under the tradename SURFONIC LF-17 by Jefferson Chemical Company:: (6) A non-ionic surfactant, believed to be a block copolymer of about 90% polyoxypropylene and about 10% polyoxyethylene sold under the tradename PLURONIC 31 Rl by BASF Wyandotte, Inc.; (7) A non-ionic surfactant, believed to be a modified polyethoxylated straight-chain alcohol, sold under the tradename TRITON DF-16 by Rohm a Haas Company; (8) A non-ionic surfactant, believed to be an alkylaryl polyether having a carbon chain of about 14 carbon atoms and approximately 1 6 moles of ethoxylation, sold under the tradename TRITON CF-10 by Rohm 8 Haas Company; (9) A non-ionic surfactant, believed to be a condensate containing only ethylene oxide and propylene oxide chains, sold under the tradename PLURONIC L061 by BASF Wyandotte, Inc.; and (10) A non-ionic surfactant, believed to be an alkly poly(ethyleneoxy)ethanol, sold under the tradename ANTAROX LF-330 by GAF Corporation.

The aluminium-cleaning solutions of this invention will preferably contain from about 0.2 to about 2.0 grams/litre of surfactant. When one of the above-described surfactant combinations is employed, it is preferred that the solution should contain from about 0.1 to about 1.0 grams/litre of each of the surfactants present therein.

The above-described preferred surfactants and surfactant combinations are in fact much preferred for use in the aluminium-cleaning solutions of this invention, because of their ability (particularly when an aluminium sequestering agent is also present, as will be described below) to prevent discoloration of any aluminium cans which are left standing wet with the cleaning solution during periods of line-stoppage. The most preferred surfactant for use in the present invention is TRITON DF-20, used either alone (1 above) or in combination (2 above) with an alkali metal salt of 2-butoxy-ethoxyacetate, above all because such surfactant or surfactant combination forms a very stable, homogeneous concentrate as will be described hereinafter.

Optionally but preferably the aluminiumcleaning solutions of this invention should also additionally contain from about 0.5 to about 10 grams/litre, and desirably from about 0.6 to about 1.3 grams/litre, of an aluminiumsequestering agent.

The aluminium-sequestering agent optionally included in the cleaning solutions of the invention can be any compound known for its ability to sequester aluminium in aqueous solution.

Examples of such compounds include sorbitol, an alkali metal (e.g. sodium) gluconate, an alkali metal (e.g. sodium) glucoheptonate, and an alkali metal (e.g. sodium) tartrate, with sorbitol and sodium glucoheptonate being preferred.

The alkaline aluminium-cleaning solutions of this invention may most conveniently be prepared from a concentrate containing the ingredients, which can be readily stored and shipped but which can, before use, be diluted with water to the required extent. Such concentrates, which form part of this invention, therefore contain the hereinspecified ingredients, in concentrated aqueous solution, each ingredient being present in the concentrate in absolute and relative amounts sufficient to establish the specified concentrations thereof in the cleaning solutions that result when the concentrate is diluted with a specified, controlled and appropriate quantity of water these absolute and relative amounts of the various ingredients in the concentrate being readily calculable from the information given herein.

According to another aspect of this invention there is therefore provided an aqueous concentrate, capable upon suitable dilution with water of forming a cleaning solution for removing and dissolving aluminium fines and for cleaning lubricating oils from aluminium surfaces, which concentrate comprises from about 25 to about 250 grams/litre of one or more alkali metal hydroxide(s) as well as, per part by weight of alkali metal hydroxide, from about 0.33 to about 10 parts by weight of one or more alkali metal salt(s) of ethylenediaminetetraacetic acid and from about 0.033 to about 20 parts by weight of one or more surfactant(s).

At least some of the concentrates of this invention are clear solutions, stable over a wide range of temperatures. They can be readily formulated, due to the high water solubility of their components; and they can be stored and shipped even under adverse ambient temperature conditions. It is an advantage of the concentrates of this invention that they can contain all of the ingredients needed to form the cleaning solution, unlike the acid-based concentrates where the inclusion of hydrofluoric acid in the concentrate is impractical, and where therefore the hydrofluoric acid component usually must be added separately under controlled, metered conditions, resulting in an extra step and expense in forming the cleaning solution.

As in the cleaning solutions themselves, it is preferred that in the concentrate the alkali metal hydroxide should be potassium and/or sodium hydroxide, and the alkali metal salt of ethylenediaminetetraacetic acid should be the disodium and/or the trisodium and/or the tetrasodium salt.

