AU2006203105A1 - Surface Treatment Composition and Method of Use - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventors Address for service is: ATBM Pty Ltd Dean WALKLEY Curt Holger HENKEL WRAY ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR Invention Title: Surface Treatment Composition and Method of Use The following statement is a full description of this invention, including the best method of performing it known to me:- -2c Surface Treatment Composition and Method of Use Field of the Invention The present invention relates to a surface treatment composition and methods of use thereof. The composition of the present invention has particular application in the cleaning of metallic surfaces and the removal and or inhibition of rust.

SBackground Art When metals are exposed to oxygen in the atmosphere they form an oxide. With steel, the metal forms Ferric oxide (Fe 2 0 3 or red rust, which flakes off and exposures the underlying layer to further oxygen attack. Once rust is formed, further oxygen is allowed to react with the underlying metal. In the case of aluminium, the aluminium oxide actually forms an oxygen impervious layer and prevents further oxidation. Fresh aluminium will react with oxygen very quickly.

Other metals, such as stainless steel, copper, brass and platinum form an oxide layer on the surface, creating a dull surface.

Rust treatment and or prevention There are many known methods in which to prevent and or treat rust. However, most of these methods are either time consuming and expensive or involve the use of dangerous chemicals. In addition, rusting may still occur under the coating, and result in "bubbling" of the surface.

One known method of preventing corrosion of steel is use of sacrificial zinc anodes- This process involves forming an electrochemical cell under conditions in which the two metals (zinc and steel) are in contact. By this method, anodic dissolution of iron caused by local cell formation when iron alone is exposed to a corrosive environment is suppressed, thus preventing corrosion of the steel.

Accordingly, anti-rust effectiveness of the iron and zinc combination ends at the point in time when the zinc in contact with the steel is consumed, so that corrosion of the zinc layer must be suppressed in order to obtain an enduring protective -3effect from the zinciferous coating. To prevent the corrosion of the zinc layer, the steel is subjected to a chromate treatment. Although it is a highly effective and economical method, the steel eventually corrodes.

Phosphoric acid has been used by direct application to rusted iron or steel surfaces to convert iron (111) oxide to a water soluble phosphate. Phosphoric acid is capable of dissolving iron oxide quickly, whilst etching iron very slowly.

Therefore, exposure of steel to phosphoric acid should be for the minimum etch Itime that removes all rust. After treatment, the reddish brown iron oxide is 0converted into a black iron phosphate compound that may be removed from the surface. However, the blackening of the iron is often not a desirable result and may create a rough, less durable surface. In addition, phosphoric acid may-be is a skin irritant.

Other acids may also be used in the treatment of rust. However, these acids are not as selective. Hydrochloric acid and sulphuric acid etch rust very quickly. In addition, oxalic acid has also been used. However, if metal in left exposed to these acids too long, a significant amount of metal may be lost. In addition, none of these acids leaves a protective film behind. Finally, all of these acids are dangerous for use.

Other rust treatment products contain polymers that treat the surface of the corroded metal, leaving only lower corroded strata untreated, which may lead to further corrosion after application of surface coatings such as paint.

SCleaners Exposure of a metal surface to oxygen in the atmosphere results in the often undesired dulling of the surface. For example, aluminum surfaces, such as boats, pans, utensils and other surfaces, loose their shine. In addition, stainless steel, platinum, brass, bronze and copper also becomes dull over time and exposure to the atmosphere.

IND

Known metal surface treatments to improve shine include the use of include wax based polish, abrasive wax, abrasive cleaners, non-etching chemical cleaners, and solvents such as kerosene, turpentine and white spirits. However, many cleaners contain hydrofluoric acid, an extremely corrosive and dangerous compound. Even extremely small amounts, left untreated on skin, can result in excruciating pain and can be life-threatening. Further, use of any of the above mentioned cleaners requires the metal surface to be continually cleaned, as a result of the further oxidation of the surface layer.

The preceding discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia, or anywhere else, as at the priority date of the application.

Summary of the Invention The present invention arises from the unexpected finding that an aqueous composition comprising phosphorous acid and zinc ions is capable of removing rust from a surface and inhibiting rust formation. In addition, the composition of the present invention is capable of cleaning surfaces, including metal surfaces and concrete.

According to a first aspect of the invention, there is provided a surface treatment composition comprising an aqueous solution of phosphorous acid and zinc ions QAccording to a second aspect of the invention, there is provided a composition for

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rremoving rust from a surface, the composition comprising phosphorous acid and zinc ions in solution.

According to a third aspect of the present invention, there is provided a composition for inhibiting rust formation on a surface, the composition comprising phosphorous acid and zinc ions in solution.

IAccording to a fourth aspect of the present invention, there is provided a 0composition for cleaning a surface, the composition comprising at least phosphoric acid and zinc ions in solution.

According to a fifth aspect of the present invention, there is provided a method for the preparation of a surface treatment composition, the method including the steps of: adding phosphorous acid to water to provide a first solution; adding a source of zinc ions to water to provide a second solution; and adding the second solution to the first solution.

According to a sixth aspect of the present invention, there is provided a method for removing rust from a surface, wherein the method comprises the steps of: (a) applying at least one coating of the composition of the present invention to the surface, allowing the composition to react for a suitable period of time.

The above method may also be employed to inhibiting the formation of rust on steel. In addition, the method may also be used to clean metal surfaces and other surfaces.

-6- (N Disclosure of the Invention General (Ni Those skilled in the art will appreciate that the invention described herein is _susceptible to variations and modifications other than those specifically described.

It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features.

Any manufacturer's instructions, descriptions, product specifications, and product sheets for any products mentioned herein or in any document incorporated by reference herein, are hereby incorporated herein by reference, and may be employed in the practice of the invention.

The present invention is not to be limited in scope by any of the specific embodiments described herein. These embodiments are intended for the purpose of exemplification only. Functionally equivalent products, formulations and methods are clearly within the scope of the invention as described herein.

The invention described herein may include one or more range of values (eg size, concentration etc). A range of values will be understood to include all values within the range, including the values defining the range, and values adjacent to the range which lead to the same or substantially the same outcome as the values immediately adjacent to that value which defines the boundary to the range.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

-7- (NI Detailed Description of the Invention

Z

In accordance with the present invention, there is provided a surface treatment composition comprising an aqueous solution of phosphorous acid and zinc ions.

As used herein, the term phosphorous acid shall be taken to include, without limitation, acid of the formula HPO(OH) 2 and the structure shown below:

OO

I

H-P-OH

OH

Phosphorous acid may also be referred to as orthophosphorous acid, dihydroxyphosphine oxide or phosphonic acid.

The composition of the present invention has application in the cleaning of surfaces including metal surfaces, such as iron, galvanised steel and stainless steel, aluminium, alloys, welding seams, copper, platinum, brass; and other types of surfaces, such as concrete.

Advantageously, the composition of the present invention does not comprise hydrofluoric acid, thereby providing significant safety advantages over aluminium cleaners of the prior art.

Inhibition and treatment of rust The composition of the present invention has application in the treatment of rust on metallic surfaces and in particular, on ferrous surfaces. The rust may be provided in the form of an oxide, a calcite, a carbonate or a silicate. Without being limited by theory, it is believed that where the composition is used in the treatment of rust on ferrous surfaces, the composition forms a protective layer on the ferrous surface. Without being limited by theory, it is believed that the protective layer is an iron/zinc phosphite complex. Preferably, the protective layer is substantially -8water resistant. Without being limited by theory, it is believed that the protective layer is substantially impervious to oxygen.

Without being limited by theory, it is believed that the iron/zinc phosphite complex is a crystalline complex consisting of alternating layers of HPO 3 tetrahedrons and metal cations.

When used as a treatment for rust, the composition of the present invention has Ithe advantage of not forming a blackened surface. Although initially provides a good protection for steel, it creates a blackened rough surface that may not be as durable as the original steel surface. In addition, the black rust may not necessarily provide a long term solution to the reformation of rust by exposure to the atmosphere.

Therefore, in accordance with a further aspect of the present invention, there is provided a composition for removing rust from a surface, the composition comprising an aqueous solution of phosphorous acid and zinc ions.

In accordance with a further aspect of the present invention, there is provided a composition for inhibiting the formation of rust on a surface, the composition comprising an aqueous solution of phosphorous acid and zinc ions.

The amount of phosphorus acid required in the composition of the present invention is preferably, between about 1 to 90 by weight phosphorous acid.

More preferably the composition comprises between about 10 to 80 by weight phosphorous acid. In another preferred embodiment of the invention, the composition comprises between about 20 to 70 by weight phosphorous acid.

In a highly preferred embodiment of the present invention, the composition comprises about 60 by weight phosphorous acid.

The amount of zinc required in the composition of the present invention is preferably between about 0.05% to 10 by weight zinc. More preferably, the composition comprises between about 1 to 8 by weight zinc. In another preferred embodiment, the composition of the present invention comprises -9- Qbetween about 1 to 5 by weight zinc. In a highly preferred embodiment of

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Sthe present invention, the composition comprises about 2 by weight zinc.

c-i Cleaner The composition of the present invention may also be used to clean surfaces. For example, the composition may be used to clean metal surfaces. The following is a non-limiting list of metals that the composition of the present invention may be Iused to clean: aluminium, stainless steel, brass, platinum, and copper. In addition, the composition of the present invention may be used to clean surfaces such as concrete.

Without being limited by theory, it is believed that the zinc in the cleaner may provide some benefit to the surface by increasing the ability of the surface to shine by the deposition of a thin layer of zinc.

Therefore, in accordance with a further aspect of the present invention, there is provided a composition for cleaning a surface, the composition comprising an aqueous solution of phosphorous acid and zinc ions.

The amount of phosphorus acid required in the composition of the present invention to clean a metal surface is preferably between about 1 to 90 by weight phosphorous acid. More preferably the composition comprises between about 10 to 80 by weight phosphorous acid. In another preferred embodiment of the invention, the composition comprises between about 20 to by weight phosphorous acid. In a highly preferred embodiment of the present invention, the composition comprises about 60 by weight phosphorous acid.

The amount of zinc required in the composition of the present invention to clean a surface, such as aluminium or stainless steel, is preferably between about 0.05% to 10 by weight zinc. More preferably, the composition comprises between about 1 to 8 by weight zinc. In another preferred embodiment, the composition of the present invention comprises between about 1 to 5 by Qweight zinc. In a highly preferred embodiment of the present invention, the

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rcomposition comprises about 2 by weight zinc.

N To clean a surface such as concrete, the composition of the present invention requires dilution. Preferably the composition is diluted 50 parts composition to one part water.

In accordance with the present invention, there is also provided a method for the Ipreparation of a surface treatment composition, the method including the steps of: adding phosphorous acid to water to provide a first solution; adding a source of zinc ions to water to provide a second solution; and adding the second solution to the first solution.

The source of zinc ions may be provided in the form of zinc or a zinc salt including zinc oxide. It was found that other forms of zinc, such as zinc sulphates, zinc acetates and zinc chlorides did not give the required results.

In accordance with a further aspect of the present invention, there is provided a method for treating a surface with the composition of the present invention. That is, there is provided a method for removing rust from a surface, wherein the method comprises the steps of: applying at least one coating of the composition of the present invention to the surface, allowing the composition to react with the surface for a suitable period of time; and removing the composition from the surface.

The composition of the present invention also inhibits rust from reforming on the treated surface. Therefore, the present invention also provides a method for inhibits rust on a surface, wherein the method comprises the steps of: applying at least one coating of the composition of the present invention to the surface, (b) allowing the composition to for a suitable period of time.

11 The surface to be treated by either of the above methods may be steel. When the composition is used in a method to remove rust from steel or prevent rust formation on steel, it may be left in contact with the surface for a period of ranging between about 1 minute to about five hours.

It should be noted that the length of time required for the composition of the present invention to remove the rust from the surface depends on a variety of factors, including the amount of rust required to be removed, and the size of the Sarea to be treated. Therefore, a person skilled in the art would be aware of the N time required to remove and or prevent the formation of rust. Preferably, the composition of the present invention may be left in contact with the surface for between about 2 minutes to about 60 minutes.

Once the surface has been exposed to the composition of the present invention, the surface is rinsed to remove excess composition and the converted rust, as well as other un-reacted compounds. Water may be used to rinse the surface.

Excessive cleaning of the treated surface is not required.

If required, the surface may be treated with further applications of the composition of the present invention. That is, further coatings of the composition may be required to remove all the rust or to provide maximum protection from rust.

After rinsing the surface, the surface is allowed to dry. If a protective coating, such as paint, is to be applied to the surface after treatment, the surface should be allowed to dry for a period of between about 10 minutes to about 24 hours.

Preferably, the surface is allowed to dry over night before applying a surface coating.

The composition of the present invention may also be used in the inhibition of rust formation on steel. That is, the method outlined above may be used to treat steel prior to applying a protective coating, such as paint, or use of the steel product.

The time required for prevention of rust formation on steel may range from between one minute to about 5 hours. Preferably, the time of treatment is between about 5 minutes to about 30 minutes.

-12- QThe composition of the present invention may also be used to inhibit rusting of

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rwelding seams and to clean the slag from the seam. A welding seam is an alloy of compounds, as recommended for use for the material to be welded. A slag

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N consisting of the flux used in the welding process is formed over the weld. This material, when hot, is very pervious to the composition of the present invention.

STherefore, seams and the adjacent area normally affected by corrosion may be nprotected by the composition of the present invention. In addition, the slag is Neasily removed by the composition.

N The composition of the present invention may also be used in a method of cleaning surfaces, such as metals, including aluminium, stainless steel, platinum, copper, brass; and other surfaces such as concrete.

Therefore, according to a preferred embodiment of the present invention, there is provided a method for cleaning a surface, wherein the method comprises the steps of: applying at least one coating of the composition of the present invention to the surface, allowing the composition to react with the surface for a suitable period of time; and removing the composition from the surface.

For surfaces such as aluminium and stainless steel, the suitable time for cleaning the surface is between about 30 seconds to one hour. In a preferred embodiment of the invention, the composition is applied to the surface for between about 1 minute to about 5 minutes. Preferably, the composition is applied to the surface for about 2 minutes. However, the amount of cleaning required will influence the time required for the composition to clean the surface. In addition, the surface may require more than one treatment wit the composition. Further treatments may be applied either before or after rinsing the surface.

When the composition of the present invention is used to clean weld seams, the slag is permeable to the composition, and as such, the composition can pass through the slag and into the metal, where it is allowed to act as described above.

-13- N Best Mode(s) for Carrying Out the Invention The -composition of the present invention will now be described, by way of c example only, with reference to one embodiment of the composition method of application of the composition.

Composition Preparation

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ITo prepare the composition, phosphorous acid (600 g) was added to a first Ssample of water (400 mL) and the solution stirred until the phosphorous acid had dissolved. Zinc powder (20 g) was added to a second sample of water (200 mL) and the dispersion stirred. The zinc dispersion was added to the phosphorous acid solution and the mixture stirred until clear and made up to 1000 mL with the addition of further water.

Composition Application Before applying the composition to a surface, the surface should be cleaned of grease, oil, loose dirt and scale with degreaser, pressure cleaner or other effective means. The surface should be allowed to dry and a thin coat of the composition applied to the surface using a brush or spray and left on the surface for approximately one hour. For ferrous surfaces, it may be necessary to leave the composition on the surface for up to twenty four hours. After the required application period, the surface is thoroughly rinsed with water.

It will be appreciated that depending on the properties of the surface to be treated and the need for the treatment cleaning or rust treatment), the composition will be applied in different manners.

For lightly rusted ferrous surfaces, the composition was applied as a concentrate with a spray bottle or paintbrush. Within a few minutes, the corrosion was lifted from the surface and a coating of iron zinc phosphite complex was deposited.

The surface was rinsed with water and allowed to dry over night. A prime coat was then applied to some of the treated steel surfaces.

-14- For heavily rusted surfaces without scale, the composition was applied as a concentrate with a spray bottle or paintbrush. Within minutes the corrosion had begun to lift from the surface. After 24 hours, a second coat was applied and left 1 until a white powder appeared. It is believed this powder is a mixture of excess zinc and oxides of the components of treated steel. If required, a third coat was Sapplied onto the surface. The surface was then rinsed with water and allow to dry oover night.

(NO

For heavily rusted surfaces with scale, the scale was removed. A high pressure c water blaster, grinder, abrasive wheel or other effective mean may be used. The composition was then applied as a concentrate with a spray bottle or paintbrush.

Within minutes the corrosion began to lift from the surface. After anything from minutes to 24 hours the treated surface was rinsed with water and allowed to dry.

Some samples tested required a second coat and in some cases a third coat was applied to those surfaces that required further treatment. The treated surfaces were rinsed with water and allowed to dry.

To loosen rusted nuts and bolts, equal parts of the composition and water were mixed and the nuts and bolts immersed into the composition and soaked for an appropriate period of time. Depending on the type and condition of the steel, reaction time varied from 15 minutes high-tensile steel) to approximately 4 hours or more heavily corroded, low-grade steel).

The nuts and bolts were removed from the composition and the parts washed in water, then sprayed with the concentrate until a point where the composition formed drops, that is a slight excess of the composition was applied. This is believed to provide a rich zinc coating. The surface was allowed to dry, and then rinsed with water.

The composition was also used to test for assisting in the removal of rusted nuts and bolts and the like. The exposed nut and thread were sprayed and left for about 15 minutes. Depending on the severity of the corrosion a second application was required. Light wire brushing of the exposed thread and nut aided in removal of the rust.

To clean small items and automotive parts such as dye cast alloys, the item was immersed in the composition for about 15 to 30 minutes (or longer if heavily corroded) and rinsed thoroughly.

To clean welding seams, the composition was applied with a brush to the warm/hot arc welding seam and the slag removed in the usual fashion.

The composition used to clean the bottom surface of an aluminium dingy Icomprised 60 phosphorus acid 2 zinc ions in an aqueous solution. The composition was sprayed thinly onto half of the surface of the boat, ensuring the entire half of the surface was covered, and left overnight. In the morning, the composition was rinsed off and the resulting treated surface was significantly less dull than the untreated side.

The same solution was applied to a section of an aluminium surface of a tray of a utility vehicle. The solution was sprayed thinly onto the aluminium surface and left for about 20 minutes. After this time, the surface was rinsed briefly with water.

The surface was notably shinier than the untreated surface of the tray. A further treatment of the surface resulted in further cleaning of the tray.

Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Claims (14)

1. A surface treatment composition comprising an aqueous solution of phosphorous acid and zinc ions. S2. A composition according to claim 1 for removing rust from a surface. C 5 3. A composition according to claim 2 where in the surface is iron, steel, INO Sstainless steel or galvanised steel.

4. A composition according to claim 1 for inhibiting rust formation on a surface. A composition according to any one of claims 1 to 4 wherein the phosphorus acid required in the composition is between about 1% to about by weight phosphorus acid.

6. A composition according to claim 5 wherein the phosphorus acid required in the composition is between about 60% by weight phosphorus acid.

7. A composition according to any one of claim 1 to 6 wherein the zinc required in the composition is between about 10% to about 60% by weight zinc.

8. A composition according to claim 7 wherein the zinc required in the composition is about 40% by weight zinc.

9. A composition according to claim 1 for cleaning a surface.

10.A composition according to claim 9 wherein the surface to be cleaned is selected from the group comprising: aluminium, stainless steel, copper, brass, platinum, welding seams and concrete. ID-17- S11 .A composition according to claim 9 wherein the phosphorus acid required is between about 1% to about 90% by weight phosphorus acid. Z C 12.A composition according to claim 11 wherein the phosphorus acid required is about 60% by weight phosphorus acid.

13.A method for the preparation of the composition according to claim 1 Swherein the method comprises the steps of: IND Sadding phosphorus acid to water to provide a first solution; adding a source of zinc ions to water to provide a second solution; and adding the second solution to the first solution

14.A method for removing rust from a surface wherein the method comprises the steps of: applying at least one coating of the composition according to claim 1 to the surface; allowing the composition to react for a suitable period of time.

15.A method according to claim 14 further comprising the step of rinsing the treated surface.

16.A method for preventing rust formation on a surface wherein the method comprises the steps of: applying at least one coating of the composition according to claim 1 to the surface; allowing the composition to react for a suitable period of time. O -18- O 17.A method according to claim 16 further comprising the step of rinsing the treated surface. c18.A method for cleaning a surface wherein the method comprises the steps of: applying at least one coating of the composition according to claim 1 to the surface; (O S(b) allowing the composition to react for a suitable period of time.

19.A method according to claim 18 further comprising the step of rinsing the treated surface.

20.A composition according to claim 1 substantially as herein before described with reference to the examples.

21.A method according to any one of claims 13, 14, 16 and 18 substantially as herein before described with reference to the examples. Dated this TWENTIETH day of JULY 2006. ATBM Pty Ltd Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant