Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/08—Iron or steel
  • C23G1/088—Iron or steel solutions containing organic acids
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/46—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing oxalates
  • C23C22/47—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing oxalates containing also phosphates
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/12—Light metals
  • C23G1/125—Light metals aluminium

Definitions

• compositions of the present invention have multiple utilities, since they have been found to functionally interact with different types of metal surfaces in different ways to produce different useful results.
• compositions of the invention are useful in the acid cleaning of aluminum surfaces, in the deoxidizing and cleaning of stainless steels, and in the production of iron phosphate coatings on ferriferous surfaces to enhance the corrosion resistance and paint adhesion properties of such surfaces.
• a particularly severe aluminum cleaning problem is encountered in the production of aluminum cans for use as beverage containers, and the compositions of the present invention are outstandingly effective in this environment.
• aluminum sheet with the ordinary accumulations of manufacturing and warehouse soil on the surface, is subjected to a deep forming operation termed drawing and ironing.
• drawing oil a water dispersed lubricating oil
• the dirty, oily, can so formed must then be cleaned so that a chemical pretreatment designed to enhance paint bonding and corrosion resistance can be applied.
• the chemical pretreatment is then followed by a painting or lacquering operation involving one or more organic siccative finishes.
• the object of the cleaning operation has been defeated.
• the equipment difficulties caused by sludge can include clogging of spray heads, and the formation of hard scaly deposits on tank heating coils which interfere with heat transfer into the bath. Even if such major difiiculties are avoided, the buildup sludge in the cleaning equipment does require periodic shutdowns for costly sludge removal operations.
• surfactants are often desirable components of a cleaning material, to aid in the wetting of the surface being cleaned, and in the removal of soils. It is also known that many surfactants contribute to the establishment of stable emulsions of oil and water. Yet a stable oil-in-water emulsion in the cleaning solution is undesirable. If the oil emulsion is stabilized by the surface-active components of a cleaner, the oil concentration will build up as the cleaning solution is recycled, and the emulsion will eventually tend to break at a relatively high oil concentra tion. Under such circumstances, there is a great danger that the breaking of the emulsion will occur when the cleaning solution is in contact with the aluminum surface.
• the cleaning solution have a set of surface active properties which meet somewhat incompatible performance requirements: the solution should have sufficient activity to lift the emulsified drawing oil (and other soils) from the surface, and at the same time, have a low enough surface activity to enable the unstable drawing oil emulsion to readily break, thus allowing the oil to separate and float on the surface of the cleaning solution tank, where it may readily be removed, and thereby prevented from being recycled with the cleaning solution back to the aluminum surfaces being cleaned.
• the type of cleaning equipment which is usually used for cleaning aluminum cans is of the spray type, including a cabinet having spray nozzles in it and a solution tank positioned beneath the cabinet to catch solution falling from the cans after contacting them.
• the solution tank contains the heating element. Solution is pumped from the tank through lines to the spray nozzles where it is sprayed against cans being conveyed through the cabinet and then falls back into the solution tank.
• a cleaning solution is used in such apparatus it can be seen that it is subjected to considerable turbulence. For this reason it is desirable that the solution be of the low-foaming type.
• compositions capable of cleaning aluminum even in the severe cleaning environment of an aluminum can operation, which compositions overcome all of the problems outlined above.
• the removal of dirt and scale from stainless steel has long been regarded as a difiicult metal-cleaning problem.
• the oxide scales resulting from annealing operations are difficult to remove effectively and safely.
• the compositions of the present invention are effective to remove oxide from stainless steel surfaces, especially oxide resulting from annealing, and it has been discovered that they have the added effect of brightening the stainless steel following oxide removal.
• iron phosphate coatings to ferriferous surfaces has long been practiced for the purpose of imparting corrosion resistance and good paint-adhesion properties to the ferriferous surface.
• the art has developed a variety of formulations of iron phosphate coating materials for use in conventional coating apparatus of the dip or spray type.
• a newer method of applying chemically protective coatings to metals has come into wide use recently. This method is known as reverse roll coating.
• This coating application process the coating solution is applied to a moving metal surface by means of a feed roller whose surface is wetted with the coating solution and is rotating in a direction reversed or opposite to that in which the metal surface is moving past the roller surface.
• This coating technique is particularly suited to applying coating solution to metal in strip form.
• the reverse roller coating technique has a number of advantages over other techniques for applying conversion coating solutions to metal surfaces. For example, with respect to that method of applying the coating solution by moving the metal surface past or over a roll or rollers which are rotating or moving in the same direction as the metal surface, the reverse roller coating technique has the advantages that the coatings can be applied to the surface with greater rapidity and without sacrificing coating quality; in many applications, an improvement in coating quality is obtained. These advantages are realized also when the reverse roller coating technique is compared with other application methods, such as spraying and immersion methods.
• compositions and methods for the application of iron phosphate coatings to ferriferous surfaces by the use of reverse roller coating techniques;
• compositions of the present invention are multicom ponent systems, and for convenience the various components will be discussed separately, although it must be understood that the components do not function in isolation from one another, but cooperate to produce new and improved results discussed above.
• compositions of the invention are concentrates which may be diluted with water to a use concentration appropriate for the particular application, but the invention may also be practiced by making solutions at use concentration directly from raw materials.
• the method aspects of the invention will be brought out further in the following claims.
• compositions of the invention are aqueous acidic solutions containing both phosphoric acid and sulphuric acid. By utilizing these acids together, desirable effects are obtainable which are unavailable if only one is employed.
• Phosphoric acid is a desirable material from the standpoint of the cleaning utilities of the invention since it does not attack the metal cleaned (aluminum or stainless steel) or the metal normally used in the cleaning equipment (stainless steel) as vigorously as the stronger inorganic acids which are used from time to time in acidic cleaners.
• the phosphoric acid serves as a source for phosphate ion.
• the sulphuric acid portion of the acid component serves in all of the use contexts discussed above to lower the pH of the solutions, without completely obliterating the underlying character of the solutions as phosphate-type materials.
• a blend of phosphoric and sulphuric acid yields a number of further advantages in the context of aluminum can cleaning, when compared to other acidic aluminum cleaning compositions utilizing phosphoric acid only.
• the use of sulphuric acid with the phosphoric acid makes possible the use of a relatively lower phosphate concentration, and, as pointed out above, results in a lower solution pH. These two circumstances contribute materially to increasing the aluminum-carrying capacity of the solution over earlier solutions using phosphoric acid only.
• the term "aluminum-carrying capacity is an expression intended to describe the ability of the solutions to hold aluminum in soluble form.
• the sludge which will tend to form is aluminum phosphate, which is soluble below a pH of about 2.0.
• the use of sulphuric acid in conjunction with phosphoric acid results in a solution having a normal pH below 2.0, thus increasing the aluminum carrying capacity.
• sulphuric acid serves as a source of hydrogen ions, relieving the phosphoric acid in part from this function, the relative phosphate concentration can be lower, and the driving force for the formation of aluminum phosphate is reduced.
• the blend of sulphuric and phosphoric acids is also superior to the performance of either type of acid alone for the same purpose.
• the action of the solutions on stainless steel is faster than that of solutions based on phosphoric acid alone, but is not as severe as the action resulting from the use of solutions based on sulphuric acid alone.
• the acid component should be from about 0.001 percent to about 0.005 percent for aluminum cleaning applications, from about 0.003 percent to about 0.015 percent for stainless steel cleaning and brightening applications, and from about 0.0015 percent to about 0.015 percent for reverse roll iron phosphating applications. Within each of the foregoing ranges are preferred concentration ranges for the acid component. For aluminum cleaning it is preferred that the concentration be between about 0.0025 percent and 0.0035 percent, for stainless steel cleaning and brightening, between about 0.004 percent and about 0.0075 percent and for reverse roll iron phosphating between about 0.0075 percent and about 0.0105 percent.
• the percentages just given are weight percentages calculated on the basis of 66 B. sulfuric acid and 75 percent phosphoric acid as acid sources.
• the foregoing desirable effects have also been found to be dependent upon the ratios of sulphuric acid to phosphoric acid.
• Such ratios may be most conveniently expressed as volume ratios of sulphuric acid (as 66 8. H SO to phosphoric acid (as 75 percent H PO,).
• the ratio of sulphuric acid to phosphoric acid to produce the desired efi'ects runs between about 0.5 to 1 to about 1.5 to l, with a preferred ratio being in the range of about 0.8 to l to about 1.2 to l.
• a second component of the compositions of the invention is a surfactant component. While various single surface active agents may be used as well as many various blends of surface active agents, 1 have found that a blend of a primary ethoxylated alcohol sold under the name of Neodol -7, and a modified polyethyoxylated straight chain alcohol, sold under the name of Triton DF-18, provides very satisfactory results in all of the above discussed areas of utility, especially in the aluminum cleaning context where an emulsifiable oil is present as a surface soil.
• the total concentration of the surfactant component should be from about 0.0010 percent to about 0.0035 percent by weight at use concentration and when the compositions of the invention are used for cleaning and brightening stainless steel, the total concentration of the surfactant component should be from about 0.003 percent to about 0.007 percent, again at use concentration.
• the surfactant component should be present in an amount from about 0.0013 percent to about 0.013 percent.
• their weight ratio should be from about 2.25 to about 1.75 to 1 expressed as primary ethoxylated alcohol/modified polyethoxylated straight chain alcohol, for all three of the applications.
• the sequestrant component of the present invention is made up of a blend of oxalic acid and citric acid.
• the total concentration of the sequestrant component should be from about 0.001 percent to about 0.002 percent by weight, and within these limits, the preferred concentration is from about 0.0012 percent by weight to about 0.0015 percent by weight.
• the concentration of the sequestrant component should be from about 0.006 percent to about 0.0060 percent by weight, and when the compositions are used for reverse roll iron phosphating, the concentration of the sequestrant component should be from about 0.0006 percent to about 0.0060 percent, again by weight.
• the combination of oxalic acid and citric acid appears to produce better results than that of either acid alone. Such improved results are obtained when the ratio of oxalic acid to citric acid is from about 2.25 to 1 to about 1.75 to l, where the oxalic acid is expressed as oxalic acid dihydrate and the citric acid is expressed as anhydrous citric acid.
• the sequestering component serves to increase the aluminum carrying capacity of the solution, and in this connection cooperates with the blend of acids of the acid component discussed above.
• the presence of citric acid in the sequestrant reduces the aluminum surface with satisfactory brightness.
• the oxalic acid represses the corrosion rate of the solution on the stainless steel of the cleaning equipment. While the manner by which it does so is not fully understood, and there is no intention to be bound by a particular theory, it appears that the oxalic acid of the composition forms a very thin protective film on the stainless steel surface and thus reduces the corrosion rate.
• the sequestrant component functions to complex the dissolved oxides forming the scale, and to prevent their redeposition on the metal surface.
• both the oxalic acid and the citric acid contribute to dissolving the required amount of iron from the ferriferous surfaces being treated, and thus increase the ferrous ion concentration at the coating site, so that a uniform phosphate coating will form in the short time available for its formation inherent in the reverse roll ion phosphating method.
• a temperature stabilizer is also included as a component.
• This component serves to stabilize the concentrate when it is subjected to freezing conditions in the course of warehousing or shipping. In addition to lowering the freezing point of the aqueous concentrate, it also retards the formation of precipitates when the concentrate is repeatedly frozen and thawed. Such precipitates are undesirable since they subtract components from the solution nonunifonnly and thus alter the balance of the solution, unless care is taken to bring the precipitates back into dissolved state before use.
• a preferred concentrate in accordance with the present invention has the following formula:
• the percentages of components listed above may be varied somewhat to produce other concentrates, so long as care is taken to maintain the ratios of materials forming each component within the ranges set out above, and to maintain the proportion of each component so that upon dilution to use concentration the above stated concentration ranges are achieved.
• the temperature stabilizing material triethylene glycol
• the temperature stabilizing material may be omitted if expected shipping and storage conditions make it unnecessary.
• the foregoing concentrate is preferably diluted with additional water in a ratio of about 1 part concentrate to about 50 parts water, although good cleaning can be obtained over a dilution of from about 1 to 67 to about 1 to 40, thus producing component ranges as discussed above. Best results are obtained when the diluted solution is heated, and the preferred temperature ranges are from about 185 F., to about 195 F.
• the pH will be from about 1.4 to about 1.5 (measured at room temperature) and in any event it is preferred that the pH be kept well below 2.0. Under these conditions, excellent cleaning of aluminum results; even cans with emulsified drawing oil as one of the soils on the surface, are very satisfactorily cleaned when exposed to a spray of the solution for a suitable time, such as about 60 seconds.
• the above concentrate effectively descales, cleans and brightens stainless steel when it is diluted with water in a ratio of from about 0.01 to 1 to about 0.05 to l.
• the descaling and cleaning is best carried out when the solution is at a temperature of from about F. to about F.
• the length of treatment will depend to some extent upon the degree to which the stainless steel is coated with annealing scale and other soil, but in general, if the solution is contacted with the stainless steel for about 17 to 60 seconds, adequate cleaning and brightening will be obtained.
• the preferred concentrate set forth above can be used to apply an iron phosphate coating to a ferriferous surface by the reverse roll coat method, and when it is so used, it is preferably diluted with water in a ratio of from about 0.03 to l to about 0.05 to 1.
• the surface speed of the reverse roller in such an operation should be between about 51 percent of the speed of the metal surface being coated, and a speed just insufficient, in view of the diameter and rotational velocity of the roller, to cause solution to be thrown from the surface thereof by centrifugal force (usually about 300 percent of the metal surface speed).
• the dwell time of the solution on the surface prior to squeegeeing or wiping should be a minimum of about 5 seconds.
• Table I also illustrates the effect of varying the total between the heater and the cylinder had a thickness of apconcentration of an acid component, as well as the efiect of proximately 1 millimeter.
• This cylinder was placed in two of varying the ratio of sulphuric acid to phosphoric acid. the solutions at a concentration of 1.5 percent and the heater in table 1 below the column headed Cleaning percent H O was used to maintain the solution at 200-2l0 F. for 10 hours. Break reports the degree to which the water breaks, that is, The solution was also vigorously stirred. The penetration was the percentage of the surface area to which a thin continuous calculated from weight loss measurements on the stainless film of rinse water fails to adhere when the surface is cleaned l 5 steel cylinder. A low weight loss represents good performance.
• a low percent water SOIUUORS 1 through 9 of table I h as lhBI' mbreak represents a good cleaning performance by this ponents Surfactant Systems made P of P P f criterion, since discontinuities are caused by residual oily tithoxylated alcohol (Neodol and Percent modified areas which were not removed by the solution during the Polyethoxylated Straight Chain and a cleaning cycle.
• 25 sequestrant component consisting of oxalic acid dehydrate The column headed Smut reports a visual rating of the P and Citric add n y percent The degree of smut left on the an fter bei g l d i th balanceof each of the concentrates employed was water. manner described above.
• the rating scale employed was as Solution 10 ofthe table I had the formula! follows: was,
• Solution is drawn from the bottom of the cylinder and pumped through the spray head at a pres- Formula 11 fTabl 1 i d; sure of 20 psi. and at a selected temperature. After a period, a stable head of foam forms on top of the solution in the cylinder, and it is the height of this foam layer which is reported in table l. A low foam height is desirable.
• Ammonium f p f Technical The column in table I headed Aluminum Dissolution g n ctyl phenoxy polyethoxycthanol 0.8 Rate reports in milligrams per square foot per mtnute the (Triton X402) weight loss of aluminum cans cleaned for one minute at 180 Wr ter 01.9
• the column headed Static Corrosion represents the the sulphuric acid based solution, displays a relatively low alupcnetration, expressed in mils per year, calculated from minum dissolution rate, but it is a relatively poor cleaner with weight loss mcatsurcmcnts made on type 316 stainless steel 70 a high water break and an objectionable amount of smut. ln
• Fonnulas 7, 8 and 9 which represent the preferred ranges and acid ratios for aluminum cleaning, are far superior to prior art formulas l and 1 l with respect to stainless steel corrosion (static and dynamic), are far superior in cleaning ability as measured by smut, are lower foaming, and have acceptable aluminum dissolution rates which are higher than that of formula 11, but lower than that of formula 10. The overall performance of formula 7 was the best.
• Table II below reports a comparison between formula 7 of the invention and prior art solution fonnula 10 with respect to aluminum carrying capacity.
• the surfactant component was omitted from both solutions to prevent it from masking detection of precipitate.
• Aluminum was suspended in 1 9% percent solutions of concentrates 7 and 10 and the solution was heated to 200 F. by an electric heater with a stainless steel jacket. The heater was frequently partially removed from the test bath and inspected to determine the point at which precipitation in the form of scale started to appear on the stainless steel jacket, and the aluminum concentration was measured when such precipitation first occurred.
• Table II shows, the aluminum carrying capacity in grams/liter of formula 7 was nearly three times that of formula 10.
• compositions of the present invention for cleaning, deoxidizing, and brightening stainless steel is illustrated by the following example:
• the preferred concentrate was used tion.
• compositions of great versatility are provided for use in treating metal surfaces.
• a concentrated composition suitable, upon dilution with water, for cleaning of aluminum surfaces, for deoxidizing and cleaning of stainless steel, and for forming an iron phosphate coating on ferriferous surfaces comprising an aqueous solution of:
• an acid component consisting of sulfuric acid and phosphoric acid in a volume ratio of from about 0.5 to 1 to about 1.5 to 1, (calculated as 66 B. sulfuric acid/75 percent phosphoric acid);
• a sequestrant component consisting of oxalic acid and to form 5 percent solucitric acid in a weight ratio of from about 2.25 to l to about 1.75 to 1 (calculated as oxalic acid dihydrate/anhydrous citric acid);
• the components being present in the concentrate in amounts sufficient, upon dilution of the concentrate with water, to produce a solution for cleaning aluminum in which the concentration of the acid component is between about 0.001 percent and about 0.005 percent by weight, the concentration of the surfactant component is between about 0.0010 percent and about 0.0035 percent by weight, and the concentration of the sequestrant component is between about 0.001 percent and 0.002 percent by weight, and to produce a solution for cleaning and deoxidizing stainless steel in which the concentration of the acid component is between about 0.003 percent and about 0.015 percent by weight, the concentration of the surfactant component is between about 0.003 percent and about 0.007 percent by weight, and concentration of the sequestrant component is between about 0.0006 percent and about 0.0060 percent by weight, and further to produce an iron phosphating solution in which the concentration of the acid component is between about 0.0015 percent and about 0.015 percent by weight, the concentration of the surfactant component is between about 0.0013 percent and about 0.013 percent by weight, and the concentration of the sequestrant
• composition according to claim 1 in which said surfactant component consists of primary ethoxylated alcohol and modified polyethoxylated straight chain alcohol.
• composition according to claim 3 in which the weight ratio of primary ethoxylated to modified polyethoxylated straight chain alcohol is between about 2.25 to 1 to about 1 .75 to 1.
• a concentrate useful upon dilution with water for treatment of metal surfaces consisting essentially of an aqueous solution containing about 11 percent by weight phosphoric acid (calculated as 75 percent phosphoric acid), about 12.8 percent by weight sulfuric acid (calculated as 66 B. sulfuric acid), about 8.0 percent by weight primary ethoxylated alcohol, about 4.6 percent modified polyethoxylated straight chain alcohol, about 2.0 percent by weight oxalic acid (calculated as oxalic acid dihydrate) and about 4.2 percent by weight citric acid (calculated as anhydrous citric acid).
• a solution for cleaning aluminum surfaces comprising an aqueous solution consisting essentially of:
• an acid component consisting of sulfuric acid and phosphoric acid in a volume ratio of from about 0.5 to 1 to about 1.5 to 1, (calculated as 66 B. sulfuric acid/75 percent phosphoric acid), the concentration of said acid component being between about 0.001 percent and about 0.005 percent by weight,
• a surfactant component in an amount between about 0.0010 percent and 0.0035 percent by weight
• a sequestrant component consisting of oxalic acid and citric acid in a weight ratio of from about 2.25 to l to about 1.75 to 1 (calculated as oxalic acid dihydrate/anhydrous citric acid), the concentration of said sequestrant component being between about 0.001 percent and about 0.002 percent by weight.
• a solution for cleaning deoxidizing and brightening stainless steel comprising an aqueous solution consisting essentially of:
• an acid component consisting of sulfuric acid and phosphoric acid in a volume ratio of from about 0.5 to l to about 1.5 to 1, (calculated as 66 B. sulfuric acid/75 percent phosphoric acid), the concentration of said acid component being between about 0.003 percent and about 0.015 percent by weight,
• a surfactant component in an amount between about 0.003
• a solution for applying an iron phosphate coating to ferriferous surfaces comprising an aqueous solution consisting essentially of:
• an acid component consisting of sulfuric acid and phosphoric acid in a volume ratio of from about 0.5 to l to about 1.5 to 1, (calculated as 66 B. sulfuric acid/75 percent phosphoric acid), the concentration of said acid component being between about 0.0015 percent and about 0.015 percent by weight,
• a surfactant component in an amount between about 0.0013 percent and about 0.013 percent by weight
• a sequestrant component consisting of oxalic acid and citric acid in a weight ratio of from about 2.25 to l to about 1.75 to 1 (calculated as oxalic acid dihydrate/anhydrous citric acid), the concentration of said sequestrant component being between about 0.0006 percent and about 0.0060 percent by weight.
• surfactant component consists of primary ethoxylated alcohol and modified polyethoxylated straight chain alcohol in a ratio of from about 2.25 to l to about 1.75 to 1.
• a method for cleaning aluminum surfaces comprising contacting said surfaces with an aqueous solution consisting essentially of:
• an acid component consisting of sulfuric acid and phosphoric acid in a volume of from about 0.5 to l to about 1.5 to 1, (calculated as 66 B. sulfuric acid/75 percent phosphoric acid), the concentration of said acid component being between about 0.001 percent and about 0.005 percent by weight,
• a surfactant component in an amount between about 0.0010 percent and about 0.0035 percent by weight
• a sequestrant component consisting of oxalic acid and citric acid in a weight ratio of from about 2.25 to 1 to about 1.75 to 1, (calculated as oxalic acid dihydrate/anhydrous citric acid), the concentration of said sequestrant component being between about 0.001 percent and about 0.002 percent by weight, and thereafter rinsing said surfaces.
• a method for cleaning deoxidizing and brightening stainless steel surfaces comprising contacting said surfaces with an aqueous solution consisting essentially of:
• an acid component consisting of sulfuric acid and phosphoric acid in a volume ratio of from about 0.5 to l to about 1.5 to 1, (calculated as 66 B. sulfuric acid/75 percent phosphoric acid), the concentration of said acid component being between about 0.003 percent and about 0.0015 percent by weight,
• a surfactant component in an amount between about 0.003
• a method for applying an iron phosphate coating to ferriferous surfaces comprising applying by a reverse contact roll to a moving ferriferous surface and an aqueous solution consisting essentially of:
• an acid component consisting of sulfuric acid and phosphoric acid in a volume ratio of from about 0.5 to l to about 1.5 to 1, (calculated as 66 B. sulfuric acid/75 percent phosphoric acid), the concentration of said acid component being between about 0.0015 percent and about 0.015 percent by weight,
• a surfactant component in an amount between about 0.0013 percent and about 0.013 percent by weight
• a sequestrant component consisting of oxalic acid and citric acid in a weight ratio of from about 2.25 to l to about 1.75 to 1, (calculated as oxalic acid dihydrate/ anhydrous citric acid), the concentration of said sequestrant component being between about 0.0006 percent and about 0.0060 percent by weight, and allowing said solution to dwell on said surface for at least 5 seconds.
• Claim 19 line 9 "0.0015”, should read --0 .015.

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• Chemical & Material Sciences (AREA)
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• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Chemical Treatment Of Metals (AREA)

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• 1969
  • 1969-11-03 US US873626A patent/US3635826A/en not_active Expired - Lifetime
• 1970
  • 1970-03-31 CA CA078743A patent/CA929447A/en not_active Expired
  • 1970-11-02 JP JP45096803A patent/JPS5021147B1/ja active Pending
  • 1970-11-03 DE DE2054067A patent/DE2054067C3/de not_active Expired

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