It is also preferred that in the concentrate, per part by weight of alkali metal hydroxide(s), the alkali metal salt(s) of ethylenediaminetetraacetic acid should be present in a ratio of from about 0.5 to about 6 parts by weight, and the surfactant(s) should be present in a ratio of from about 0.067 to about 4 parts by weight.

The surfactant(s) in the concentrates will of course be those chosen for incorporation in the cleaning solutions. As previously indicated, the most highly preferred surfactant for use in the concentrates of the invention is TRITON DF-20, used alone or in combination with an alkali metal 2-butoxyethoxyacetate, thus either (1) or (2) in the list previously given herein.This was the only surfactant or surfactant combination found to be freely soluble in the concentrates; all others tested separated out into a separate layer on top of the concentrate when the freshly-prepared concentrate was allowed to stand, which of course is a serious disadvantage for the other surfactants -- but is not fatal to their use in forming the cleaning solutions of the invention, because (a) the surfactants can if desired be omitted from the concentrate but added separately to form the cleaning solution or (b) the concentrate containing the separated surfactant can be thoroughly mixed by stirring or shaking just prior to its addition to water to form the cleaning solution, or (c) the layered concentrates can be packaged in containers small enough to permit addition of their entire contents when forming the cleaning solutions.

The surfactant (or surfactant combination) will preferably be present in the concentrate in a ratio, per part by weight of alkali metal hydroxide(s), of from about 0.067 to about 4 parts by weight.

The concentrate will also advantageously contain an aluminium-sequestering agent, in a ratio per part by weight of alkali metal hydroxide(s), of from about 0.17 to about 20 parts by weight, and preferably from about 0.20 to about 2.6 parts by weight.

As in the cleaning solutions themselves, the aluminium-sequestering agent in the concentrate will preferably be one or more of the following, namely sorbitol, alkali metal tartrate(s), alkali metal gluconate(s) and/or alkali metal glucoheptonate(s).

Using the above ratios as a guide, and depending upon the quantity of alkali metal hydroxide desired in the cleaning solutions of the invention, the actual quantities of alkali metal salt of ethylenediaminetetraacetic acid, surfactant, and aluminium sequestering agent in the concentrate are determined from within the above ratios so that the desired quantities of these ingredients are present in the cleaning solutions when the concentrate is diluted with an appropriate quantity of water.

For example, if 0.5 grams/litre of alkali metal hydroxide is desired in the cleaning solution, then from about 2 grams to about 10 grams of alkali metal salt of ethylenediaminetetraacetic acid, from about 0.2 grams to about 20 grams of surfactant, and optionally, from about 1.0 grams to about 20 grams of aluminium-sequestering agent should be present in the concentrate per gram of alkali metal hydroxide. If 3 grams/litre of alkali metal hydroxide is desired in the cleaning solution, then from about 0.33 grams to about 1.67 grams of alkali metal salt of ethylenediaminetetraacetic acid, from about 0.033 grams to about 3.33 grams of surfactant, and, optionally from about 0.17 grams to about 3.33 grams of aluminium-sequestering agent should be present in the concentrate per gram of alkali metal hydroxide.

According to a still further aspect of this invention, there is also provided a process for cleaning the surfaces of an article made of aluminium, which comprises the steps of (a) contacting said surface with the present aqueous cleaning solution at a temperature of at least about 800F (approximately 260 C) for a period sufficient to achieve the desired degree of cleaning, and thereafter (b) rinsing said cleaning solution from the aluminium surface.

The temperature of the cleaning solution should not normally exceed about 150"F (approximately 660C), and will preferably be maintained in the range of from about 900 to about 1200F (approximately 320--490C).

The period of contact with the cleaning solution will usually be in the range of from about 10 seconds to about 2 minutes, and preferably in the range of from about 30 seconds to about 1 minute.

The cleaning solution may be brought into contact with the aluminium surface by any appropriate method, for instance by spraying or by immersion.

Following the cleaning step, the aluminium surfaces must be rinsed with water to remove the cleaning solution. The aluminium surface may then be treated with coating solutions or siccative finish coating compositions well known to the art.

It may also here be noted that it may be desirable to prerinse the aluminium surfaces with water prior to the cleaning step, in order to reduce the amount of contaminants that would otherwise enter the cleaning bath.

The safe disposal of spent cleaning solutions and rinse waters should present few problems.

The alkali metal salts of ethylenediaminetetraacetic acid are for instance readily oxidized to environmentally-relatively harmless components by treatment of the spent cleaning solutions with small quantities of peroxides such as hydrogen peroxide; and to render the alkali metal hydroxide content harmless, it is readily possible to add water containing hydrochloric acid thereto until the pH of about 7 is obtained.

The process of this invention is especially useful when the aluminium article is an aluminium can; and the invention of course extends to aluminium cans and indeed other aluminium articles whenever their surfaces have been cleaned by the process herein disclosed.

In order that the invention may be well understood it will now be described in more detail, though only for purposes of illustration, in the following examples: EXAMPLES 1-6 Preparation of Concentrates A series of six concentrates was prepared by mixing together the ingredients listed below, in the indicated quantities, so as in each case to form one litre of concentrate.

Example 1 NaOH 50.00 g.

Na4EDTA* 100.00 g.

Sorbitol (70% soln.) 71.40 g.

MIRAWET B (49% aqueous solution) 23.00 g.

Water, sufficient to make 1 litre Example 2 NaOH 100.00 g.

Na4EDTA* 100.00 g.

MIRAWETB 47.4 g.

Water, sufficient to make 1 litre Example 3** NaOH 50.00 g.

Na3EDTA* 100.00 g.

Sorbitol (70% soln.) 71.40 g.

TRITON DF-16 23.00 g.

Water, sufficient to make 1 litre Example 4** KOH 150.00 g.

Na4EDTA* 300.00 g.

Sodium gluconate 175.00 g.

TRITON CF-20 125.00 g.

Water, sufficient to make 1 litre Example 5** LiOH 200.00 g.

Na4EDTA* 200.00g.

PLURONIC L061 200.00 g.

Water, sufficient to make 1 litre Example 6** NaOH 50.00 g.

Na4EDTA* 150.00 g.

Potassium tartrate 50.00 g.

Surfactant AR1 50 150.00 g.

ANTAROX LF-330 35.00 g.

Water, sufficient to make 1 litre Notes: * The abbreviation "EDTA" is used for ethylenediaminetetraacetic acid; so that for example, "Na4EDTA" means the tetrasodium salt of ethylenediaminetetraacetic acid.

** The concentrates of Examples 3, 4, 5 and 6 all exhibited layering on standing; and were therefore vigorously shaken or stirred before taking an aliquot portion to form the cleaning solutions of Examples 9-1 2 described subsequently herein.

EXAMPLE 7 Preparation of Cleaning Solution, and Treatment of Aluminium Cans therewith Stage A - Cleaning Solution 120 ml. of the concentrate of Example 1 was added to 5,880 litres of water (2% solution) thus to form six litres of a cleaning solution containing 1 g/l of NaOH. 2 g/l of Na,EDTA, 1.43 g/l of sorbitol (70% solution), and 0.46 g/l of MIRAWET B. This cleaning solution was stirred to render it uniform in composition.

Stage B -- Treatment of Aluminium Cans An aluminium can formed of aluminium 3004 alloy, drawn into single piece containers, was employed as the test specimen in this procedure.

The can was covered with aluminium fines and drawing oils. It may here be noted that aluminium alloy 3004 has the nominal composition 1.2% Mn, 1.0% Mg, balance Al and normal impurities.

The test specimen was treated as follows: (a) Sprayed with the above cleaning solution, maintained at 11 00F (approximately 430C) for one minute; (b) Rinsed with water, by immersion in cold water for 30 seconds; (c) Allowed to stand for 30 seconds, after which it was examined for water-breaks on both the inside and outside; and (d) The inside wiped with a clean white cloth, and the cloth examined for aluminium fines.

The respective examinations showed that the aluminium can was both free from water-breaks and free from aluminium fines.

EXAMPLE 8 Preparation of Cleaning Solution, and Treatment of Aluminium Cans therewith Stage A - Cleaning Solution 120 ml. of the concentrate of Example 2 was added to 5.880 litres of water, thus to form six litres of cleaning solution, otherwise containing the same quantities of ingredients per litre as in Example 7, but having twice the concentration, i.e.

2 g/l, of NaOH.

Stage B -- Treatment of Aluminium Cans The procedure of Example 7 was repeated, using an aluminium can formed by aluminium 3004 alloy and covered with aluminium fines and drawing oils, but maintaining the cleaning solution at a temperature of 900F (approximately 320C).

Examination of the can after treatment showed that it was free from water-breaks and from aluminium fines.

EXAMPLE 9 Preparation of Cleaning Solution, and Treatment of Aluminium Cans therewith Stage A - Cleaning Solution 1 20 ml. of the concentrate of Example 3 was added to 5.880 litres of water, thus to form six litres of a cleaning solution containing 1 g/l of NaOH, 2 g/l of Na3EDTA, 1.43 g/l of sorbitol (70% solution), and 0.46 g/l of TRITON DF-1 6. This cleaning solution was stirred to render it uniform in composition.

Stage B -- Treatment of Aluminium Cans An aluminium can, formed of aluminium 3004 alloy and covered with aluminium fines and drawing oils, was processed in the same manner as described in Example 7.

Examination of the can after treatment showed that it was free from water-breaks and from aluminium fines.

EXAMPLES 10-12 Preparation of Various Cleaning Solutions and Treatment of Aluminium Cans therewith Stage A - Cleaning Solutions 120 ml. of the concentrates of Examples 4, 5, and 6 were each added to 5.880 litres of water, to form six litres of cleaning solution (2% solutions).

Stage B -- Treatment of Aluminium Cans An aluminium can was treated with the respective cleaning- solutions resulting from Stage A, using the same procedure as in Example 7 except that the cleaning solutions prepared from the concentrates of Examples 4 and 5 were maintained at a temperature of 900F (approximately 320C).

Examination of the respective cans after treatment showed that all three of them were free from water-breaks and from aluminium fines.

EXAMPLE 13 Preparation of Concentrate, Preparation of Cleaning Solution therefrom, and Treatment of Aluminium Cans therewith Stage X -- Concentrate One litre of concentrate was prepared from the following ingredients: KOH 85.95 g.

Na4EDTA 100.00 g.

TRITON DF-20 30.60 g.

Beta Na glucoheptonate 32.50 g.

Water, sufficient to make 1 litre The concentrate was formed from these ingredients by first mixing together, in 500 ml. of water, 114 ml. of 50% KOH solution, 30.60 g. of TRITON DF-20, 50 ml. of a 50%-solution of beta sodium glucoheptonate sold under the tradename BELZAK BL-50 by The Belzak Corporation of Clifton, New Jersey, U.S.A.; and the Na4EDTA and the remainder of the necessary water were then added to the resulting mixture until a volume of one litre had been achieved. This mixture was then stirred; and the resultant concentrate was clear and homogeneous, having a cloud point of 1300 F (approximately 550C).

Stage Y - Cleaning Solution An aqueous cleaning solution was made by adding the above concentrate to water at a concentration of 2% by volume. The resulting cleaning solution had the following composition: KOH 1.72 g/l Na4EDTA 2.00 g/I TRITON DF-20 0.61 g/l Beta Na glucoheptonate 0.65 g/l Stage Z - Treatment of Aluminium Cans The aqueous cleaning solution was used to treat 10 aluminium cans, formed of aluminium 3004 alloy covered with aluminium fines and drawing oils.

The aluminium cans were treated as follows: (a) Sprayed with the above cleaning solution, maintained at a temperature of 11 00F (approximately 440 C), for a period of 30 seconds; (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 both the inside and outside; and (d) The inside wiped with a clean white cloth, and the cloth examined for aluminium fines.

Upon examination in this way, all of the aluminium cans were found to be free from waterbreaks and free from aluminium fines.

Stage Z' - Treatment of Aluminium Cans A further 10 cans were treated in an otherwise similar fashion as above, except that they were allowed to stand for 7.5 minutes after step (a), and were then examined. On this examination they appeared to be clean, and were without any sign of discoloration.

The cans were then further processed through steps (b) through (d) above; and all of them were found to be free from discoloration, free from water-breaks, and free from aluminium fines.

EXAMPLES 14-18 Preparation of Various Cleaning Solutions, and Treatment of Aluminium Cans therewith Stage A - Cleaning Solutions A series of cleaning solutions were formulated from the ingredients, in the indicated amounts, set out below: Example 14 NaOH i.00g/l Na4EDTA 2.00gel PLURAFAC D-25 0.61 g/I Beta Na glucoheptonate 0.65 g/l Example 1 5 NaOH 1.00 9/l.

Na4EDTA 2.00gel Surfactant AR 150 0.61 g/l Beta Na glucoheptonate 0.65 g/l.

Example 16 NaOH 1.00 9/l.

Na4EDTA 2.00 g/l PLURONIC31RI 0.61 g/l Beta Na glucoheptonate 0.65 g/l Example 17 NaOH l.00g/I Na4EDTA 2.00 g/l TRITON DF-20 0.61 g/l MIRAWET B 0.46 g/l Beta Na glucoheptonate 0.65 g/l Example 18 NaOH l.00g/l Na4EDTA 2.00 g/l Surfactant AR 1 50 0.61 g/l SURFONICLF17 0.61 9/1 Beta Na glucoheptonate 0.65 g/l Stage B -- Treatment of Aluminium Cans Each of the above aqueous cleaning solutions was used to treat a series of 10 aluminium cans, formed of aluminium 3004 alloy and covered with aluminium fines and drawing oils.The sequence of treatment of the aluminium cans was as follows: (a) Sprayed with the above cleaning solution, maintained at 1 00F (approximately 440C) for a period of 30 seconds; (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 both the inside and outside; and (d) The inside wiped with a clean white cloth, and the cloth examined for aluminium fines.

Upon such examination, all of the cans treated with each of the various cleaning solutions were found to be free from water-breaks and free from aluminium fines.

Stage B' - Treatment of Aluminium Cans A further series of 10 cans was treated with each of the same cleaning solutions; in exactly the same manner except that the cans were allowed to stand for 7.5 minutes after step (a), then examined. Upon this examination, all of the cans appeared to be clean, and all were without any sign of discoloration.

The cans were then further processed through steps (b) to (d) above; and upon re-examination, all of the cans treated with each of the cleaning solutions were found to be free from discoloration, free from water-breaks, and free from aluminium fines.

Claims (9)

1. An aqueous concentrate, capable upon dilution with water of forming a cleaning solution for removing and dissolving aluminium fines and for cleaning lubricating oils from aluminium surfaces, which concentrate comprises from about 25 to about 250 grams/litre of one or more alkali metal hydroxide(s) as well as, per part by weight of alkali metal hydroxide, from about 0.33 to about 10 parts by weight of one or more alkali metal salt(s) of ethylenediaminetetraacetic acid and from about 0.033 to about 20 parts by weight of one or more surfactant(s).

2. A concentrate as claimed in claim 1, in which the alkali metal hydroxide is potassium and/or sodium hydroxide, and the alkali metal salt of ethylenediaminetetraacetic acid is the disodium and/or the trisodium and/or the tetrasodium salt.

3. A concentrate as claimed in claim 1 or claim 2, in which per part by weight of alkali metal hydroxide(s) the alkali metal salt(s) of ethylenediaminetetraacetic acid is/are present in a ratio of from about 0.5 to about 6 parts by weight and the surfactant(s) is/are present in a ratio of from about 0.067 to about 4 parts by weight.

4. A concentrate as claimed in any of claims 1 to 3, in which per part by weight of alkali metal hydroxide(s) there is also present an aluminium sequestering agent in a ratio of from about 0.17 to about 20 parts by weight.

5. A concentrate as claimed in claim 4, in which the ratio of the aluminium sequestering agent is from about 0.20 to about 2.6 parts by weight.

6. A concentrate as claimed in claim 4 or claim 5, in which the aluminium sequestering agent is one or more of the following, namely sorbitol, alkali metal tartrate(s), alkali metal gluconate(s) and/or alkali metal glucoheptonate(s).

7. A concentrate as claimed in any of claims 1 to 6, in which the surfactant is one or more of the following: - (a) an anionic surfactant being composed of substantially two parts of a modified polyoxyethylated straight-chain alcohol and substantially one part of a linear alkyl succinate: - (b) a combination of anionic surfactants, namely that identified at (a) above together with an alkali metal salt of 2-butoxyethoxy acetic acid; - (c) a non-ionic surfactant being a modified oxyethylates straight-chain alcohol; - (d) a non-ionic surfactant being an ethoxylated abietic acid derivative with approximately 1 5 moles of ethoxylation; - (e) a combination of non-ionic detergents, namely that identified at (d) above together with an alkyl polyethoxylated ether; and - (f) a non-ionic surfactant being a block copolymer of about 90% polyoxypropylene and about 10% polyoxyethylene.

8. A concentrate as claimed in claim 7, in which the surfactant is one composed of substantially two parts of a modified polyoxyethylated straightchain alcohol and substantially one part of a linear alkyl succinate.

9. A concentrate as claimed in claim 7 or claim 8, in which the surfactant is present in a ratio of from about 0.067 to about 4 parts by weight thereof per part by weight of alkali metal hydroxide(s).

9. A concentrate as claimed in claim 7 or claim 8, in which the surfactant is present in a concentration within the range of from about 0.2 to about 2.0 g/l.

1 0. An aqueous concentrate as claimed in any of the preceding claims and substantially as herein described.

11. An aqueous concentrate, capable on dilution with water of forming a cleaning solution for removing and dissolving aluminium fines and for cleaning lubricating oils from aluminium surfaces, substantially as herein described with reference to any of the Examples.

12. An aqueous cleaning solution, for removing and dissolving aluminium fines and for cleaning lubricating oils from aluminium surfaces, which comprises from about 0.5 to about 3 grams/litre of an alkali metal hydroxide, from about 1 to about 5 grams/litre of an alkali metal salt of ethylene diaminetetraacetic acid, and from about 0.1 to about 10 grams/litre of a surfactant.

13. A solution as claimed in claim 12, which also contains from about 0.5 to about 10 grams/litre of an aluminium sequestering agent.

14. A solution as claimed in claim 13, in which the sequestering agent is present in a concentration of from about 0.6 to about

1.3 grams/litre.

1 5. A solution as claimed in claim 13 or claim 14, in which the sequestering agent is one or more of the following, namely sorbitol, alkali metal gluconate(s), alkali metal glucoheptonate(s) and/or alkali metal tartrate(s).

16. A solution as claimed in any of claims 12 to 15, in which the alkali metal hydroxide is present in a concentration within the range of from about 1 to about 2 grams/litre, and the alkali metal salt of ethylenediaminetetraacetic acid is present in a concentration within the range of from about 1.5 to about 3 grams/litre.

17. A solution as claimed in claim 16, in which the alkali metal hydroxide is potassium and/or sodium hydroxide, and the alkali metal salt of ethylenediaminetetraacetic acid is the disodium and/or the trisodium and/or the tetrasodium salt.

18. A solution as claimed in any of claims 12 to 17, in which the surfactant is one or more of the following: - (a) an anionic surfactant being composed of substantially two parts of a modified polyoxyethylated straight-chain alcohol and substantially one part of a linear alkyl succinate; - (b) an combination of anionic surfactants, namely that identified at (a) above together with an alkali metal salt of 2-butoxyethoxy acetic acid; - (c) a non-ionic surfactant being a modified oxyethylated straight-chain alcohol; - (d) a non-ionic surfactant being an ethoxylated abietic acid derivative with approximately 1 5 moles of ethoxylation; - (e) a combination of non-ionic detergents, namely that identified at (d) above together with an alkyl polyethoxylated ether; and - (f) a non-ionic surfactant being a block copolymer of about 90% polyoxypropylene and about 10% polyoxyethylene.

19. A solution as claimed in claim 18, in which the surfactant is one composed of substantially two parts of a modified polyoxyethylated straightchain alcohol and substantially one part of a linear alkyl succinate.

20. A solution as claimed in any of claims 12 to 19, in which the surfactant is present in a concentration within the range of from about 0.2 to about 2.0 g/l.

21. An aqueous cleaning solution as claimed in any of claims 12 to 20 and substantially as herein described.

22. An aqueous cleaning solution, for removing and dissolving aluminium fines and for cleaning lubricating oils from aluminium surfaces, substantially as herein described with reference to any of the Examples.

23. A process for cleaning the surfaces of an article made of aluminium, which comprises the steps of (a) contacting said surface with an aqueous cleaning solution as claimed in any of claims 12 to 22 at a temperature of at least about 800F (approximately 260C) for a period sufficient to achieve the desired degree of cleaning, and thereafter (b) rinsing said cleaning solution from the aluminium surface.

24. A process as claimed in claim 23, in which the temperature of the cleaning solution does not exceed about 150 F (approximately 660C).

25. A process as claimed in claim 23 or claim 24, in which the temperature of the cleaning solution is maintained in the range of from about 900 to about 1200F (approximately 320--490C).

26. A process as claimed in any of claims 23 to 25, in which the period of contact with the cleaning solution is in the range of from about 10 seconds to about 2 minutes.

27. A process as claimed in any of claims 23 to 26, in which the period of contact with the cleaning solution is in the range of from about 30 seconds to about 1 minute.

28. A process as claimed in any of claims 23 to 27, in which the aluminium article is an aluminium can.

29. A process for cleaning the surface of an article made of aluminium as claimed in any of claims 23 to 28 and substantially as herein described.

30. A process for cleaning the surfaces of an article made of aluminium substantially as herein described with reference to any of the Examples.

31. Aluminium articles whenever their surfaces have been cleaned by a process as claimed in any of claims 23 to 30.

New claims or amendments to claims filed on 1 5.10.82.

Superseded claims, Claim 9.

New or amended claims: