CA1170144A - Low temperature cleaner for metal surfaces - Google Patents
Low temperature cleaner for metal surfacesInfo
- Publication number
- CA1170144A CA1170144A CA000380699A CA380699A CA1170144A CA 1170144 A CA1170144 A CA 1170144A CA 000380699 A CA000380699 A CA 000380699A CA 380699 A CA380699 A CA 380699A CA 1170144 A CA1170144 A CA 1170144A
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- Prior art keywords
- cleaning
- inhibitor
- tin
- group
- quinones
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A process for cleaning soil, lubricants or other such contaminants from tin surfaces without visibly etching the tin surface by applying aqueous alkaline cleaning solutions to said surfaces, aqueous alkaline clean-ing solutions, and solid and aqueous concentrates from which the solutions may be formulated. The tin surface may be contacted with the solutions to substantially remove the contaminants therefrom by any conventional means known to the art. Spraying is a preferred means for contacting the surface with the solutions. The cleaning solutions may be effectively employed at temperatures as low as about 100°F and thus may be characterized as low temperature cleaners. The cleaning solutions comprise an alkaline component in an amount effective to substantially remove said contaminants from the tin surface and an inhibitor in an amount effective to inhibit or deter etch-ing of the tin surface. The inhibitor is-a compound selected from the group consisting of substituted benzenes having at least two or more hydroxy sub-stituents, quinones and substituted quinones.
A process for cleaning soil, lubricants or other such contaminants from tin surfaces without visibly etching the tin surface by applying aqueous alkaline cleaning solutions to said surfaces, aqueous alkaline clean-ing solutions, and solid and aqueous concentrates from which the solutions may be formulated. The tin surface may be contacted with the solutions to substantially remove the contaminants therefrom by any conventional means known to the art. Spraying is a preferred means for contacting the surface with the solutions. The cleaning solutions may be effectively employed at temperatures as low as about 100°F and thus may be characterized as low temperature cleaners. The cleaning solutions comprise an alkaline component in an amount effective to substantially remove said contaminants from the tin surface and an inhibitor in an amount effective to inhibit or deter etch-ing of the tin surface. The inhibitor is-a compound selected from the group consisting of substituted benzenes having at least two or more hydroxy sub-stituents, quinones and substituted quinones.
Description
- LO~ TEMPE:E~ATUI~: CLEA~ `R FOR M13TAL SUR~ACES
FIEI D OF THE INV~NTION
This invention relates to a composi-tion and a process for cleaning metal surfaces and more particularly relates to an aqueous alkaline cleaning solution containing a corrosion inhibitor which deters or inhibits etching of the ~etal sur~ace.
The invention will be described in connection with the cleaning of tin-plated surfaces, such as tin cans, which are soiled with organic lubricants that are applied to the tin surface as drawing aids during cold forming operations. qlhe invention has, never-theless, broader applicability.
Cleaning is essential as a preliminary to many surface finishing operations. It is normally required, for example, prior to corrosion preventive treatments and prior to the application of oxganic finishes to the surface, and is especially important in the case of metal surfaces to which organic materials have been recently applied as an aid to cold forming. These materials must be removed in order to obtain a surface suitably receptive to an organic or inorganill finish.
- One example of the need for such cleaning is in the manufacture of two-piece, tin-plated, drawn and ironed cans. C:Lrcular blanks of tin-plated steel, which, due to the high cost of tin, generally have only a thin layer of tin plating, are first cupped and then passed through several drawing dies to iron the cup in order to ~' , form a unitary side wall and can bottom slructure. A can produced by this process may be characterized as a thin-walled, thick-bottomed container having a generally uniform wall thickness, Such cans will be referred to herein as "DI"
(drawn and ironed) cans~ These forming operations are assis-ted and the dies and metallic surEace protected by the application of lubricants to the tin-plate surface prior to or during the forming operation. rrhe lubricants that are deposited on the tin surface usually consist of various types of mineral and vegetable oils and heavy metal soaps. Since it is desired to have a clean surface in order to assure adhesion of a subsequently applied sanitary lacquer and/or decorative varnish, the cleaning step after forming is critical to a successful manufacturing process.
A serious problem with DI tin-plated containers is that the drawing operation stretches the tin-plate surface, thereby exposing somé of the underlying meta~ which ex-posure may lead to corrosion. The underlying metal may be a ferrous metal, such as iron, iron alloys, and a wide variety of steels.
A problem with cleaners for tin-plate has been to obtain a cleaner that will provide a water-break-free surface without unduly etching the tin and without promoting corrosion of the underlying metal. A water-break-free surface is a surface that is sufficiently freed of ~ubricants, soil, and other contaminants so that it will maintain a continuous film of water.
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Etching results ~rom chemical attack of the cleaner on the tin surface and results in a rouyhened and dull surface. Furthermore, etching removes a portion of the corrosion protectlve tin from the surface, thereby de-grading the anti-corrosion qualities of the surface and aggravating the problem of corrosion due to exposure of the underlying metal. Where a smooth, shiny surface is desired, such as in the case of a beverage can, etching and/or corrosion is clearly undesirable.
Another problem with cleaners for tin-plate has been that they do not protect against conditions on the processing line where, after drawing and ironing and cleaning, line stoppage can expose the cleaned cans to the cleaner for prolonged periods of time. This prolonged exposure can lead to corrosion of the underlying surface exposed due to stretching or due to etching, thereby ren-dering the contalners unacceptable for use. Additionally, any corrosion and blemishes on the surface will adversely affect the adhesion of any conversion coating or sanitary lacquer coating that is applied thereafter.
Alkaline cleaners, such as aqueous solutions of alkali metal salts of silicates, phosphates, carbonates and borates, which have been found to be most suitable for producing the desired water-break-free surface, possess the undesirable tendency to etch the surface. It has pre-viously been discovered that the addition of certain com-pounds to the aqueous alkaline cleaning solutions will help to inhibit etching of the tin surface under the alkaline conditions employed, REPORTED DEVELOP~NTS
Inhibitors, such as the alkali metal salts of chromates, dichromates and, to a lesser extent, silicates, have previously been added to the aforementioned aqueous alkaline solutions to inhibit etching of the tin surface.
The resultant cleaners have generally been applied at temperatures in excess of 150F. Complete protection of the tin surface from etching is not always possible with such inhibitors, especially at a pH above about 12, since the attack of the alkaline compound on the tin surface tends to increase with increasing pH. Such cleaners having a pH below about 12 have less tendency to attack the tin surface and, hence, the well-known inhibitors are more effective, but the cleaning action of these lower pH
cleaners is usually slow, making it necessary to treat the tin surface for a prolonged period of time to effect cleaning. Additionally, when a chromium compound is used as the inhibitor, there are problems with toxicity and environmentally objectionable plant effluents.
A number of patents have been directed to com-positions and processes for cleaning tin surfaces. The cleaners disclosed in these patents are applied at tempera-tures of at least 140F and thus may be characterized as high temperature cleaners.
U.S. Patent No. 2,836,566 describes a cleaning composition for tin sur aces that, when added to water, comprises an aqueous solution of an alkaline metal meta-silicate; a water-soluble copper salt selected from the grollp consisting of sulfate, chloride, acetate and cyanidei an amine selected from the group consisting of '7~
-1,3-diamino butane, monoethanolamine, 2-amino-2-methyl l-propanol and triethanolamine; and soda ash. The solu-tions have a pH above about 11.8. One example dlscloses that the tin surface may be cleaned by immersion in the solution at boiling temperature within a 15-minute period.
The solution temperature and the cleanin~jtime are economically disadvantageous due to the energy require-ments for maintaining a cleaning solution at boiling tem-perature concurrent with the requirement that the object to be cleaned be immersed for about 15 minutes. Additionally, the requirement of a copper salt, including copper cyanide, presents waste disposal and toxicity problems tha-t add to the cost of the cleaning process employing these solutions and makes them undesirable for use on beverage cans and the like. Furthermore, it is possible that when using a solu-tion containing a copper salt, some copper will be plated on tne tin surface. This is objectionable since the copper may be visible and a uniform shiny tin surface is generally preferred by, for example, manufacturers who purchase cans to be filled with beverages.
U. S. Patent No. 3,8~8,783 discloses a cleaning composition that, when added to water, forms an aqueous solution for cleaning tin-plated ferrous metal surfaces.
Tne aqueous solution contains an alkali metal metasilicate, a condensed phosphate selected from the group consisting of tripolyphosphate and pyrophosphate, and borax. The alkali metal metasilicate is said to increase the detergency of the solution and to provide added protection of the surface from corrosion prior to conversiGn coating.
The cleaning solutions are applied to the surface for fifteen seconds to about one minute at temperatures of from about 150 to 190F. The preferred temperatures is from about 150 to 170F. The pH is maintained at a level within the range of from about 9.0 to about 10.15. A11 of the examples disclose solutions having a pH less ~han 10 and a temperature of at least 160F.
The solutions do possess certaln disadvantages.
The primary disadvantage is that the solutions must be applied at temperatures in excess of 150F and thus re-quire a greater energy expenditure and therefore cost more to use than would a significantly lower-temperature cleaner.
Furthermore, both borates and phosphates may present environ-mental problems and, hence, may present plant effluent treatment problems.
U. S. Patent No. 4,094,701 discloses a process for cleaning a tin surface without substantially etching the tin. The process comprises contacting the surface with an aqueous alkaline solution containing an alkaline compo-nent which may be an al~ali metal borate, carbonate, phos-phate, hydroxide, oxide, silicate, or mixtures thereof;
one or more surfactants; and, as an inhibitor, an organic tannin. The object to be cleaned is sprayed with the solution at elevated temperature for about one to about two minutes. The pH of the cleaner is at least 9, preferably between 10 and 13, and most preferably between 10 and 10.5.
Higher pH values tend to gradually inactivate the tannin.
The patent teaches that temperatures of 140F and upwards will normally be employed when the cleaner is adjusted to the preferred pH range. Thus, the patent teaches employing ~ ~7(~
.
.
the cleaner disclosed therein a-t temperatures in excess of 140F and at pH values between 9 and 10.5.
The patent discloses i:hat alkali metal ~orates and phosphates may be used. Both borates and phosphates may present en~ironmental problems and, hence, may present plant effluent treatment problems. While the patent dis-closes a cleaning solution that may be used for cleaning tin surfaces, without etching, at -temperatures below boiling and for periods of time less than two minutes, the use of temperatures in excess of 140F is still economically disadvantageous.
Thus, there still exists the need for a compo-sition that may be used effectively on tin surfaces to produce water-break-free surfaces without etching the tin at lower temperatures than previously, effectively employed when applied for periods of about one minute or less and for periods of time longer th~ have previously been dis-closed for use without etching in order to realize a sig-nificant cost savings, reduce the possiblity of etching and corrosion during line stoppàge, and minimize the ex-penditure of energy, without the use of components presently known to be environmentally objectionable.
OBJECTS O~ T~lE INVENTION
It is, therefore, an object of the present invention to provide compositions, solutions, and a process for cleaning tin surfaces and,particularly, tin-plated metal surfaces, so that they are water-break-free without etching the tin and to do so at lower temperatures than have heretofore effectively been employed, and without the use of components presently known to be environmentally objectionable.
I
, It is a particular object of the present invent.ion to provide a low -temperature aqueous alkaline solu-tion for cleaning tin-plated me-tal surfaces so -tha-t they are wa-ter-break~free without etching of the -t:in.
It is a fur-ther objec-t of -the present invention -to provide cleaning compositions and a process for -their use for cleaning tin-plated metal surfaces at low temperatures -to produce a water-break-free surface without e-tching the tin.
SU~MARY OF THE INVENTION
In accordance wi-th one aspect of this invention, there is provided a process for cleaning tin surfaces to subs-tantially remove soil, lubricants or other con-taminants therefrom without visibly etching the tin surface by applying to said tin surface an aqueous alkaline cleaning solu-tion having a pH of about 11 -to about 13 and comprising an alkaline component in an amount effective to substantially remove said contaminants from the tin surface and an inhibitor, in an amoun-t effective to inhibi-t etching of the surface, selected from the group consisting of substituted benzenes having at least two hydroxy .substituents, quinones and substituted quinones.
In accordance with ano-ther aspect of this invention, there is provided an aqueous cleaning solution having a pH of about 11 to about 13 for cleaning -tin surfaces to subs-tantially remove soil, lubricants or other contaminan-ts therefrom without visibly etching the tin surface, at temperatures between about 100F -to about 130F, and comprising an alkaline component, in an amount effective to substantially remove from the tin surface contaminants thereon, and an inhibitor, in an amount effective to inhibit e-tching of the surface, selected from the ~roup consisting of quinones, substituted quinones, and substituted benzenes having at least two or more hydroxy substituents in the ortho, para, meta, symmetric or assymmetric ~.,.,,~ 1 ~ ~7~
configura-tions.
DETAILED DESCRIPTION OF THE INVENTION
. . _ The alkaline component in the cleaning solu-tion useful in the process and composition of this invention may be any of the compounds known to - 8a -.~17()~
the art that produces an alkaline solution when dissolved in water. Prefer-ably the alkaline component is applied in the form of a compound selected from the group consisting of alkali metal hydroxides, carbonates and sili-cates, ammonium hydroxides and carbonates, and mixtures thereof. Particul-arly preferred as the alkaline component is a mixture of sodium carbonate, sodium metasilicate and a compound selected from the group consisting of sodium hydroxide and potassium hydroxide.
The alkaline component is present in the cleaning solution in an amount effective to substantially remove soil, lubricants or other such COTI-taminants. Generally, more of the alkaline component will be required whenthe solution is applied at higher temperatures and less will be required when the solution is applied at lower temperatures. Preferably, the amount of alkaline component in the solution will be at least about 2 g/l, and more preferably will be about 3 g/l to about 5 g/l. Greater concentrations may be employed but the benefit to be gained thereby is generally not signifi-cant.
The cleaning solution will generally have a pH value within the range of abou~ 11 to about 13 and may preferably have a pll value within the range of about 12 to about 12.8. The pH is determined at a solution tempera-ture of about 27C.
The inhibitor of the cleaning solution useful in the process ofthis invention is a compound selected from the group consisting of sub-stituted benzenes having at leas* two or more hydroxy substituents, quinones, and substituted quinones. A mixture of inhibitors can also be used.
Exemplary substituents in the benzene ring include, in addition to hydroxy, halo, alkyl, carboxy, nitro, cyano and alkoxy. Such substituents are also exemplary of substituents of the substituted quinone.
Exemplary quinones and substituted quinones useful as inhibitors in the practice of this invention include 1,2-benzoquinone and 1,4-benzo-quinone and the substituted quinones according to Formulae II and III.
1 ~ 3 ~ ormula II
1~
Rl J~o ll I Pormula III
R
wherein:
Rl, R2, R3 and R~ are hydrogen, alkyl, alkoxy, hydroxy7 halo, nitro,cyano, or carboxyl; or Rl and R2 form an alkyldienyl group and, together with the qui~one ring to which they are attached, form a napthaquinone.
Exemplary substituted benzene inhibitors, of particular interest in the composition of this invention, include polyhydroxybenzenes, such as~
catechol, resorcinol, 1,4-dihydroquinone, 1,2,~-trihydroxybenzene, 1,3,5-trihydroxybenzene and l,2,4,5-tetrahydroxybenzene.
Preferred inhibitors for use in the process of this invention in-clude 3,~,5-trihydroxybenzoic acid7 1,2,3-benzene triol and dihydroxy-benzenes and quinones, such as~ 1,4-benzenediol and l,~-benzoquinone.
The inhibitor is added in an amount effective to inhibit etching of the surface. Generally, as the concentration of the alkaline component increases, the concentration of the inhibitor required will also increase.
Also, as will be discussed below,~since "soft" water tends to ba more corro-sive than "hard'l water, a greater concentration of inhibitor will generally be required when the cleaning solutions are formulated using soft water than will be required when formulated with hard waterO Preferably, the amount of inhibitor in the solution will be at least about 0.02 g/l, and more prefer-ably will be about 0.02 g/l to about 0.0~ g/l. Concentrations greater than ~ t7(~
0.06 g/l may be effectively employed but the resultant increase in cost is not generally offset by a greater inhibition of etching.
It has been discovered that the addition of a poly~
electrolyte to tile cleaning solu~ions of the invention provides a solution that may be effectively employed regardless of the hard-ness of the water used to formulate the solution without generally experiencing precipitation of the calcium and magnesium ions that cause water hardness. Such precipitation is a problem since it may result in sediment that may, for example, clog spray nozzles when spraying is the chosen method of application.
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Polyelectrolytes are high molecular weight electrolytes of either natural orlgin, such as proteins, or of a synthetic nature, such as polymerized organic acids. Since the polyelectrolytes in solution do not dissociate to give a uniform distribution of positive and negative ions, as do simple electrolytes, the ions of one sign are bound to the polymer chain. Thus, Eor instance, the negative charges may be in the polymer chain, and only positive ions will be free to diffuse through the solvent.
Hardness is a characteristic of water generally accepted to represent the total concentration of calcium and magnesium ions. Other polyvalent cations that are seldom present in more than trace amounts may also contribute to hardness. Determination of hardness may be made by titration as set forth in "Standard Methods of Test for Hardness in Water", Designation D 1126-67 (Reapproved 1974) published by the American Society for Testing and Materials. Hardness may be given in parts per million (ppm) of calcium carbonate e ~ valent. The higher the value, the greater the hardness. Water hardness may vary greatly from one plant site to another.
Generally, water havlng a hardness of less than about 100 ppm may be considered "soft" whereas water having a hardness above about 100 ppm may be considered "hard".
In scme coastal regions the hardness may be only about 50 ppm to about 100 ppm and may increase to about 300 ppm where the water runs at some point through limestone deposits. In some areas of the midwest, the hardness may be about 400 ppm to about 500 ppm. Precipitation ~ 3~ ~ ~
will generally be experienced to a greateT extent as the hardness of the water increases. As hardness decreases, the water may tend to become more corrosive. Therefore, a polyelectrolyte is prefer-ably, but optionally added to the cleaning solutions of the pre-sent invention.
Tlle polyelectrolyte, when aclded, may be any of the com-po~mds known to the art to prevent precipitation o-f the minerals that cause water hardne$s. If a polyelectrolyte is selected that does not contain phosphate, certain advantages may be realized.
An important advantage is that the plant effluent will not contain phosphates since phosphates may be considered environmentally objectionable. Additionally, the allcali metal tripolyphosphates, which have previously been employed, may have the deleterious effect of promoting etching or detinning. Thus, polyelectrolytes preferred for use in the cleaning solutions of the present inven-tion are polyelectrolytes such as Gantrez, S-95*, manufactured by GAF Corporation, and Tamol 960*, manufactured by Rohm and Haas Company. These polymers do not promote detinning and may inhibit etching to some extent.
Ihe polyelectrolyte, when added, is preferably added in an amount effective to substantially prevent precipitation of the calcium and magnesium ions that are the primary cause of water hardness. Generally, greater amounts of polyelectrolyte will be required when the hardness of the water is high than when the hardness of the water is low. Preferably, the amount of poly-electrolyte will be at least about 0.1 g/1 and more preferably from about 0.1 g/1 to about 1 g/1. Concentrations *Trade Mark 7v~ L F
in excess of l g/1 may be present in the cleaning solutions but, generally, higher concentrations will not result in a significant improvement in the desired effect.
It is preferred but not essential to add one or more surfactants to the aqueous alkaline cleaning~solutions of the present invention. Additionally, when a surfactant is added that is not a low foaming surEactant/ a defoaming agent is desirably added~ A defoamer is desirable in such a case since foaming can present a serious problem to a commercial operation in that it may delay or shut down the cleaning line. Such materials enhance the performance of the cleaning solution but are not the essence of the invention since they are used to perform functions essentially similar to the function they perform in prior art solutions. The presence or absence of surfactants has been found to have no noticeable effect as far as inhibiting or promoting the etching of a tin surface by the cleaning solution.
:
Exemplary of the surfactants and wetting agents that can be employed in the cleaning solutions are ethoxy-lated straight chained alcohols and octyl or nonyl phenoxy polyethoxyethanol. Generally, nonionic surfactants are pre-ferred since they are low foaming~
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When s~rfactants are added, it is preferred that the cleaning solutions contain at least about 0.2 g/1 of one or more surfactants. A particularly preferred amount is from about 0.2 9/1 to about 0.5 g/l.
Tin surfaces may be c]eaned by contacting the sur-face with the aqueous alkaline c:leaning solutions of the present invention for a time and at a temperature effective to remove soil, lubricants or other such surface contaminants therefrom without visibly etching the tin surface. Generally, the solution temperature will be at least about 100F. A
preferred range is from about 100~ to about 130F, and more preferably from about 115F to about 125F. The temperature employed may tend to be higher for solutions having low concentrations of alkaline components than for solutions having higher concentrations of alkaline components. Thus, the treatment temperature may tend to vary somewhat inversely with the pH of the cleaning solution.
The time of treatment will generally depend on the method of application. A preferred method of appli-cation is spraying and when this method is used the treat-ment time will tend to decrease as the spraying pressure increases. ~eans for spraying as presently known in the art generally operate at spraying pressures of about 25 psi to about 35 psi and treatment times of about 40 seconds to about one minute may be sufficient to produce a water-break-free surface. I~eans for spraying at pressures of .~ a ~
60 psi to 100 psi are known but no-t generally used at present and may employ effective tre.atment times of about 1 to 5 seconds. Spraying is merely exemplary of the methods of application. Any conventional means known to the art may be used to contact the tin-plated surface with the cleaning solution.
The treatment time will also tend to increase the longer the interval between manufacture of the tin-plated metal article and the cleaning thereof. With drawn and ironed tin-plated steel cans, an interval of as little as fifteen minutes may noticeably result in an increased cleaning time. Additionally, the treatment time may vary depending on the type of lubricant used in the manufacturing process; some lubricants being more readily removed than others.
Application times of up to about 30 minu~es have been employed for purposes of determining the extent to which the present cleaning solutions will inhibit etching of the tin and it has been determined that a tin-plated surface may be contacted with the present solutions for up to about 30 minutes without etching the tin. In actual practice, however, it is contemplated that the shortest time effec-tive to produce a water-break-free surface without etching the tin will be employed in applying the present compositions to the tin surface to be cleaned in order to realize the greatest cost efficiency. After the tin surface is treated with the cleaning composition, the surface will generally be rinsed at least once with tap water and then may be rinsed with deionized water and dried at elevated temperature, preferably from about 350 to about 400F.
Thus, surprisingly, the present compositions, when formulated as an aqueous alkaline cleaning solution and contacted with a tin-plated me-tal surface for a period as long as about 30 minutes, will not visi~ly etch the tin. The present solutions, therefore, provide signifi-cantly increased protection against etching and corrosion over the prior art solutions in the event of line stoppage or similar such prolonged exposures to the cleaning solu-tions. Additionally, whereas the prior art solutions have required temperatures in excess of 140F in order to effectively clean the tin surface to produce a water-break-free surface withoutvisibly etching the tin, the present cleaning solutions may be effectively employed at tempera~
tures as low as at least about 100F and may preferably be employed at temperatures of from about 100F to about 130F. Thus, significant savings in energy costs may be realized using the solutions of the present invention, which solutions may be effectively applied at temperatures as much as 40 degrees less than those of the prior art solutions to produce water-break-free tin-plated surfaces that are not visibly etched.
The cleaner of the present invention may be formulated as an aqueous concentrate or as a solid cleaning composition to be added to water to produce the aqueous alkaline cleaning solutions of the present invention.
As an aqueous concentrate the cleaner is formu-lated such that when the aqueous concentrate is added to water at a concentration of about 0.5% to about 2% by volume it produces an aqueous alkaline cleaning solution having a pH of about 11 to about 13 for cleaning tin surfaces to substantia:Lly remove soil, lubricants or other contaminants -16~
therefrom without visibly etching the tin surface, even at low solution temperatures, and comprises an alkaline component in an amount effective to substantially remove said contaminants from the tin surface, and an inhibitor ln an amount effective to inhibit etching of the surface. The inhibitor is a compound as defined above. The concentrate may preferably be added to water at a concentration of about 1~ to about
FIEI D OF THE INV~NTION
This invention relates to a composi-tion and a process for cleaning metal surfaces and more particularly relates to an aqueous alkaline cleaning solution containing a corrosion inhibitor which deters or inhibits etching of the ~etal sur~ace.
The invention will be described in connection with the cleaning of tin-plated surfaces, such as tin cans, which are soiled with organic lubricants that are applied to the tin surface as drawing aids during cold forming operations. qlhe invention has, never-theless, broader applicability.
Cleaning is essential as a preliminary to many surface finishing operations. It is normally required, for example, prior to corrosion preventive treatments and prior to the application of oxganic finishes to the surface, and is especially important in the case of metal surfaces to which organic materials have been recently applied as an aid to cold forming. These materials must be removed in order to obtain a surface suitably receptive to an organic or inorganill finish.
- One example of the need for such cleaning is in the manufacture of two-piece, tin-plated, drawn and ironed cans. C:Lrcular blanks of tin-plated steel, which, due to the high cost of tin, generally have only a thin layer of tin plating, are first cupped and then passed through several drawing dies to iron the cup in order to ~' , form a unitary side wall and can bottom slructure. A can produced by this process may be characterized as a thin-walled, thick-bottomed container having a generally uniform wall thickness, Such cans will be referred to herein as "DI"
(drawn and ironed) cans~ These forming operations are assis-ted and the dies and metallic surEace protected by the application of lubricants to the tin-plate surface prior to or during the forming operation. rrhe lubricants that are deposited on the tin surface usually consist of various types of mineral and vegetable oils and heavy metal soaps. Since it is desired to have a clean surface in order to assure adhesion of a subsequently applied sanitary lacquer and/or decorative varnish, the cleaning step after forming is critical to a successful manufacturing process.
A serious problem with DI tin-plated containers is that the drawing operation stretches the tin-plate surface, thereby exposing somé of the underlying meta~ which ex-posure may lead to corrosion. The underlying metal may be a ferrous metal, such as iron, iron alloys, and a wide variety of steels.
A problem with cleaners for tin-plate has been to obtain a cleaner that will provide a water-break-free surface without unduly etching the tin and without promoting corrosion of the underlying metal. A water-break-free surface is a surface that is sufficiently freed of ~ubricants, soil, and other contaminants so that it will maintain a continuous film of water.
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Etching results ~rom chemical attack of the cleaner on the tin surface and results in a rouyhened and dull surface. Furthermore, etching removes a portion of the corrosion protectlve tin from the surface, thereby de-grading the anti-corrosion qualities of the surface and aggravating the problem of corrosion due to exposure of the underlying metal. Where a smooth, shiny surface is desired, such as in the case of a beverage can, etching and/or corrosion is clearly undesirable.
Another problem with cleaners for tin-plate has been that they do not protect against conditions on the processing line where, after drawing and ironing and cleaning, line stoppage can expose the cleaned cans to the cleaner for prolonged periods of time. This prolonged exposure can lead to corrosion of the underlying surface exposed due to stretching or due to etching, thereby ren-dering the contalners unacceptable for use. Additionally, any corrosion and blemishes on the surface will adversely affect the adhesion of any conversion coating or sanitary lacquer coating that is applied thereafter.
Alkaline cleaners, such as aqueous solutions of alkali metal salts of silicates, phosphates, carbonates and borates, which have been found to be most suitable for producing the desired water-break-free surface, possess the undesirable tendency to etch the surface. It has pre-viously been discovered that the addition of certain com-pounds to the aqueous alkaline cleaning solutions will help to inhibit etching of the tin surface under the alkaline conditions employed, REPORTED DEVELOP~NTS
Inhibitors, such as the alkali metal salts of chromates, dichromates and, to a lesser extent, silicates, have previously been added to the aforementioned aqueous alkaline solutions to inhibit etching of the tin surface.
The resultant cleaners have generally been applied at temperatures in excess of 150F. Complete protection of the tin surface from etching is not always possible with such inhibitors, especially at a pH above about 12, since the attack of the alkaline compound on the tin surface tends to increase with increasing pH. Such cleaners having a pH below about 12 have less tendency to attack the tin surface and, hence, the well-known inhibitors are more effective, but the cleaning action of these lower pH
cleaners is usually slow, making it necessary to treat the tin surface for a prolonged period of time to effect cleaning. Additionally, when a chromium compound is used as the inhibitor, there are problems with toxicity and environmentally objectionable plant effluents.
A number of patents have been directed to com-positions and processes for cleaning tin surfaces. The cleaners disclosed in these patents are applied at tempera-tures of at least 140F and thus may be characterized as high temperature cleaners.
U.S. Patent No. 2,836,566 describes a cleaning composition for tin sur aces that, when added to water, comprises an aqueous solution of an alkaline metal meta-silicate; a water-soluble copper salt selected from the grollp consisting of sulfate, chloride, acetate and cyanidei an amine selected from the group consisting of '7~
-1,3-diamino butane, monoethanolamine, 2-amino-2-methyl l-propanol and triethanolamine; and soda ash. The solu-tions have a pH above about 11.8. One example dlscloses that the tin surface may be cleaned by immersion in the solution at boiling temperature within a 15-minute period.
The solution temperature and the cleanin~jtime are economically disadvantageous due to the energy require-ments for maintaining a cleaning solution at boiling tem-perature concurrent with the requirement that the object to be cleaned be immersed for about 15 minutes. Additionally, the requirement of a copper salt, including copper cyanide, presents waste disposal and toxicity problems tha-t add to the cost of the cleaning process employing these solutions and makes them undesirable for use on beverage cans and the like. Furthermore, it is possible that when using a solu-tion containing a copper salt, some copper will be plated on tne tin surface. This is objectionable since the copper may be visible and a uniform shiny tin surface is generally preferred by, for example, manufacturers who purchase cans to be filled with beverages.
U. S. Patent No. 3,8~8,783 discloses a cleaning composition that, when added to water, forms an aqueous solution for cleaning tin-plated ferrous metal surfaces.
Tne aqueous solution contains an alkali metal metasilicate, a condensed phosphate selected from the group consisting of tripolyphosphate and pyrophosphate, and borax. The alkali metal metasilicate is said to increase the detergency of the solution and to provide added protection of the surface from corrosion prior to conversiGn coating.
The cleaning solutions are applied to the surface for fifteen seconds to about one minute at temperatures of from about 150 to 190F. The preferred temperatures is from about 150 to 170F. The pH is maintained at a level within the range of from about 9.0 to about 10.15. A11 of the examples disclose solutions having a pH less ~han 10 and a temperature of at least 160F.
The solutions do possess certaln disadvantages.
The primary disadvantage is that the solutions must be applied at temperatures in excess of 150F and thus re-quire a greater energy expenditure and therefore cost more to use than would a significantly lower-temperature cleaner.
Furthermore, both borates and phosphates may present environ-mental problems and, hence, may present plant effluent treatment problems.
U. S. Patent No. 4,094,701 discloses a process for cleaning a tin surface without substantially etching the tin. The process comprises contacting the surface with an aqueous alkaline solution containing an alkaline compo-nent which may be an al~ali metal borate, carbonate, phos-phate, hydroxide, oxide, silicate, or mixtures thereof;
one or more surfactants; and, as an inhibitor, an organic tannin. The object to be cleaned is sprayed with the solution at elevated temperature for about one to about two minutes. The pH of the cleaner is at least 9, preferably between 10 and 13, and most preferably between 10 and 10.5.
Higher pH values tend to gradually inactivate the tannin.
The patent teaches that temperatures of 140F and upwards will normally be employed when the cleaner is adjusted to the preferred pH range. Thus, the patent teaches employing ~ ~7(~
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.
the cleaner disclosed therein a-t temperatures in excess of 140F and at pH values between 9 and 10.5.
The patent discloses i:hat alkali metal ~orates and phosphates may be used. Both borates and phosphates may present en~ironmental problems and, hence, may present plant effluent treatment problems. While the patent dis-closes a cleaning solution that may be used for cleaning tin surfaces, without etching, at -temperatures below boiling and for periods of time less than two minutes, the use of temperatures in excess of 140F is still economically disadvantageous.
Thus, there still exists the need for a compo-sition that may be used effectively on tin surfaces to produce water-break-free surfaces without etching the tin at lower temperatures than previously, effectively employed when applied for periods of about one minute or less and for periods of time longer th~ have previously been dis-closed for use without etching in order to realize a sig-nificant cost savings, reduce the possiblity of etching and corrosion during line stoppàge, and minimize the ex-penditure of energy, without the use of components presently known to be environmentally objectionable.
OBJECTS O~ T~lE INVENTION
It is, therefore, an object of the present invention to provide compositions, solutions, and a process for cleaning tin surfaces and,particularly, tin-plated metal surfaces, so that they are water-break-free without etching the tin and to do so at lower temperatures than have heretofore effectively been employed, and without the use of components presently known to be environmentally objectionable.
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, It is a particular object of the present invent.ion to provide a low -temperature aqueous alkaline solu-tion for cleaning tin-plated me-tal surfaces so -tha-t they are wa-ter-break~free without etching of the -t:in.
It is a fur-ther objec-t of -the present invention -to provide cleaning compositions and a process for -their use for cleaning tin-plated metal surfaces at low temperatures -to produce a water-break-free surface without e-tching the tin.
SU~MARY OF THE INVENTION
In accordance wi-th one aspect of this invention, there is provided a process for cleaning tin surfaces to subs-tantially remove soil, lubricants or other con-taminants therefrom without visibly etching the tin surface by applying to said tin surface an aqueous alkaline cleaning solu-tion having a pH of about 11 -to about 13 and comprising an alkaline component in an amount effective to substantially remove said contaminants from the tin surface and an inhibitor, in an amoun-t effective to inhibi-t etching of the surface, selected from the group consisting of substituted benzenes having at least two hydroxy .substituents, quinones and substituted quinones.
In accordance with ano-ther aspect of this invention, there is provided an aqueous cleaning solution having a pH of about 11 to about 13 for cleaning -tin surfaces to subs-tantially remove soil, lubricants or other contaminan-ts therefrom without visibly etching the tin surface, at temperatures between about 100F -to about 130F, and comprising an alkaline component, in an amount effective to substantially remove from the tin surface contaminants thereon, and an inhibitor, in an amount effective to inhibit e-tching of the surface, selected from the ~roup consisting of quinones, substituted quinones, and substituted benzenes having at least two or more hydroxy substituents in the ortho, para, meta, symmetric or assymmetric ~.,.,,~ 1 ~ ~7~
configura-tions.
DETAILED DESCRIPTION OF THE INVENTION
. . _ The alkaline component in the cleaning solu-tion useful in the process and composition of this invention may be any of the compounds known to - 8a -.~17()~
the art that produces an alkaline solution when dissolved in water. Prefer-ably the alkaline component is applied in the form of a compound selected from the group consisting of alkali metal hydroxides, carbonates and sili-cates, ammonium hydroxides and carbonates, and mixtures thereof. Particul-arly preferred as the alkaline component is a mixture of sodium carbonate, sodium metasilicate and a compound selected from the group consisting of sodium hydroxide and potassium hydroxide.
The alkaline component is present in the cleaning solution in an amount effective to substantially remove soil, lubricants or other such COTI-taminants. Generally, more of the alkaline component will be required whenthe solution is applied at higher temperatures and less will be required when the solution is applied at lower temperatures. Preferably, the amount of alkaline component in the solution will be at least about 2 g/l, and more preferably will be about 3 g/l to about 5 g/l. Greater concentrations may be employed but the benefit to be gained thereby is generally not signifi-cant.
The cleaning solution will generally have a pH value within the range of abou~ 11 to about 13 and may preferably have a pll value within the range of about 12 to about 12.8. The pH is determined at a solution tempera-ture of about 27C.
The inhibitor of the cleaning solution useful in the process ofthis invention is a compound selected from the group consisting of sub-stituted benzenes having at leas* two or more hydroxy substituents, quinones, and substituted quinones. A mixture of inhibitors can also be used.
Exemplary substituents in the benzene ring include, in addition to hydroxy, halo, alkyl, carboxy, nitro, cyano and alkoxy. Such substituents are also exemplary of substituents of the substituted quinone.
Exemplary quinones and substituted quinones useful as inhibitors in the practice of this invention include 1,2-benzoquinone and 1,4-benzo-quinone and the substituted quinones according to Formulae II and III.
1 ~ 3 ~ ormula II
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Rl J~o ll I Pormula III
R
wherein:
Rl, R2, R3 and R~ are hydrogen, alkyl, alkoxy, hydroxy7 halo, nitro,cyano, or carboxyl; or Rl and R2 form an alkyldienyl group and, together with the qui~one ring to which they are attached, form a napthaquinone.
Exemplary substituted benzene inhibitors, of particular interest in the composition of this invention, include polyhydroxybenzenes, such as~
catechol, resorcinol, 1,4-dihydroquinone, 1,2,~-trihydroxybenzene, 1,3,5-trihydroxybenzene and l,2,4,5-tetrahydroxybenzene.
Preferred inhibitors for use in the process of this invention in-clude 3,~,5-trihydroxybenzoic acid7 1,2,3-benzene triol and dihydroxy-benzenes and quinones, such as~ 1,4-benzenediol and l,~-benzoquinone.
The inhibitor is added in an amount effective to inhibit etching of the surface. Generally, as the concentration of the alkaline component increases, the concentration of the inhibitor required will also increase.
Also, as will be discussed below,~since "soft" water tends to ba more corro-sive than "hard'l water, a greater concentration of inhibitor will generally be required when the cleaning solutions are formulated using soft water than will be required when formulated with hard waterO Preferably, the amount of inhibitor in the solution will be at least about 0.02 g/l, and more prefer-ably will be about 0.02 g/l to about 0.0~ g/l. Concentrations greater than ~ t7(~
0.06 g/l may be effectively employed but the resultant increase in cost is not generally offset by a greater inhibition of etching.
It has been discovered that the addition of a poly~
electrolyte to tile cleaning solu~ions of the invention provides a solution that may be effectively employed regardless of the hard-ness of the water used to formulate the solution without generally experiencing precipitation of the calcium and magnesium ions that cause water hardness. Such precipitation is a problem since it may result in sediment that may, for example, clog spray nozzles when spraying is the chosen method of application.
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Polyelectrolytes are high molecular weight electrolytes of either natural orlgin, such as proteins, or of a synthetic nature, such as polymerized organic acids. Since the polyelectrolytes in solution do not dissociate to give a uniform distribution of positive and negative ions, as do simple electrolytes, the ions of one sign are bound to the polymer chain. Thus, Eor instance, the negative charges may be in the polymer chain, and only positive ions will be free to diffuse through the solvent.
Hardness is a characteristic of water generally accepted to represent the total concentration of calcium and magnesium ions. Other polyvalent cations that are seldom present in more than trace amounts may also contribute to hardness. Determination of hardness may be made by titration as set forth in "Standard Methods of Test for Hardness in Water", Designation D 1126-67 (Reapproved 1974) published by the American Society for Testing and Materials. Hardness may be given in parts per million (ppm) of calcium carbonate e ~ valent. The higher the value, the greater the hardness. Water hardness may vary greatly from one plant site to another.
Generally, water havlng a hardness of less than about 100 ppm may be considered "soft" whereas water having a hardness above about 100 ppm may be considered "hard".
In scme coastal regions the hardness may be only about 50 ppm to about 100 ppm and may increase to about 300 ppm where the water runs at some point through limestone deposits. In some areas of the midwest, the hardness may be about 400 ppm to about 500 ppm. Precipitation ~ 3~ ~ ~
will generally be experienced to a greateT extent as the hardness of the water increases. As hardness decreases, the water may tend to become more corrosive. Therefore, a polyelectrolyte is prefer-ably, but optionally added to the cleaning solutions of the pre-sent invention.
Tlle polyelectrolyte, when aclded, may be any of the com-po~mds known to the art to prevent precipitation o-f the minerals that cause water hardne$s. If a polyelectrolyte is selected that does not contain phosphate, certain advantages may be realized.
An important advantage is that the plant effluent will not contain phosphates since phosphates may be considered environmentally objectionable. Additionally, the allcali metal tripolyphosphates, which have previously been employed, may have the deleterious effect of promoting etching or detinning. Thus, polyelectrolytes preferred for use in the cleaning solutions of the present inven-tion are polyelectrolytes such as Gantrez, S-95*, manufactured by GAF Corporation, and Tamol 960*, manufactured by Rohm and Haas Company. These polymers do not promote detinning and may inhibit etching to some extent.
Ihe polyelectrolyte, when added, is preferably added in an amount effective to substantially prevent precipitation of the calcium and magnesium ions that are the primary cause of water hardness. Generally, greater amounts of polyelectrolyte will be required when the hardness of the water is high than when the hardness of the water is low. Preferably, the amount of poly-electrolyte will be at least about 0.1 g/1 and more preferably from about 0.1 g/1 to about 1 g/1. Concentrations *Trade Mark 7v~ L F
in excess of l g/1 may be present in the cleaning solutions but, generally, higher concentrations will not result in a significant improvement in the desired effect.
It is preferred but not essential to add one or more surfactants to the aqueous alkaline cleaning~solutions of the present invention. Additionally, when a surfactant is added that is not a low foaming surEactant/ a defoaming agent is desirably added~ A defoamer is desirable in such a case since foaming can present a serious problem to a commercial operation in that it may delay or shut down the cleaning line. Such materials enhance the performance of the cleaning solution but are not the essence of the invention since they are used to perform functions essentially similar to the function they perform in prior art solutions. The presence or absence of surfactants has been found to have no noticeable effect as far as inhibiting or promoting the etching of a tin surface by the cleaning solution.
:
Exemplary of the surfactants and wetting agents that can be employed in the cleaning solutions are ethoxy-lated straight chained alcohols and octyl or nonyl phenoxy polyethoxyethanol. Generally, nonionic surfactants are pre-ferred since they are low foaming~
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When s~rfactants are added, it is preferred that the cleaning solutions contain at least about 0.2 g/1 of one or more surfactants. A particularly preferred amount is from about 0.2 9/1 to about 0.5 g/l.
Tin surfaces may be c]eaned by contacting the sur-face with the aqueous alkaline c:leaning solutions of the present invention for a time and at a temperature effective to remove soil, lubricants or other such surface contaminants therefrom without visibly etching the tin surface. Generally, the solution temperature will be at least about 100F. A
preferred range is from about 100~ to about 130F, and more preferably from about 115F to about 125F. The temperature employed may tend to be higher for solutions having low concentrations of alkaline components than for solutions having higher concentrations of alkaline components. Thus, the treatment temperature may tend to vary somewhat inversely with the pH of the cleaning solution.
The time of treatment will generally depend on the method of application. A preferred method of appli-cation is spraying and when this method is used the treat-ment time will tend to decrease as the spraying pressure increases. ~eans for spraying as presently known in the art generally operate at spraying pressures of about 25 psi to about 35 psi and treatment times of about 40 seconds to about one minute may be sufficient to produce a water-break-free surface. I~eans for spraying at pressures of .~ a ~
60 psi to 100 psi are known but no-t generally used at present and may employ effective tre.atment times of about 1 to 5 seconds. Spraying is merely exemplary of the methods of application. Any conventional means known to the art may be used to contact the tin-plated surface with the cleaning solution.
The treatment time will also tend to increase the longer the interval between manufacture of the tin-plated metal article and the cleaning thereof. With drawn and ironed tin-plated steel cans, an interval of as little as fifteen minutes may noticeably result in an increased cleaning time. Additionally, the treatment time may vary depending on the type of lubricant used in the manufacturing process; some lubricants being more readily removed than others.
Application times of up to about 30 minu~es have been employed for purposes of determining the extent to which the present cleaning solutions will inhibit etching of the tin and it has been determined that a tin-plated surface may be contacted with the present solutions for up to about 30 minutes without etching the tin. In actual practice, however, it is contemplated that the shortest time effec-tive to produce a water-break-free surface without etching the tin will be employed in applying the present compositions to the tin surface to be cleaned in order to realize the greatest cost efficiency. After the tin surface is treated with the cleaning composition, the surface will generally be rinsed at least once with tap water and then may be rinsed with deionized water and dried at elevated temperature, preferably from about 350 to about 400F.
Thus, surprisingly, the present compositions, when formulated as an aqueous alkaline cleaning solution and contacted with a tin-plated me-tal surface for a period as long as about 30 minutes, will not visi~ly etch the tin. The present solutions, therefore, provide signifi-cantly increased protection against etching and corrosion over the prior art solutions in the event of line stoppage or similar such prolonged exposures to the cleaning solu-tions. Additionally, whereas the prior art solutions have required temperatures in excess of 140F in order to effectively clean the tin surface to produce a water-break-free surface withoutvisibly etching the tin, the present cleaning solutions may be effectively employed at tempera~
tures as low as at least about 100F and may preferably be employed at temperatures of from about 100F to about 130F. Thus, significant savings in energy costs may be realized using the solutions of the present invention, which solutions may be effectively applied at temperatures as much as 40 degrees less than those of the prior art solutions to produce water-break-free tin-plated surfaces that are not visibly etched.
The cleaner of the present invention may be formulated as an aqueous concentrate or as a solid cleaning composition to be added to water to produce the aqueous alkaline cleaning solutions of the present invention.
As an aqueous concentrate the cleaner is formu-lated such that when the aqueous concentrate is added to water at a concentration of about 0.5% to about 2% by volume it produces an aqueous alkaline cleaning solution having a pH of about 11 to about 13 for cleaning tin surfaces to substantia:Lly remove soil, lubricants or other contaminants -16~
therefrom without visibly etching the tin surface, even at low solution temperatures, and comprises an alkaline component in an amount effective to substantially remove said contaminants from the tin surface, and an inhibitor ln an amount effective to inhibit etching of the surface. The inhibitor is a compound as defined above. The concentrate may preferably be added to water at a concentration of about 1~ to about
2~ by volume.
The alkaline cornponent, as defined above, may preferably comprise up to about 770 grams per liter of the concentrate and more preferably may be present at from about 250 to about 500 grams per liter of the concentrate. The inhibitor may preferably comprise at least about 2 grams per liter of concentrate and more preferably may be present at from about 2 to about 6 grams per liter of the concentrate.
- The concentrate may optionally contain a poly-electrolyte and/or one or more surfactants. The poly-electrolyte, as defined above, may preferably be added in an amount effective to substantially prohibit precipi-tation of the calcium and magne-sium ions that are the primary cause of water hardness, and more preferably may be added at from about 1~ to about 20 grams per liter of concentrate.
- As a solid cleaning composition the cleaner is formulated such that ~hen '~he solld cleanins composition is added to water at a concentration of from about 3 g/l to about 7 g/1 it produces an aqueous alkaline cleaning solution having a pH of about 11 to about 13 for cleaning tin surfaces to substantially remove soil, lubricants or 't~
other contaminants therefrom without visibly etching the tin surface, even at low solution temperatures, and comprises an alkaline component in an amount effective to substantially remove said contaminants rom the tin surface, and an inhibitor in an amount effective to inhibit etching of the surface. The inhibitor is a compound as defined ab~ove.
The cleaning composition may preferably be added to water at a concentration of about 4.6 g/l to about 6.7 g/l.
The alkaline component, as defined above, may preferably comprise at least about 15% by weight of the composition. The inhibitor may preEerably comprise at least about 0.1% by weight of the composition. A particu-larly preferred concentration is from about 0.5~ to about 2% by weight of the composition.
The composition, as defined above, may optionally contain a polyelectrolyte in an amount effective to sub-stantially prevent precipitation of the calcium and mag-nesium ions that are the primary cause of water hardness.
A preferred concentration for the polyelectrolyte is from 0% to about 10% by weight of the composition and more preferably from about 3% to about-10% by weight of the composition.
The cleaning composition may optionally contain, as diluents and the like, compounds that may be characterti~ed as inert with respect to any possible positive or negative influence on the cleaning and non-etching properties of the cleaning solutions of the invention. Exemplary of such compounds is sodium sulphate.
The following examples present illustrative but non-limiting embodiments of the present invention.
Examples In each of the following examples, sets of drawn and ironed tin-plated steel cans (hereinafter, DI cans) were contacted with the cleaning solution of the particular ex-ample. The cans were used within 24 hours of manufacture and were not treated in any way prior to being contacted with the cleaning solutions of the invention.
Cleaning compositions were prepared having the concentrations of components indicated in Table I. Each com-position is identified by a number and a subscript "c".
A specific amount, in grams, of each composition as indicated in Table II was then added to 6 liters of water to produce aqueous alkaline cleaning solutions having the concentrations of components indicated in Table III. Each cleaning solution is identified by the number of the composition used in its formulation along with the subscript "sl'. Surfactants were added in the concentrations indicated in Table III.
The chosen method of contacting the sets of cans with the cleaning solution in each example was spraying.
The solutions were sprayed at about 25psi for the times and at the temperatures defined in each example. The cans were then rinsed with water and visually observed for etching and appearance.
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The alkaline cornponent, as defined above, may preferably comprise up to about 770 grams per liter of the concentrate and more preferably may be present at from about 250 to about 500 grams per liter of the concentrate. The inhibitor may preferably comprise at least about 2 grams per liter of concentrate and more preferably may be present at from about 2 to about 6 grams per liter of the concentrate.
- The concentrate may optionally contain a poly-electrolyte and/or one or more surfactants. The poly-electrolyte, as defined above, may preferably be added in an amount effective to substantially prohibit precipi-tation of the calcium and magne-sium ions that are the primary cause of water hardness, and more preferably may be added at from about 1~ to about 20 grams per liter of concentrate.
- As a solid cleaning composition the cleaner is formulated such that ~hen '~he solld cleanins composition is added to water at a concentration of from about 3 g/l to about 7 g/1 it produces an aqueous alkaline cleaning solution having a pH of about 11 to about 13 for cleaning tin surfaces to substantially remove soil, lubricants or 't~
other contaminants therefrom without visibly etching the tin surface, even at low solution temperatures, and comprises an alkaline component in an amount effective to substantially remove said contaminants rom the tin surface, and an inhibitor in an amount effective to inhibit etching of the surface. The inhibitor is a compound as defined ab~ove.
The cleaning composition may preferably be added to water at a concentration of about 4.6 g/l to about 6.7 g/l.
The alkaline component, as defined above, may preferably comprise at least about 15% by weight of the composition. The inhibitor may preEerably comprise at least about 0.1% by weight of the composition. A particu-larly preferred concentration is from about 0.5~ to about 2% by weight of the composition.
The composition, as defined above, may optionally contain a polyelectrolyte in an amount effective to sub-stantially prevent precipitation of the calcium and mag-nesium ions that are the primary cause of water hardness.
A preferred concentration for the polyelectrolyte is from 0% to about 10% by weight of the composition and more preferably from about 3% to about-10% by weight of the composition.
The cleaning composition may optionally contain, as diluents and the like, compounds that may be characterti~ed as inert with respect to any possible positive or negative influence on the cleaning and non-etching properties of the cleaning solutions of the invention. Exemplary of such compounds is sodium sulphate.
The following examples present illustrative but non-limiting embodiments of the present invention.
Examples In each of the following examples, sets of drawn and ironed tin-plated steel cans (hereinafter, DI cans) were contacted with the cleaning solution of the particular ex-ample. The cans were used within 24 hours of manufacture and were not treated in any way prior to being contacted with the cleaning solutions of the invention.
Cleaning compositions were prepared having the concentrations of components indicated in Table I. Each com-position is identified by a number and a subscript "c".
A specific amount, in grams, of each composition as indicated in Table II was then added to 6 liters of water to produce aqueous alkaline cleaning solutions having the concentrations of components indicated in Table III. Each cleaning solution is identified by the number of the composition used in its formulation along with the subscript "sl'. Surfactants were added in the concentrations indicated in Table III.
The chosen method of contacting the sets of cans with the cleaning solution in each example was spraying.
The solutions were sprayed at about 25psi for the times and at the temperatures defined in each example. The cans were then rinsed with water and visually observed for etching and appearance.
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Z.C e~ .Y O N t`l ~1 R ~ h ~I cd ~ u~
~ ~~ O ~ O ~ O ~ ~ ¢
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~ ~ 1 H X :'C
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1 h P~ ~ o ~1 ~4 ~
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z -22a-.
Example 1 Sets of DI cans were sprayed, one set per solution, with cleaning solutions ls, 2s~ 3s and 4s' for 10 minutes at 123F. The results are sumrnarized in Table IV.
TABLE IV
Cleaning Solution Observation of Result 1 No detinning; water-break-s free cans; bright, rust-free surface 2s No detinning; water-break-free cans; bright, rust-free surface 3s No detinning; water-break-free cans; bright, rust-free surface 4s Severe detinning Example 2 Sets of DI cans were sprayed, one set per test, with cleaning solution 55for the times and at the tempera-tures indicated and the results are summarized in Table V.
7( ~
.
TABLE V
Solution Treatment Observed Temperature Time Result 125F 1 minute No detinning;
bright, rust-free surface; water-break-free cans 125F 30 minutes No~detinning;
bright, rust-free surface; water-break-free cans 127F 1 minute No detinning;
bright, rust-free surface; water-break-free cans 127F 30 minutes No detinning;
bright, rust-free-surface; water-break-free cans Example 3 Sets of DI cans were sprayed w-th cleaning solutions 65, 7s~ 8S~ and 9s~ one set per test, for the tlmes and at the temperatures indicated. The results are summarized in Table VI.
TABLE VI
Cleaning Solution Treatment Observed Solution Temperature Time Result 6s 120 1 minute No detinning;
bright, rust-free - surface; water-break free cans 7s 120 1 minute No detinning; bright, rust-free surface; water-break-free cans 120 1 minute No detinning; bright, rust-free surface; water-break-free cans 9s 1.20 1 minute No detinning; bright, rust~free surface; water-break-free cans -.
T~BLE VI (cont'd) Cleaning Solution Treatment Observed Solution Temperature Time Result ~s 120 15 minutes No detinning; bright, rust-fxee surface; water-break-~ree cans 9s 120 30 minutes No detinnlng; bright, rust-free surface; wa-ter-break-free cans 9s 124 1 minute No detinning; briyht, rust-free surface; water-break-free cans 9s 124 15 minutes No detinning; bright, rust-free surface; water-break-free cans 9s 124 30 minutes No detinning; bright, rust-free surface; water-break free cans Example 4 Sets of DI cans were sprayed with cleaning solu-tions 10S, 11S, and 12SI one set per test, for the times and at the temperatures indicated. The results are summarized in ~able VII.
: TABLE VII
Cleaning Solution Treatment Observed Solution Temperature Time Result 105 125F 1 minute No detinning; bright, rust-free surface; water-break-free cans lls 125F 1 minute No detinning; bright, rust-free surface; water-break-free cans - 12S 125F 1 minute No detinning; bright, rust-free surface; water-break-free cans 105 125F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 115 125F 30 minutes No detinning; bright, rust-free surface; water-break-free cans -25- .
i 3.~
.
TABLE VII (cont'd) Cleaning Solution Treatment Observed Solution Temperature Time Result 12s 125F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 105 150F 1 minute No detinning; bright, rust~free surface; water-break-free cans llS 150F 1 minute No detinning; bright, rust-free surface; water-break-free cans 125 150F 1 minute No detinnlng; bright, rust-free surface; water-break-free cans 0s 150F 30 minutes No detinning; bright, rust-free surface; water-break-free cans llS 150F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 12S 150F 30 minutes No detinning; bright, rust-free surface; water-break-free cans Example 5 Aqueous concentrates were prepared having the concentrations of components indicated in Table VIII. These concentrates are designated 13 aq and 14 aq.
Aqueous alkaline cleaning solutions 135 and 145 were formulated, respectively, by diluting 11.4 milliliters of aqueous concentrate 13 aq to 1 liter with tap water and by diluting 10 milllliters of aqueous concentrate 14 aq to 1 liter with deionized water. Surfactants were added in the concentrations indicated. The cleaning solutions had the concentrations of components indicated in Table VIII.
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~ ¢ ~ ~ ~
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rY ~ N - ~ ~ H ~ h ~ 4 1 ~S h O H O ~ td Z~ ~ O ~ ~1 O ~
~ ¢ ~ ~ Z _H 1~ ~~'7Ct~ ~ Cl ~ P~ *
o~
Sets of DI cans were sprayed with cleaning solutions 13s and 14S, one set per test, for the times and at the temperatures indicated. The re-sults are summarized in Table IX.
*ABLE IX
Cleaning Solution Treatment Observed Solution Temperature Time Result 13 120F 1 minute No detinning; bright, rust-free surface; water-break-free cans 145 120F 1 minute No detinning; bright, rust-free surface; water-break-free cans 135 124F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 135 128F 30 minutes No detinning; bright, rust-free surface; water-break-free cans Example 6 Cleaning solutions 15S~ 165, and 175 were prepared using tap water and having the concentrations of components indicated in Table X. Solution 175 does not contain an inhibitor and thus, like cleaning solution 4s in Example 1, is presented for purposes oF comparison.
T~BLE X
COMPONENT CLEANING SOLUTION ~g/l) 155 16S 17s Inhibitor 1,4-dihydroxybenzene 0.05 0.05 X
Alkaline Compound 2 iO3 4.33 4.33 4 33 Polyelectrolyte Tamol 960 (manufactured by Rohm and Haas Company) 0.67 0.47 0.67 -TABLE X (cont'd) COMPONENT CLE~ING SOLUTION (g/l) Surfactant Poly-Tergent S-505-LF
~manufactured by Olin Corp.) 0.42 0.42 0.42 pH 12.4 12.4 12.4 Sets of DI cans were sprayed with cleaning solutions 15S, 165, and 17S, one set per test, at solution temperatures of 124F for the times indicated. The results are sumrnarized in Table XI.
TABLE XI
Cleaning Treatment Observed Solution Time Result 5s 1 minute No detinning; bright, rust-free surface; water break-free cans 165 1 minute No detinning; bright, - rust-free surface; water-break-free cans 1 minute Spotty whitening;
some detinning 155 30 minutes No detinning; bright, rust-free surface; water-breaX-free cans 165 30 minutes No detinning; bright, rust-free surface; water- I
- break-free cans 175 30 minutes Badly mottled dark surface; severe detinning ~.
,
~, O ~ ~ ~ h ~ h 0~ ~ I ~ r~
~ l ¢ ~0 ~ d ~ ~
c~ t.) ~ ' h t~ ~ ~: a U~C~ 4~ o ~ O O O
1 h P~ ~ o ~1 ~4 ~
Z h U)h ~d h ~H ~ ,t ~l o c~ ~ ~~ P~ m U~ ~`
z -22a-.
Example 1 Sets of DI cans were sprayed, one set per solution, with cleaning solutions ls, 2s~ 3s and 4s' for 10 minutes at 123F. The results are sumrnarized in Table IV.
TABLE IV
Cleaning Solution Observation of Result 1 No detinning; water-break-s free cans; bright, rust-free surface 2s No detinning; water-break-free cans; bright, rust-free surface 3s No detinning; water-break-free cans; bright, rust-free surface 4s Severe detinning Example 2 Sets of DI cans were sprayed, one set per test, with cleaning solution 55for the times and at the tempera-tures indicated and the results are summarized in Table V.
7( ~
.
TABLE V
Solution Treatment Observed Temperature Time Result 125F 1 minute No detinning;
bright, rust-free surface; water-break-free cans 125F 30 minutes No~detinning;
bright, rust-free surface; water-break-free cans 127F 1 minute No detinning;
bright, rust-free surface; water-break-free cans 127F 30 minutes No detinning;
bright, rust-free-surface; water-break-free cans Example 3 Sets of DI cans were sprayed w-th cleaning solutions 65, 7s~ 8S~ and 9s~ one set per test, for the tlmes and at the temperatures indicated. The results are summarized in Table VI.
TABLE VI
Cleaning Solution Treatment Observed Solution Temperature Time Result 6s 120 1 minute No detinning;
bright, rust-free - surface; water-break free cans 7s 120 1 minute No detinning; bright, rust-free surface; water-break-free cans 120 1 minute No detinning; bright, rust-free surface; water-break-free cans 9s 1.20 1 minute No detinning; bright, rust~free surface; water-break-free cans -.
T~BLE VI (cont'd) Cleaning Solution Treatment Observed Solution Temperature Time Result ~s 120 15 minutes No detinning; bright, rust-fxee surface; water-break-~ree cans 9s 120 30 minutes No detinnlng; bright, rust-free surface; wa-ter-break-free cans 9s 124 1 minute No detinning; briyht, rust-free surface; water-break-free cans 9s 124 15 minutes No detinning; bright, rust-free surface; water-break-free cans 9s 124 30 minutes No detinning; bright, rust-free surface; water-break free cans Example 4 Sets of DI cans were sprayed with cleaning solu-tions 10S, 11S, and 12SI one set per test, for the times and at the temperatures indicated. The results are summarized in ~able VII.
: TABLE VII
Cleaning Solution Treatment Observed Solution Temperature Time Result 105 125F 1 minute No detinning; bright, rust-free surface; water-break-free cans lls 125F 1 minute No detinning; bright, rust-free surface; water-break-free cans - 12S 125F 1 minute No detinning; bright, rust-free surface; water-break-free cans 105 125F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 115 125F 30 minutes No detinning; bright, rust-free surface; water-break-free cans -25- .
i 3.~
.
TABLE VII (cont'd) Cleaning Solution Treatment Observed Solution Temperature Time Result 12s 125F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 105 150F 1 minute No detinning; bright, rust~free surface; water-break-free cans llS 150F 1 minute No detinning; bright, rust-free surface; water-break-free cans 125 150F 1 minute No detinnlng; bright, rust-free surface; water-break-free cans 0s 150F 30 minutes No detinning; bright, rust-free surface; water-break-free cans llS 150F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 12S 150F 30 minutes No detinning; bright, rust-free surface; water-break-free cans Example 5 Aqueous concentrates were prepared having the concentrations of components indicated in Table VIII. These concentrates are designated 13 aq and 14 aq.
Aqueous alkaline cleaning solutions 135 and 145 were formulated, respectively, by diluting 11.4 milliliters of aqueous concentrate 13 aq to 1 liter with tap water and by diluting 10 milllliters of aqueous concentrate 14 aq to 1 liter with deionized water. Surfactants were added in the concentrations indicated. The cleaning solutions had the concentrations of components indicated in Table VIII.
r -~4 Z ~G~
O ~H ~ O X O ~ X X
E ~ J N O O ,-~
o z ¢
LLl U) ~ X o~ ~ ~ ~ O
C~ ~ ~ ~ ~ O O O O
~D
U~
~ ~ ~ X U) X X X
z H LLl H o, O X O n O X X X
~ ¢ ~ ~ ~
~1 ¢ ';
h h ~S ~
~0 ~¢ a~
h ct :S h ~ ~
h H r1 cl l O
h t~ O~ O ~ ~h; 3 ~ ~ ~
q O ~ ~, N ~ V ~d V ~d ~r~ h V ~H O ~H O
~ V ~ h ~ h ,J~
O O C~ ~ O
~ ~ ~ U~
U~ ~ ~ V~h h I ~ ~ ~) h ~
Z a.~ * h Vu~S ~ V h V ~ ~d ~1 ~ :~ ~ ~)I a~ N ~0~ a~ . ,~
Z; r1 ~ O r~ r-l O V4~ 1 O ~ ~ ~ o u~ ~Il~ ~ ~~d ~d g h ~ ~
rY ~ N - ~ ~ H ~ h ~ 4 1 ~S h O H O ~ td Z~ ~ O ~ ~1 O ~
~ ¢ ~ ~ Z _H 1~ ~~'7Ct~ ~ Cl ~ P~ *
o~
Sets of DI cans were sprayed with cleaning solutions 13s and 14S, one set per test, for the times and at the temperatures indicated. The re-sults are summarized in Table IX.
*ABLE IX
Cleaning Solution Treatment Observed Solution Temperature Time Result 13 120F 1 minute No detinning; bright, rust-free surface; water-break-free cans 145 120F 1 minute No detinning; bright, rust-free surface; water-break-free cans 135 124F 30 minutes No detinning; bright, rust-free surface; water-break-free cans 135 128F 30 minutes No detinning; bright, rust-free surface; water-break-free cans Example 6 Cleaning solutions 15S~ 165, and 175 were prepared using tap water and having the concentrations of components indicated in Table X. Solution 175 does not contain an inhibitor and thus, like cleaning solution 4s in Example 1, is presented for purposes oF comparison.
T~BLE X
COMPONENT CLEANING SOLUTION ~g/l) 155 16S 17s Inhibitor 1,4-dihydroxybenzene 0.05 0.05 X
Alkaline Compound 2 iO3 4.33 4.33 4 33 Polyelectrolyte Tamol 960 (manufactured by Rohm and Haas Company) 0.67 0.47 0.67 -TABLE X (cont'd) COMPONENT CLE~ING SOLUTION (g/l) Surfactant Poly-Tergent S-505-LF
~manufactured by Olin Corp.) 0.42 0.42 0.42 pH 12.4 12.4 12.4 Sets of DI cans were sprayed with cleaning solutions 15S, 165, and 17S, one set per test, at solution temperatures of 124F for the times indicated. The results are sumrnarized in Table XI.
TABLE XI
Cleaning Treatment Observed Solution Time Result 5s 1 minute No detinning; bright, rust-free surface; water break-free cans 165 1 minute No detinning; bright, - rust-free surface; water-break-free cans 1 minute Spotty whitening;
some detinning 155 30 minutes No detinning; bright, rust-free surface; water-breaX-free cans 165 30 minutes No detinning; bright, rust-free surface; water- I
- break-free cans 175 30 minutes Badly mottled dark surface; severe detinning ~.
,
Claims (40)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for cleaning tin surfaces to substantially remove soil, lubricants or other contaminants therefrom without visibly etching the tin surface, comprising contacting said surface at a temperature effective to substantially remove said contaminants from the tin surface with an aqueous cleaning solution having a pH about 11 to about 13 comprising an alkaline component in an amount effective to substantially remove said contaminant from the tin surface, and an inhibitor in an amount effective to inhibit etching of the surface, said inhibitor being selected from the group consist-ing of quinones, substituted quinones, and substituted benzenes having at least two hydroxy substituents.
2. A process according to claim 1, wherein the cleaning temperature is about 100 to about 130°F.
3. A process according to claim 1 wherein the concentration of alkaline component in the cleaning solution is about 3 g/l to about 5 g/l.
4. A process according to claim 3 wherein the concentration of the inhibitor in the cleaning solution is about 0.02 g/l to about 0.06 g/l.
5. The process according to claim 4 wherein the inhibitor is selected from the group consisting of catechol, resorcinol, hydroquinone, hydro-xyhydroquinone, gallic acid, 1,3,5-trihydroxybenzene, 1,2,4,5-tetrahydroxy-benzene, 1,4-benzoquinone, 1,2-benzoquinone, .alpha.-napthaquinone, and .beta.-naptha-quinone.
6. The process according to claim 4 wherein the inhibitor is selected from the group consisting of substituted benzenes, having at least two or more hydroxy substituents in an ortho, meta, para, symmetric or assymmetric configuration, and quinones and substituted quinones of the formulae wherein:
R1, R2, R3 and R4 are hydrogen, hydroxy, alkyl, halo, carboxyl, alkoxy, nitro or cyano; or R1 and R2 are together an alkyldienyl group, and together with the quinone ring to which they are attached, form a napthaquinone.
R1, R2, R3 and R4 are hydrogen, hydroxy, alkyl, halo, carboxyl, alkoxy, nitro or cyano; or R1 and R2 are together an alkyldienyl group, and together with the quinone ring to which they are attached, form a napthaquinone.
7. The process according to claim 3 wherein the alkaline component of the cleaning solution is selected from the group consisting of alkali metal hydroxides, carbonates, and silicates, ammonium hydroxides and carbonates, and mixtures thereof.
8. The process of claim 7 wherein the alkaline component comprises a mixture of sodium metasilicate, sodium carbonate and a compound selected from the group consisting of sodium hydroxide and potassium hydroxide.
9. The process of claim 1 wherein the cleaning solution includes a polyelectrolyte in an amount effective to substantially prevent precipita-tion.
10. The process of claim 9 wherein the amount of polyelectrolyte is at least about 0.1 g/l.
11. The process of claim 1 wherein the cleaning solution includes at least about 0.2 g/l of one or more surfactants.
12. The process of claim 11 wherein the surfactant comprises about 0.2 g/l to about 0.5 g/l.
13. The process of claim 11 or 12 wherein the cleaning solution in-cludes a low foaming nonionic surfactant.
14. The process of claim 1 wherein the surface is contacted with the cleaning solution by spraying.
15. The process of claim 1 including rinsing the surface with water after it is contacted with the cleaning solution.
16. An aqueous cleaning composition having a pH of about 11 to about 13 for cleaning tin surfaces to substantially remove, soil, lubricants or other contaminants therefrom without visibly etching the tin surface, at temperatures between about 100°F to about 130°F, comprising an alkaline component in an amount effective -to substantially remove said contaminants from the tin surface and an inhibitor, in an amount effective to inhibit etching of the surface, selected from the group consisting of quinones, substituted quinones, and substituted benzenes having at least two or more hydroxy substituents in ortho, meta, para, symmetric or assymetric configurations.
17. A cleaning solution according to claim 16 wherein the quinones and substituted quinones are of the formulae wherein:
R1, R2, R3 and R4 are hydrogen, hydroxy, halo, alkoxy, alkyl, carboxyl, nitro, and cyano; or R1 and R2 form an alkyldienyl group, and together with the quinone ring to which they are attached, form a napthaquinone.
R1, R2, R3 and R4 are hydrogen, hydroxy, halo, alkoxy, alkyl, carboxyl, nitro, and cyano; or R1 and R2 form an alkyldienyl group, and together with the quinone ring to which they are attached, form a napthaquinone.
18. A cleaning solution according to claim 16 wherein the substituents on the benzene ring, in addition to the hydroxy substituents, are hydrogen, halo, alkyl, alkoxy, carboxyl, nitro, or cyano.
19. A cleaning solution according to claim 16 wherein the inhibitor is selected from the group consisting of 1,2-benzoquinone, 1,4-benzoquinone, catechol, resorcinol, 1,4-dihydrobenzoquinone, hydroxy hydroquinone, 1,3,5-trihydroxy-benzene, 1,2,4,5-tetrahydroxybenzene.
20. A cleaning composition according to claim 16 or 17 wherein the inhibitor is selected from the group consisting of benzoquinone, 1,4-benzoquinone, and substituted quinones.
21. A cleaning solution according to claim 16 wherein the inhibitor is selected from the group consisting of dihydroxybenzenes and quinones.
22. A cleaning composition according to claim 16 wherein the amount of inhibitor is about 0.02 g/l to about 0.06 g/l.
23. A cleaning composition according to claim 16 wherein the alkaline component of the cleaning solution is selected from the group consisting of alkali metal hydroxides, carbonates, and silicates, ammonium hydroxides and carbonates and mixtures thereof.
24. A cleaning composition according to claim 23 wherein the alkaline component comprises a mixture of sodium metasilicate, sodium carbonate and a compound selected from the group consisting of sodium hydroxide and potassium hydroxide.
25. A cleaning composition according to claim 16 including a polyelectrolyte in an amount effective to substantially prevent precipitation.
26. A cleaning composition according to claim 25 wherein the amount of polyelectrolyte is at least about 0.1 g/l.
27. A solid cleaning composition which when added to water at a concentration of from about 3 g/l to about 7 g/l produces an aqueous alkaline cleaning solution having a pH of about 11 to about 13 for cleaning tin surfaces to substantially remove soil, lubricants or other contaminants therefrom without visibly etching the tin surface, and which comprises an alkaline component in an amount effective to substantially remove said contaminants from the tin surface, and an inhibitor in an amount effective to inhibit etching of the surface, said inhibitor being selected from the group consisting of quinones, substituted quinones, and substituted benzenes having at least two or more hydroxy substituents in an ortho, meta, para, symmetric or assymetric configuration.
28. A solid cleaning composition according to claim 27 wherein the quinones and substituted quinones are of the formulae wherein:
R1, R2, R3 and R4 are hydrogen, hydroxy, halo, alkoxy, alkyl, carboxyl, nitro, and cyano; or R1 and R2 form an alkyldienyl group, and together with the quinone ring to which -they are attached, form a napthaquinone.
R1, R2, R3 and R4 are hydrogen, hydroxy, halo, alkoxy, alkyl, carboxyl, nitro, and cyano; or R1 and R2 form an alkyldienyl group, and together with the quinone ring to which -they are attached, form a napthaquinone.
29. A solid cleaning composition according to claim 27 wherein the substituents on the benzene ring are, in addition to the hydroxy substituents, hydrogen, halo, alkyl, carboxyl, alkoxy, nitro, or cyano.
30. A solid cleaning composition according to claim 27 wherein the inhibitor is selected from the group consisting of catechol, resorcinol, hydroquinone, hydroxyhydroquinone, 1,3,5-trihydroxybenzene, 1,2,4,5-tetrahydroxy benzene, 1,4-benzoquinone, and 1,2-benzoquinone.
31. The solid cleaning composition of claim 27 wherein the alkaline component comprises at least about 15% by weight of the composition.
32. The solid cleaning composition of claim 27 wherein the alkaline component is selected from the group consisting of alkali metal hydroxides, carbonates and silicates, ammonium hydroxides and carbonates, and mixtures thereof.
33. The solid cleaning composition of claim 27 wherein the inhibitor comprises at least about 0.1% by weight of the composition.
34. The solid cleaning composition of claim 27 including a polyelectrolyte in an amount effective to substantially prevent precipitation.
35. An aqueous concentrate which when added to water at a concentration of about 0.5% to about 2% by volume produces an aqueous alkaline cleaning solution having a pH of about 11 to about 13 for cleaning tin surfaces to substantially remove soil, lubricants or other contaminants, therefrom without visibly etching the tin surface and which comprises an alkaline component in an amount effective to substantially remove said contaminants from the tin surface, and an inhibitor, in an amount effective to inhibit etching of the surface, said inhibitor being selected from the group consisting of quinones, substituted quinones and substituted benzenes having at least two or more hydroxy substituents in ortho, meta, para or symmetric or assymmetric configurations.
36. The concentrate of claim 35 wherein the alkaline component comprises up to about 770 grams per liter of concentrate.
37. The concentrate of claim 35 wherein the inhibitor comprises at least about 2 grams per liter of concentrate.
38. The concentrate of claim 35 or 37 wherein the inhibitor is selected from the group consisting of catechol, resorcinol, hydroquinone, hydroxy hydroquinone, 1,3,5-trihydroxybenzene, 1,3,4,5-tetrahydroxybenzene, 1,4-benzoquinone and 1,2-benzoquinone.
39. The concentrate of claim 35 including a polyelectrolyte in an amount effective to substantially prevent precipitation.
40. The concentrate of claim 35 including one or more surfactants.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16356680A | 1980-06-27 | 1980-06-27 | |
| US163,566 | 1980-06-27 | ||
| US26875281A | 1981-06-08 | 1981-06-08 | |
| US268,752 | 1994-06-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170144A true CA1170144A (en) | 1984-07-03 |
Family
ID=26859753
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000380699A Expired CA1170144A (en) | 1980-06-27 | 1981-06-26 | Low temperature cleaner for metal surfaces |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1170144A (en) |
-
1981
- 1981-06-26 CA CA000380699A patent/CA1170144A/en not_active Expired
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