AU2003200427B2 - No-rinse method for repairing coated surfaces - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: NO-RINSE METHOD FOR REPAIRING COATED SURFACES The following statement is a full description of this invention, including the best method of performing it known to us NO-RINSE METHOD FOR REPAIRING COATED SURFACES BACKGROUND OF THE INVENTION RELATED APPLICATION This application is a divisional of Australian Patent Application No.

46425/96, the contents of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION This invention relates to a no-rinse method for repairing a damaged coating on a metal surface.

DESCRIPTION OF THE PRIOR ART In industrial use, there are many methods of applying flowable material compositions to surfaces and many types of applicators for this purpose. Among such methods, there are spraying systems and pumping systems, immersion baths and the like. As well, different types of applicators include fibrous markers, felt tip pens, capillary tube pens and the like.

Continuing efforts have been made in the past to improve the safety of such items when the flowable material is of a hazardous, toxic, or offensive nature. Particularly, in the field of metal coating and treating, such efforts have involved developing systems where the user is physically removed from the article to be treated or coated by employing such devices as spray-booths and immersion baths. A major drawback of such a system is that minor defects in the coating or treatment are difficult to repair and require that the entire article be completely reimmersed or recoated. This process can be particularly time consuming and expensive, since a small defect in the coating will require the expenditure of enough chemical or flowable material to re-treat the entire article.

Typically, aluminum or other metal parts for use in commercial and military systems are fabricated, and then their surfaces are chemically treated to prevent corrosion, using conventional batch processing techniques. This chemical treatment process is quite important in applications that require electrical and thermal insulation or conductivity, for example. After chemical treatment, however, many parts become scratched during subsequent handling or processing steps, which remove a portion of the chemically treated corrosion protection layer from the surface of the parts. Consequently, it becomes necessary to treat the scratched areas to return the surfaces to a condition of complete chemically treated corrosive protection.

The conventional method of repairing the scratched surface is to obtain a bottle of coating solution, and then using cotton balls, Q-tips, rags, or sponges, and the like, rub or otherwise apply the composition or coating solution over the scratched areas until the scratch is fully coated. In many cases, the shape of the parts creates many problems in applying the coating solution to the surface.

The coating solution may be and often is a corrosive, hazardous material, since it may contain, for example, quantities of chromic acid, fluoride, ferricyanide, and ferrocyanide. Conventional procedures typically apply excessive quantities of the coating solution, and often result in spillage, creating a hazardous condition in the treatment area. The conventional process is messy, and much of the coating solution is wasted. The cotton balls, Q-tips, rags, or sponges, and the like which are used to apply the coating solution or to clean it up, become hazardous waste as a result of their use and thus present disposal problems.

Generally the coating solutions or flowable materials are of two types: those that require rinsing to remove excess coating material, and those that do not require rinsing. The former may require rinsing because they tend to form crystals that produce an undesirable surface roughness and present a hazard because these crystals, as well as any residual coating, are generally highly active, pH 1.5-4.5. Rinsing is necessary but creates rinse water that is corrosive because it is acidic, and may be toxic as well, and this poses a disposal problem. No-rinse (NR) coating materials do not form crystals, can be formulated to be self-levelling, and do not require rinsing for those reasons.

Prior to the advent of the present invention, industrial users of metal treating and coating technologies were unable quickly and efficiently to correct minor defects in a coating or treatment of a metal surface because the nature of the chemicals used to treat and coat metal surfaces makes them difficult to use safely by a person because of the risk of exposure of the person to the chemical.

As well, devices for safely handling and storing such small quantities of offensive chemicals were simply unavailable to the industry.

Accordingly, it is an objective of the present invention to provide industry with a no-rinse coating method that eliminates the above-mentioned problems.

Another objective of the present invention is to provide for an environmentally safe method to safely and efficiently assist with touch up and repair of scratched or otherwise damaged metal surfaces with hazardous, toxic, corrosive, or otherwise offensive chemical solutions. Such compositions may be conversion coating compositions for treating steel and galvanized steel, for example, acidic zinc and other iron phosphate compositions.

Further, the invention provides industry with a method safely and efficiently to assist in the coating of a surface.

Further, the present invention also provides the metal treatment industry with an improved no-rinse method of repairing minor defects that occur in metal coatings and treatments and hence reduces the high costs associated with having to recoat and retreat metal articles.

The foregoing has outlined some of the uses and advantages of the present invention. These uses and advantages should be construed to be merely illustrative of some of the more pertinent features and applications of the invention.

Accordingly, other aspects and advantages, and a fuller understanding of the invention, may be had by referring to the Summary of the Invention and to the Detailed Description describing some of the preferred embodiments in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying Drawings.

SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, there is provided a no-rinse method for repairing a damaged coating on a metal surface, which includes applying to a metal surface having a damaged coating thereon, over said damaged coating area, a layer of a no-rinse composition which includes a mixture of chromium compounds, a water-soluble solution including polyacrylic acid and/or esters thereof, and water; and allowing said layer to dry in place as applied, without rinsing.

The composition may be a flowable material that can be dispensed by an applicator for metal treating and coating, and especially for the conversion coating of aluminum surfaces, the applicator is charged with a flowable material suitable for preventing corrosion of the metal surface. Alternately, a material suitable for treating a metal surface prior to subjecting the metal surface to a coating process may be desired. For these purposes, it is preferred to charge the applicator with one of the following: a non-accelerated chromium chromate composition in an aqueous acidic solution; a chromium chromate composition in an aqueous acidic solution accelerated, preferably with ferricyanide, ferrocyanide, or molybdate; or a chromium phosphate composition in an aqueous acidic solution; or a zirconium phosphate composition depending on the nature of the treatment. As well, the applicator can be charged with a composition such as an acidic zinc phosphate solution for use in coating cold-rolled steel or galvanized steel.

The coating composition for forming an aqueous liquid conversion coating on a metal surface, may include in admixture an aqueous solution of an acidic conversion coating solution having a pH below about 4.5, and a functionally effective amount of an acid-stable fluorochemical surfactant to improve the flowability of said coating.

In further embodiments of the invention for use in metal treating and coating, any of the previously identified chromate compositions is mixed with a fluorinated-type surfactant (such as a Fluorad® surfactant) to improve the flow and coating properties of the metal treatment composition. Fluorad® surfactants are preferred as it has been found that they are highly stable in an acidic environment containing chromates. "Fluorad" is the trademark of the Industrial Chemical Products Division of Texaco Chemical Co., for its line of fluorochemical surfactants.

The method of the present invention in one embodiment employs an applicator that uses a felt tip or analogous marker containing a coating solution or other appropriate chemical solution of the kind above described. The applicator and solution are used to touch up small areas and or scratches on treated metal surfaces. The method of the present invention may eliminate the hazardous waste normally produced in the touch up process, and substantially reduces the number of process steps and time involved.

The method of the present invention may be used to treat aluminum, and other metals. The present method may be employed in pre-paint processes in the automotive, marine, aircraft, coil coating and general industries.

The foregoing has outlined the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood, so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing one embodiment of an applicator employed with a method in accordance with the invention, with a guard disk projecting radially outward from the cylindrical body of the applicator, and with its end cap detached from the proximal end of the applicator and spaced below the applicator tip; FIG 2 is a perspective view similar to Figure 1 showing also a closure end cap for a distal end of the application; FIG 3 is a side elevation view partially in section of an application similar to Figure 2; FIG. 4 is a side elevation, partly in vertical section, showing another, similar embodiment of an applicator employed with a method in accordance with the invention, with the upper end cap integrally molded to the distal end of the applicator; FIG. 5 is a side elevation, partly in vertical section, showing another embodiment of an applicator employed with a method in accordance with the invention, showing a spring biasing the sealing member into the discharge port, thereby preventing discharge of flowable material; FIG. 6 is a side elevation, partly in vertical section, showing another embodiment of the applicator employed with a method in accordance with the invention, showing that an upward force exerted on the wick presses the sealing member out of the discharge port and allows flowable material to be discharged from the applicator; FIG. 6a is a side elevation, partly in vertical section, of another embodiment of the applicator employed with a method in accordance with the invention, showing a horizontal member within the chamber, against which the spring is biased; FIG. 6b is a cross-sectional view of the chamber of the applicator of Figure 4a, showing the horizontal member disposed above the sealing member; FIG. 7 is a top plan view on an enlarged scale, showing the upper end of a different embodiment of the applicator employed with a method of the present invention, showing the guard disk as a solid but transparent disk; FIG. 8 is a top plan view on the same scale as FIG. 7, showing the upper end of still another embodiment of the applicator employed with a method, of the present invention showing the guard structure as a circular ring which is connected to the cylindrical body of the applicator by four spokes that extend radially from the cylindrical body of the applicator; FIG. 9 is a top plan view on the same scale as FIG. 7, showing the upper end of another embodiment of the applicator employed with a method of the present invention, showing the guard structure as light, radially-extending spokes; FIG. 10 is a perspective view of a rack for applicators employed with a method of the present invention, showing a single cavity, with an applicator inserted into a perimetral recess, and with the guard collar resting on a surface about a recess; FIG. 11 is a side view of another embodiment of a rack, showing a plurality of cavities formed adjacent the perimeter of the cylindrical housing, each holding or being adapted to hold an applicator employing a composition used in a method in accordance with the present invention; FIG. 12 is a sectional view of another embodiment of the rack of the present invention, showing a plurality of cylindrical cavities formed in the cylindrical housing, with a cavity holding an applicator employing a composition used in a method in accordance with the present invention; FIGS. 13 and 14 are side views of further possible embodiments of the housing including applicators position thereon.

DETAILED DESCRIPTION OF THE INVENTION Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term "about." All amounts and percentages are by weight unless expressly stated to be otherwise, and all temperatures are degrees Celsius unless otherwise stated.

Referring now in detail to the drawings by numerals of reference, where similar reference numerals refer to similar parts throughout, an applicator 100 employed using the composition and method of the present invention, as shown in FIGS. 1 to 3, comprises a generally cylindrical housing 2 having therein a chamber 4. The housing 2 includes a distal end 24 having an aperture 14 which provides communication between the chamber and the outside of the housing, allowing flowable materials to be introduced into the chamber through said aperture. The housing 2 also includes a proximal end 24 having a discharge opening 14 through which flowable materials can be dispensed.

In order to make the housing 2 durable, easy to construct, and inexpensive, many types of plastic are suitable materials of construction. It is, therefore, preferred that each component of the present invention be manufactured from plastic, unless otherwise specified. Further, the housing 2 may be labelled or printed with indicia which identifies the flowable materials within the chamber 4 or any hazards associated with it.

The applicator 100 includes a wick 12 projecting through the discharge port 14 of the proximal end 22 for dispensing flowable materials through the discharge. Preferably, the wick 12 comprises a foraminous material such as polyester or polyethylene which will conduct flowable material from the chamber 4 onto the surface to be treated. An end cap 10 is shown that is releasably attachable to the proximal end 22. To avoid accidental misplacement of the end cap 10, an optional retainer strap 16 may be connected at its distal end 17 to the end cap 10 and at its proximal end 19 to the housing 2. The end cap 10 is shown in FIG. 1 as having a latch 13 of the type known in the art, to prevent accidental removal of the end cap 10. Also shown is an end cap 8 which releasably attaches to the distal end 24 of the housing 2. The end cap 8 is also shown having a latch 18 of the type known in the art, to prevent accidental removal of the end cap 8. The safety collar 6 is a solid disk and is shown projecting from the applicator housing 2.

The safety collar 6 is preferably molded as part of the housing 2 during the fabrication of the housing 2, or the safety collar 6 can be fabricated separately and permanently adhered to the housing 2 by means of adhesives known in the art or by fusing the collar 6 and the housing 2 together using heat. Additionally, the collar 6 may be slidably mounted on the housing 2, by means of a loose friction-fit. Further, although the safety collar 6 may be fabricated from any desired material, it is preferred that it be made of transparent material, such as clear plastic, to enable the user to easily see the point of contact between the applicator and the surface to be treated.

FIG. 4 shows the end cap 20 may be permanently attached to the distal end 24 of the housing 2. In this embodiment, the applicator is not refillable, as the chamber 4 is filled by the manufacturer and permanently sealed. This embodiment avoids the possibility of accidental leakage of flowable material from the applicator.

In FIGS. 5 and 6 show a valve 29 is disposed within the chamber 4. The valve 29 includes a spring 28 which biases a sealing member 30 whereby the sealing member 30 engages and closes the discharge opening 14 of the proximal end 22 and thereby prevents communication between the chamber 4 and the exterior of the housing 2. For simplicity and economy, it is preferred that the spring is manufactured from metal.

FIG. 5 illustrates the valve 29 in a closed position. When no force is exerted against the wick 12, the spring 28 biases the sealing member 30 into the discharge opening 14 and prevents communication between the chamber 4 and the outside of the housing 2, and thus preventing the discharge of flowable material.

As shown in FIG. 6, when pressure is exerted against the wick 12, the sealing member 30 disengages and opens the discharge opening 14 of the proximal end 22 allowing communication between the chamber 4 and the exterior of the housing 2 and thereby enabling the dispensing of flowable materials through the discharge opening 14 of the second end 22. The valve 29 shown in FIGS. 5 and 6 is simple and inexpensive to construct.

However, it may be desirable to employ commercially available valves under certain circumstances, such as when using more hazardous chemicals which require more extensive safeguards against leaks. Valves suitable for use in the present invention are described in U.S. Pat. Nos. 4,848,947, 4,792,252, and 4,685,820, each of which is expressly incorporated herein by reference.

FIGS. 7-9 show alternate embodiments of the safety collar 6. FIG. 7 illustrates the safety collar 6 as a solid disk of transparent material, such as clear plastic, attached to the periphery of the housing 2. FIG. 8 illustrates the projecting structure, or safety collar 6, as a circular ring 40 which attaches to the periphery of the housing 2 by a number of connector rods 42. FIG. 7 illustrates the projecting structure or safety collar 6 as a plurality of spokes 26 emanating from said housing 2. FIGS. 7-9 each illustrate a projecting structure 6 which deters the user of the applicator from inserting the applicator 300, 500, 600 into a garment pocket, such as a shirt pocket, jacket pocket, pants pocket, etc., or other inappropriate receptacle such as a desk drawer, tool box, etc. By so inhibiting the placement or insertion of the applicator into such places, the risk is reduced of accidental exposure to the flowable material contained in the applicator, whether it is of a hazardous nature or not.

FIG. 10 is a perspective view of a rack 60 for storing, transporting, and dispensing applicators 100 in large quantities (only one applicator being shown in FIG. 8, for simplicity). The rack 60 comprises a single, molded housing 52 having a plurality of cylindrical cavities 54 formed adjacent the perimeter of the housing 52.

The housing 52 may be cylindrical, as shown in FIG. 10 or it may be rectangular FIG. 12 shows a top plan view of the rack 60, with an applicator 100 disposed within a cavity 54. FIG. 11 shows an alternate embodiment of the rack of the present invention. In FIG. 11, rack 70 is formed with a plurality of cylindrical cavities 54 in its top surface 72, each cylindrical cavity 54 being of a sufficient depth and diameter to hold an applicator 100.

A method of applying flowable materials comprises introducing flowable material into the chamber 4 of applicator 100, providing a clean surface onto which flowable material is to be applied, and contacting the surface with the wick 12 of the applicator 100.

A more preferred method further comprises providing an applicator 100 having the valve 24 within the chamber 4 of the applicator 100, with a wick 12 projecting through the discharge opening 14 of the proximal end 22 of the applicator 100, introducing a flowable material into chamber 4 of applicator 100, contacting the surface onto which flowable material is to be applied with the wick 12, and pressing the wick onto that surface, causing the valve 29 to open so the flowable material is discharged from the applicator 100 onto the surface.

In a preferred method, the flowable material introduced into the chamber 4 of the applicator 100 is a non-accelerated aqueous acidic chromium chromate composition. Such a composition does not contain ferricyanide, ferrocyanide, or molybdate. A preferred composition of this nature is described in U.S. Pat. No.

2,851,385, which is expressly incorporated herein by reference.

It has been found to be beneficial to add, in accordance with the present invention, an acid-stable surfactant, to the aqueous, acidic conversion coating compositions described in the following Examples to facilitate flow and to act as a levelling agent. Generally, the fluorinated surfactants are stable in highly acidic conditions, and the fluorinated surfactants sold under the trademark Fluorad® surfactants are preferred.

The applicator preferably is made of some inert plastic material that can withstand the corrosive nature of the acidic conversion compositions. Generally the lowest useful pH for such compositions is about 1.5. However, it is preferred that the conversion compositions used with the applicator have a pH of less than or more preferably, a pH in the range from 1.5 to The applicator is particularly useful in the repair of phosphate conversion coatings used on cold-rolled steel or galvanized steel. Such coating compositions generally are based on phosphate salts, such as those of zinc, manganese, or nickel dihydrogen phosphate, with either bound or unbound fluorine. Such conversion coating compositions also preferably are modified by the addition of an acid stable surfactant, such as a fluorinated surfactant.

Conversion coating compositions may also be made using mixtures of the salts, and are also useful in the applicators of this invention.

Such conversion coating compositions can be accelerated by the addition of one or more of hydroxylamine sulfate or sodium nitrite. For example, such compositions based on the use of zinc phosphate, manganese phosphate, or mixtures of these, can be accelerated in this way, and are particularly useful for automobile body coatings. Generally, such coatings also benefit from the addition of an acid-stable surfactant.

Exemplary conversion compositions used in the automotive industry, particularly on galvanized or cold-rolled steel, are those disclosed in the Miyamoto and Nagatani patents, specifically U.S. Pat. No. 4,838,957, issued Jun. 13, 1989, and U.S. Pat. No. 4,961,794, issued Oct. 9, 1990. These patents are specifically incorporated herein by reference, for their disclosure of conversion compositions and processes for treating galvanized metal surfaces.

The compositions and processes of these patents are used in a great majority of the automotive production lines in the United States.

This invention is also particularly useful in preparing aluminum surfaces, such as those on aircraft skins and aircraft parts, aluminum extrusions such as coils, aluminum storm doors, and the like.

Generally, there are two distinct kinds of metal treating solutions, those that require rinsing, and those that do not. Since many of the components of conversion coating compositions are characterized by toxicity and/or high acidity, the compositions that require rinsing may generate wastewater that must be collected and that, with the present federal regulations, present a disposal problem.

For treating aluminum surfaces, among the useful conversion coating compositions are those comprising mixtures of polyacrylic acid and/or esters thereof, and a second ingredient consisting essentially of chromium chromate.

Such a solution will not form crystals. Such compositions therefore do not require rinsing and therefore do not create a wastewater disposal problem. After application to a surface in need of repair, by the applicator, the applied coating composition is simply allowed to dry in place, or force dried.

Generally, for all coating compositions that require rinsing, the addition of a fluorinated surfactant is beneficial, leading to improved performance. For those formulations that do not require rinsing, they may be used with or without the addition of a fluorinated surfactant, but the addition of a fluorinated surfactant generally is beneficial. In addition to improving flow from the applicator and improving levelling characteristics of the composition, the presence of the acidstable surfactant tends to improve the flow of the coating composition into scratches in a finish that is being repaired. Generally, the amount of fluorinated surfactant that is useful is in the range from 0.001% to 0.02%, by weight, based on the overall weight of the composition. Amounts in the range from 0.001% to 0.05% can be used, or even larger quantities, but the larger quantities are not cost effective.

The fluorinated surfactants are available from several sources, generally under different trademarks. The following are exemplary of fluorinated surfactants that are useful in the coating compositions that can be used with the applicator. Generally, these are aqueous compositions that are readily compatible with the conversion coating compositions described in the following Examples.

Fluorinated Surfactant Materials Fluorad FC-126 (3M) Fluorad FC-430 Fluorad FC-120 Zonyl FSN (Dupont) 85% Ammonium Perfluorooctanoate (CAS# 3825-26-1) of Lower Perfluoroalkyl Carboxylate Salt (CAS# 6130-43-4, 21615-4, 68259-11-0) Fluorinated alkyl ester 25% Ammonium Perfluoroalkyl Sulfonate (CAS# 67906-42-7 17202-41-4) 40% Perfluoroalkyl Ethoxylate

IPA

Water 50% Fluorophosphoric acid 50% Fluorophosphonic acid Fluowet PL 80 (Hoechst-Celanese) The following example, and other subsequent examples, demonstrate some of the types of solutions that may be used in the practice of the present invention.

Conversion Coating for Aluminium Its Alloys EXAMPLE 1 Chromic acid 6 grams Potassium zirconium fluoride 2.5 grams Ammonium borofluoride 7.6 grams Water to make 1 litre 24ST aluminum alloy sheets which is treated in a solution similar to the above formulation has satisfactorily withstood a salt fog exposure in a standard sodium chloride ASTM Salt Fog Cabinet for over 500 hours with only minor pinpoint corrosion.

A scratch in the treated sheet is easily and conveniently repaired by filling the chamber of an applicator such as is shown in FIG. 1, with some of the solution described above, then applying it over the scratched surface by using the wick 14 of the applicator. After water rinsing and drying, the coating is as good as new.

The following non-accelerated solutions can also be used as conversion coatings for aluminum and its alloys, and all can be conveniently applied for touchup of scratches using an applicator of the present invention.

EXAMPLE 2 Chromic acid 8.4 grams Potassium zirconium fluoride 3.5 grams Boric acid 6.3 grams Ammonium bifluoride 4.0 grams Water to make 1 litre EXAMPLE 3 Chromic acid 8 grams Hydrofluoric acid 2.0 ml of 48% acid EXAMPLE 4 Ammonium bifluoride 2.7 grams Chromic acid 6.0 grams

H

2 SnF 6 (Fluostannic acid) 3.5 grams Water to make 1 litre The scratched area should be cleaned before the applicator is used to restore the surface by applying a restorative solution or coating. The cleaning, which forms no part of the present invention, may be carried out by conventional methods. For instance, grease and dirt may be removed by dipping an aluminum part into a mild silicate alkali bath or by the use of an acid bath containing a polar organic solvent, followed by a water rinse. The clean scratched area may then be treated with a solution of the character described, such as the solutions of the above Examples.

In another preferred method of applying flowable materials, the flowable material introduced into the chamber 4 of the applicator 100 is an accelerated aqueous acidic chromium chromate composition. An accelerated aqueous acidic chromium chromate composition contains ferricyanide, ferrocyanide or molybdate.

Compositions of this nature are particularly useful for the process of metal cleaning and improving corrosion resistance. Preferred compositions of this nature are described in U.S. Pat. No. 2,796,370, describing a useful ferricyanide accelerated chromium chromate composition, and U.S. Pat. No. 4,146,410, describing a useful molybdate accelerated chromium chromate composition, which patents are expressly incorporated herein by reference.

The coatings applied in the following examples exhibit enhanced corrosion resistance. Scratches that expose the same metal surface can readily be repaired by using the methods and applications of this invention.

EXAMPLE Use of Accelerated Chromate Coatings; Ferricyanide Chromic acid g./I Potassium ferricyanide g./l Sodium fluosilicate g./I Sodium fluoborate g./l Temperature °F Immersion time 5 minutes pH The general temperature range of 320 to 1600 F. is applicable to the above composition. A temperature range of 700 F. to 900 F. is preferred. The application time can vary from five seconds to about five minutes or over, depending upon the color or thickness of coating desired.

EXAMPLE 6 Use of Accelerated Chromate Coatings; Paint Receptivity In this preferred embodiment, a concentrate is prepared utilizing commercially available materials, by combining the materials in water to form the concentrate. The concentrate is prepared from the following ingredients in the amounts specified: Material Grams/liter CrO3 40.0 g.

ZnO 7.6 g.

HNO3 38 B6 68.0 g.

H

2 SiF 6 as a 23% solution 91.2 g.

Molybdic acid as 84% MoO 3 9.5 g.

Water balance From this concentrate a bath is prepared by diluting the concentrate with water to make a 5% (by volume) solution. The final solution pH is about A five stage commercial aluminum coil coating line consisting of four immersion tanks followed by a fresh water spray final rinse is made operational.

The line speed is adjusted to vary to between no more than about 25 to 100 feet per minute. Utilizing this set-up aluminum coil stock of various alloy compositions, including the type commonly known as 3003, 3105, 5005, 5052 and "utility stock" is treated as follows.

The coil line is started and the coil is first cleaned in both stages 1 and 2 by immersion in an acidic metal cleaning solution, as is well known in the art and which forms no part of this invention. Following the two cleaning stages, the coil is processed in stage 3, which is an immersion water rinse stage. The clean coil then proceeds to stage 4 where it is contacted, by immersion, with the above described bath solution for various time periods of from about 10 to about 30 seconds. The pH of the bath solution is maintained at about 1.5 and the bath temperature is kept at approximately 1200 F. Following treatment with the composition of this invention, the aluminum coil is subjected to a final water spray rinse after which the metal is dried and painted.

Analysis of the appearance and properties of metal treated in the above fashion indicates that the final product is in all ways comparable to metal produced by prior art ferricyanide containing processes. Mechanical damage to the surface of the coated aluminum alloy stock is readily repaired by the use of the immersion solution in a applicator, according to the present invention.

In another preferred method, the flowable material introduced into the chamber 4 of the applicator 100 is an aqueous acidic chromium phosphate composition. Compositions of this nature are particularly useful for the process of metal cleaning and improving corrosion resistance. A preferred composition of this nature is described in U.S. Pat. No. 2,438,877, which is expressly incorporated herein by reference.

The use of a highly corrosive bath for imparting corrosion resistance to aluminum and aluminum alloys, where aluminum is the principal ingredient, is illustrated by the use of baths containing ions of phosphate, fluoride, and hexavalent chromium, at a low pH, often referred to as chrome phosphate compositions.

The solutions described in the preceding two paragraphs can readily be used in touch up work using the hand-held applicator of the invention. Since these solutions are corrosive, the applicator, when made of inert plastic material, is a convenient place for storing a small amount of solution when the applicator is not in use. The guard structure protects clothing and helps ensure that a filled applicator is properly stored.

EXAMPLE 7 An illustrative chrome phosphate bath may contain, where the ions are present in amounts stoichiometrically equivalent to: Grams per liter Fluoride 2.0 to Chromic acid (Cr0 3 6.0 to 20.0 Phosphate (P0 4 20.0 to 100.0 pH 1.7 to 1.9 The ratio of fluoride to dichromate, expressed as Fe:CrO 3 is between 0.18 and 0.36.

All of the foregoing coating compositions require rinsing, for good results.

No-Rinse Compositions EXAMPLE 8 No-Rinse Treatments With A Chromate Conversion Coating CHROMIUM by wt.

Mixed Chromium compounds Acrysol A-i, a water soluble of polyacrylic acid 0.5 The mixed chromium compounds are prepared in accordance with U.S.

Pat. No. 3,063,877, which is incorporated herein by reference. This composition can be used in an applicator on all metals for repairing damaged conversion coatings. No rinsing is required; the coating is simply permitted to dry, or it can be force dried at 1500 F. or higher. As with essentially all of the conversion coatings, adequate ventilation should be provided when these coatings are being poured, used, and dried. Operators should avoid inhaling the vapors. If an air stream is used to promote drying, its velocity should be limited to 3,000 fpm or less, to avoid disruption of the film.

EXAMPLE 9 Non-Chromate Acidic Aqueous Composition A typical five percent operational bath made up from a concentrate using deionized or distilled water may contain the essential ingredients in the amounts indicated below: polacrylic acid (added as ACRYSOL A-1) 4.13 grams/liter

H

2 TiF 2.0 grams/liter EXAMPLE In another preferred method of applying flowable materials, the flowable material introduced into the chamber 4 of the applicator 100 is a zinc phosphate composition. Such compositions are most useful for coating cold-rolled steel and galvanized metals. A preferred composition of this nature is described in U.S. Pat.

No. 2,438,957, which is expressly incorporated herein by reference.

EXAMPLE 11 Comparison Example: Controls, Conversion Coatings, and No-Rinse Coatings Damaged Surface Repair Regimens and Panel Testing Results To illustrate the efficacy of the applicator for repairing damaged aluminium surfaces, laboratory panel testing was performed. Each test started with a panel of 3" by 10" 2024 aluminium which had been previously treated with chromate conversion coating sold under the tradename Alodine) 1200S, by the Henkel Corporation of Gulph Mills, Pennsylvania.

Each panel then had a 2-1/2" by 2" area sanded to remove the conversion coating, and three areas were scratched with a sharp blade. The damaged areas were then cleaned, rinsed, and dried.

Each damaged area was then repaired using the applicator of the present invention having a conversion coating introduced into the chamber 4 of the applicator 100. The contents of the chamber 4 used in each test are listed under the Chemical column of the following table of results. In tests that included a fluorinated surfactant in the conversion coating, the concentration of the fluorinated surfactant was by volume, of the coating solution.

The testing was then performed in accordance with the procedures listed below, under the Treatment column of the following table of results. After repairing the damaged surface by contacting the damaged portion of the panel with the wick 12 of the applicator 100 to completely cover the damaged area with the applied conversion coating, the panel was then subjected to a 168 hour salt spray to determine whether use of the applicator had sufficiently repaired the surface. In order to pass the repair test, the surface must have been free from corrosion and defects after the salt spray. The results of the repair testings are indicated with each procedure, under the column labelled Results.

Test #1 Test #1 used a chromate conversion coating sold under the trademark Alodine® 1201, by the Henkel Corporation of Gulph Mills, Pennsylvania.

Chemical Treatment Result Control No Treatment Corroded Alodine® 1201 applied, 3 min. dwell, Pass Conversion then rinse coating Alodine® 1201 applied, 5 min. dwell, Pass Conversion then wet rag wipe coating Alodine® 1201 applied and rinsed Pass Conversion coating with fluorinated surfactant Alodine® 1201 applied, 5 min. dwell, Pass Conversion coating with fluorinated surfactant then wet rag wipe Alodine® 1201 Conversion coating with fluorinated surfactant applied, 10 min. dwell, rinsed, dried Pass Test #2 Test #2 used Alodine® 1001 chromate conversion coating, sold by the Henkel Corporation of Gulph Mills, Pennsylvania.

Chemical Treatment Result Control No Treatment Corroded Alodine® 1001 Conversion coating Alodine® 1001 Conversion coating applied, 5 min. dwell, then rinse applied, 24 hr.. dry, then wet rag wipe applied, then rinse Pass Pass Alodine® 1001 Conversion coating with fluorinated surfactant Alodine® 1001 Conversion coating with fluorinated surfactant Alodine® 1001 Conversion coating with fluorinated surfactant Pass applied, then wet rag wipe Pass applied, air dried then wet rag wipe Pass Test #3 Test #3 used a no-rinse Bonderite® 1402W chrom-containing coating sold by the Henkel Corporation of Gulph Mills, Pennsylvania. The coating was diluted by adding 9 parts of water to 1 part of coating solution.

Chemical Control Bonderite® 1402W coating Bonderite® 1402W coating Bonderite® 1402W coating Bonderite@ 1402W coating Part B 336 Hour Salt Spray Test Chemical Control Bonderite® 1402W coating Bonderite® 1402W coating Bonderite® 1402W coating 21 Part A 168 Hour Salt Spray Test Treatment No Treatment applied, air dried applied, blow dried and painted double application, blow dried applied, air dried, painted Treatment No Treatment applied, blow dried with hair dryer applied, air dried double application blow dried Result Corroded Pass Pass Pass Pass Result Corroded Pass Pass Pass Test #4 Test #4 used an Alodine® 1132 no-rinse chrome-containing coating containing a fluorinated surfactant sold by the Henkel Corporation of Gulph Mills, Pennsylvania.

Chemical Control Bonderite® 1132 coating Part A 168 Hour Salt Spray Test Treatment No Treatment applied, air dried Result Corroded Pass Bonderite® 1132 coating Bonderite® 1132 coating Bonderite® 1132 coating Bonderite® 1132 conversion coating Chemical Control applied, blow dried applied, blow dried and painted double application blow dried applied, air dried painted Part B 336 Hour Salt Spray Test Treatment No Treatment applied, blow dried with hair dryer applied, air dried double application blow dried Pass Pass Pass Pass Result Corroded Marginal Fail Pass Bonderite® 1132 coating Bonderite® 1132 coating Bonderite® 1132 coating General In another preferred method of applying flowable materials, a Fluorad® fluorochemical surfactant is added to an aqueous chemical conversion coating composition, such as those previously mentioned. Fluorochemical surfactants lower the surface tension characteristics of these types of aqueous conversion coatings. A particular advantage of fluorochemical surfactants is that they have excellent chemical and thermal stability even in the presence of strong oxidizing agents such as chromates, even at low pH levels, making them particularly useful when using aqueous chromate-containing compositions.

Examples of these surfactants are sold under the tradenames Fluorad FC- 93 and Fluorad FC-120, by the 3M Company. Additional examples of these surfactants are sold as Zonyl FSA and Zonyl FSC surfactants by the Dupont Co. It has been found that it is advantageous to add from about 0.0001% to about 3% of a fluorochemical surfactant (by volume) to any aqueous acidic composition to improve the dispensing and coating characteristics of the composition, while improving the shelf-life of the dispenser because of the stability of the fluorochemical surfactants. Additionally, it has been found that it is advantageous to add from about 0.01% to about or preferably from 0.01% to 0.05%, of a fluorochemical surfactant (by volume) to any aqueous acidic composition. Because the fluorochemical surfactant lowers surface tension, an applied film of a solution containing it penetrates into scratches more readily, and also flows to form a film of a more uniform thickness, the coating is self-levelling.

In summary, it can be said that the present invention provides industry with an improved method for applying flowable materials to surfaces; and more particularly, of applying rust-proofing and conversion coatings to metals.

It will be recognized that the applicator must be constructed of materials that do not react with the chemical solution that is to be applied.

In use, the uncovered dispensing tip of a filled applicator is placed in contact with the surface to be coated in the same manner that a marking pen is used to apply a mark or a highlight. The solution in the reservoir feeds to the tip, as needed, when the tip is placed in contact with or rubbed on the surface.

The applicator and method have been tested using a MIL-C-5541E conversion coat testing specification. It has been shown that the applicator and method apply a minimal amount of conversion coating solution to the surface of the treated parts. During the chemical reaction process, the no-rinse type conversion coating solution dries on the surface leaving substantially no wasted solution.

Thus, the present invention may assist in eliminating the problems associated with conventional touch-up repair of conversion coat treated aluminum surfaces, and provides for a simple means to touch up and repair scratched parts with chemical solutions. The present invention may also reduce the repair cycle time in touching up and repairing scratched parts with chemical solutions, such as conversion coat-treated aluminum.

The applicator reduces solution waste by up to 99%, and the only waste material thrown away is in an expired or empty applicator.

According to a preferred embodiment of the applicator, its distal end is welded shut. The tubular housing is inverted on the distal end and the proximal 24 end is open. Filling of the chamber in the housing takes place by pouring the conversion coating into the chamber in the housing. Then, the Flocon® valve assembly is pressed forward within the housing to make a leak proof seal.

Thus there has been described a composition and method that may be used in touching up conversion coated aluminum surfaces, for example. It is to be understood that the above-described embodiments are merely illustrative of some of the many specific embodiments which represent applications of the principles of the present invention. Clearly, numerous and other arrangements can be readily devised by those skilled in the art without departing from the scope of the invention.

"Comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Claims (10)

1. 2. The method of claim 1 wherein said no-rinse composition includes from 0.1% to 1.0% by weight of a mixture of chromium compounds, from 0.1% to by weight of said water-soluble solution including polyacrylic acid and/or esters thereof, and the remainder including water.
2. 3. The method of claim 1 wherein said layer of applied liquid is force-dried by an air stream.
3. 4. The method of claim 3 wherein said air stream is at a temperature of 150OF or higher. The method of claim 3 wherein the velocity of said air stream is less than 3000 fpm.
4. 6. The method of claim 1 wherein said no-rinse composition further includes a functionally effective amount of an acid-stable fluorinated surfactant.
5. 7. The method of claim 6 wherein said acid-stable fluorinated surfactant includes from 0.01% to 0.05% by volume of said no-rinse composition.
6. 8. The method of claim 1 wherein said no-rinse composition includes chromium chromate.
7. 9. The method of claim 1 wherein said no-rinse composition includes C chromium phosphate. U The method of claim 1 wherein said no-rinse composition includes an tC) accelerated chromium chromate composition.
8. 11. The method of claim 1 wherein said no-rinse composition includes zirconium phosphate. (Ni
9. 12. The method of claim 1 wherein said no-rinse composition includes zinc Sphosphate and said metal surface to be treated is selected from the group consisting of steel, galvanized steel, iron, aluminium and zinc.
10. 13. A no-rinse method for repairing a damaged coating on a metal surface substantially as hereinbefore described with reference to the drawings. DATED this 12th day of December 2005 HENKEL CORPORATION WATERMARK PATENT TRADE MARK ATTORNEYS GPO BOX 2512 PERTH WA 6001 AUSTRALIA P8055AU03