KR20130117853A - Methods of removing rust from a ferrous metal-containing surface - Google Patents

Abstract

The present application is directed to a method of removing rust from an iron metal containing surface. The method includes contacting a surface with a composition comprising carboxylic acid, synthetic hectorite clay, and water.

Description

METHODS OF REMOVING RUST FROM A FERROUS METAL-CONTAINING SURFACE}

The present invention particularly relates to a method for removing rust from an iron metal containing surface.

During processing or simply exposure to the atmosphere, the metal oxide layer, ie rust, often forms over all or part of the ferrous metal surface, thereby impairing its appearance and / or suitability for further use. One example is steel, such as mild steel, used in the manufacture of various products. Therefore, it is often desirable to remove the metal oxide layer. Typically, the removal is carried out by treating the rusty metal surface with strong acids such as nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid. However, these strong acidic, corrosive and caustic chemicals are often undesirable from an environmental and safety standpoint.

In some cases, the ferrous metal to be treated can be oriented in a substantially vertical manner, for example in the case of large structures such as storage tanks, ships and other means of transport and bridges. In addition, sprayable products are often desirable for ease of use and efficiency.

Accordingly, there is a need to provide a method for removing rust from ferrous metal containing surfaces, including those oriented in a substantially vertical manner, using sprayable compositions that do not contain environmentally undesirable strong acids.

In certain aspects, the present invention relates to a method for removing rust from an iron metal containing surface. Such methods include (a) carboxylic acids; (b) synthetic hectorite clay; And (c) contacting the surface with a composition comprising water. The invention also relates, in particular, to ferrous metal containing surfaces treated by the method described above.

For the purposes of the following detailed description, it will be understood that the invention may assume various alternative modifications and step sequences, except where noted to the contrary. Moreover, unless otherwise stated or otherwise stated, for example, all numbers expressing quantities of ingredients used in the specification and claims are to be understood as being modified by the term "about" in all examples. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At least, rather than attempting to limit the application of doctrines equivalent to the scope of the claims, each numerical parameter should be construed at least in terms of the number of reported significant digits and by applying conventional rounding techniques.

Notwithstanding that the numerical ranges and parameters setting the broad scope of the invention are approximations, the numerical values set in the specific examples are reported as precisely as possible. However, any numerical value essentially contains certain inevitable errors resulting from the standard deformations found in each test measurement.

In addition, it is to be understood that any numerical range recited herein includes all sub-ranges subsumed therein. For example, the range "1 to 10" is intended to include all subranges between (and including) the minimum value 1 mentioned and the maximum value 10 mentioned, that is, the minimum value of 1 or more and the maximum value of 10 or less. do. The use of the singular herein includes the plural unless the context clearly indicates otherwise, the plural encompasses the singular. In addition, although "and / or" may be explicitly used in certain examples, the use of "or" herein means "and / or" unless specifically stated otherwise.

As mentioned, certain embodiments of the invention relate to a method for removing rust from ferrous metal containing surfaces. As used herein, the term “rust” refers to a coating or thin film formed on a metal by oxidation or corrosion. In some cases, the rust removed by the method of the present invention is “red rust”, which refers to a coating or thin film formed on iron or steel by oxidation during exposure to air and / or moisture, as used herein, and iron oxide (II) (FeO, Bustite), alpha phase iron (III) oxide (α-Fe ₂ O ₃ , hematite), beta phase iron oxide (III) (β-Fe ₂ O ₃ ), gamma iron oxide (III) ( γ-Fe ₂ O ₃ , maghemite), epsilon iron oxide (III) (ε-Fe ₂ O ₃ ), iron hydroxide (II) (Fe (OH) ₂ ), iron hydroxide (III) (Fe (OH) ₃ , Vernite), and / or the hydrated form and any combination thereof. In some embodiments, the iron oxide removed by the method of the present invention is often in the form referred to as "mill scale", which, as used herein, iron or iron by oxidation during exposure to air, moisture and / or heat. Refers to a coating or thin film formed on steel, and includes iron oxide (II, III) (Fe ₃ O ₄ , magnetite), alpha phase iron oxide (III) (α-Fe ₂ O ₃ , hematite), iron hydroxide (II) (Fe ( OH) ₂ ), iron (III) hydroxide (Fe (OH) ₃ , vernalite), and / or the hydrated forms and combinations of any of the above.

Metal surfaces that can be treated by the process of the invention include steels coated with cold rolled steel, hot rolled steel, zinc metal, zinc compounds, or zinc alloys, such as electrogalvanized steel, hot dip galvanized steel, galvanized steel, and Includes, but is not limited to, surfaces consisting of steel plated with zinc alloys. Surfaces composed of mild steel can be treated with the method of the present invention. As used herein, mild steel refers to low carbon steel containing less than 0.25 weight percent carbon.

In the process of the invention, the metal surface is contacted with a composition comprising carboxylic acid. In certain embodiments, the carboxylic acid selected for use in the compositions described herein has a water solubility of greater than 1 g / L at 20 ° C. Suitable carboxylic acids for use in the compositions used in the process of the invention are, for example, monocarboxylic acids such as formic acid, acetic acid, propionic acid, methyl acetic acid, butyric acid, ethyl acetic acid, n- valeric acid, n-butanecarboxylic acid, acrylic acid, propiolic acid , Methacrylic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid; Dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, subberic acid, azelaic acid, repartic acid, sebacic acid, maleic acid and fumaric acid; Aliphatic hydroxy acids such as glycolic acid, lactic acid, tartronic acid, glyceric acid, malic acid, tartaric acid, citramal acid, citric acid, isocitric acid, leucine acid, mevalonic acid, pantoic acid, resinoleic acid, ricinellanic acid, cerebonic acid, Quinic acid and shikimic acid; Aromatic hydroxy acids such as salicylic acid, creosotic acid, vanylic acid, silingic acid, pyrocatechuic acid, resorcylic acid, protocatechuic acid, gentisic acid, orcelinic acid, gallic acid, mandelic acid, benzyl acid, atrolactic acid, mel Lilot acid, floretic acid, kumaric acid, umbelic acid, caffeic acid, ferulic acid and citric acid. In addition, mixtures of any of the above may be used.

In certain embodiments, the carboxylic acid is present in the composition used in the methods of the present invention in an amount of at least 1% by weight, such as at least 10% by weight, or in some cases at least 15% by weight, based on the total weight of the composition. In certain embodiments, the carboxylic acid is present in the composition used in the methods of the present invention in an amount of up to 50 wt%, such as up to 30 wt%, or in some cases up to 25 wt%, based on the total weight of the composition.

In the process of the invention, the composition in contact with the ferrous metal containing surface also comprises synthetic hectorite clay. The presence of synthetic hectorite clay in the presently described compositions results in thickened compositions with high shear reduction, thixotropic rheology. As a result, the composition is sprayable using conventional spraying devices (including those mentioned below), but remains on the ferrous metal-containing surface, even if the surface is oriented substantially vertically for a time sufficient to perform rust removal. It is found to be. The term "substantially vertical" as used herein means that the ferrous metal containing surface is substantially perpendicular to the ground or other surface (ie within ± 20% of vertical) when disposed. Indeed, the use of synthetic hectorite clays, in contrast to other thickeners including other thixotropic clays (eg kaolin and bentonite clay), is sprayable at ambient conditions and even when the surface is substantially vertically oriented There is a surprising finding that produces a composition that can be effective to remove rust from the lysate. It is presently believed that the amount of other thixotropic clay required to produce a composition effective to remove rust from a substantially vertically oriented surface results in a composition that is not sprayable at ambient conditions. As used herein, “ambient conditions” refer to 23 ° C. and atmospheric pressure.

Synthetic hectorite clays suitable for use in the compositions described herein include, for example, LAPONITE RD, LAPONITE RDS and LAPONITE JS, and combinations thereof. do. As will be appreciated, each of these is layered structured magnesium silicate according to the formula NaO ₃ (Mg, Li) ₃ Si ₄ O ₁₀ (F, OH) ₂ . Laponite Aldi is a free flowing silicate composite layer having a bulk density of 1,000 kg / m ³ , a surface area of 370 m ² / g (BET), a 2% suspension in water of pH 9.8, wherein the dry weight composition is 59.5% SiO ₂ , 27.5% MgO, 0.8% Li ₂ O and 2.8% Na ₂ O. In addition, Laponite Aldies is a free flowing silicate synthetic layer having a bulk density of 1,000 kg / m ³ , a surface area of 330 m ² / g (BET), a 2% suspension in water of pH 9.7, At this time, the dry weight composition is 54.5% SiO ₂ , 26.0% MgO, 0.8% Li ₂ O, 5.6% Na ₂ O and 4.1% P ₂ O ₅ . For example, the particle size of the synthetic hectorite described above is typically an average diameter of 1 to 30 nm.

In certain embodiments, synthetic hectorite clay is present in the composition used in the methods of the present invention in an amount of at least 1% by weight, such as at least 2% by weight, or in some cases at least 3% by weight, based on the total weight of the composition. In certain embodiments, the synthetic hectorite clay is present in the composition used in the methods of the present invention in an amount of up to 10 wt%, such as up to 6 wt%, or in some cases up to 5 wt%, based on the total weight of the composition. .

In certain embodiments, the composition used in the method of the present invention further comprises a source of chloride ions. The presence of a source of chloride ions can be particularly beneficial when the removal of dark skin is required or desired. For example, suitable chloride sources include, in particular, hydrochloric acid, calcium chloride, sodium chloride, ammonium chloride and potassium chloride.

In certain embodiments, the chloride source is present in the composition used in the methods of the present invention in an amount of at least 1% by weight, such as at least 2% by weight, or in some cases at least 3% by weight, based on the total weight of the composition. In certain embodiments, the chloride source is present in the composition used in the methods of the present invention in an amount of up to 10 weight percent, such as up to 8 weight percent, or in some cases up to 6 weight percent, based on the total weight of the composition.

In certain embodiments, the composition used in the method of the present invention further comprises an organic solvent, such as a water miscible organic solvent. Suitable such solvents include monoalkyl or dialkyl ethers of ethylene glycol or diethylene glycol, or monoalkyl, dialkyl or trialkyl ethers of triethylene glycol and acetate derivatives thereof. Alkyl groups are often in the range of 1 to 4 carbon atoms. Suitable examples are saturated glycols containing at least 4 carbon atoms or compounds containing formula (I):

(I)

Where

R is independently selected from hydrogen, alkyl of 1 to 4 carbon atoms and-(O) C-CH ₃ ;

R ₁ is independently selected from the group consisting of —CH ₂ , —CH ₂ —CH—, —CH ₂ —CH (CH ₃ ) — and —CH (CH ₂ OH) —;

R ₂ is independently selected from the group consisting of alkyl of 1 to 4 carbon atoms, hydroxyl substituted with alkyl of 1 to 4 carbon atoms, and — (O) C—CH ₃ .

Examples of solvents are Cellosolve (tradename for monoethyl ether of ethylene glycol), methyl cellosolve, butyl cellosolve, isobutyl cellosolve, hexyl cellosolve, Carbitol (monoethyl of diethylene glycol Brand name for ether), butyl carbitol, hexyl carbitol, monobutyl ether of propylene glycol, monopropyl ether of propylene glycol, monomethyl ether of propylene glycol, monomethyl ether of dipropylene glycol, butoxytriglycol C ₄ H ₉ O (C ₂ H ₄ -O) ₃ H, methoxytriglycol CH ₃ O (C ₂ H ₄ -O-) ₃ H, ethoxytriglycol C ₂ H ₅ O (C ₂ H ₄ O) ₃ H 1, butoxyethoxy-2-propanol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol (having a molecular weight of 2000 or less), hexylene glycol , 2 ethyl-1 , 3-hexane diol; 1,5-pentane diol, ester diol-204 (2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl-3-hydroxyl propionate), and the like.

Suitable water miscible alcohols that may be used in the present invention are those having 1 to 8 carbon atoms, such as methanol, ethanol, propanol, butanol, isobutanol, pentanol, hexanol, heptanol, octanol, methylamyl alcohol and the like. .

Suitable water miscible aliphatic ketones that can be used in the present invention are acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methoxy acetone, cyclohexanone, methyl n-amyl ketone, methyl isoamyl ketone , Ethyl butyl ketone, diisobutyl ketone, isophorone, acetyl acetone (2,4-pentane dione), diacetone alcohol ((CH ₃ ) ₂ C (OH) CH ₂ C (O) CH ₃ ).

In certain embodiments, the organic solvent is present in the composition used in the methods of the present invention in an amount of at least 1% by weight, such as at least 2% by weight, or in some cases at least 3% by weight, based on the total weight of the composition. In certain embodiments, the chloride source is present in the composition used in the methods of the present invention in an amount of up to 10 weight percent, such as up to 8 weight percent, or in some cases up to 6 weight percent, based on the total weight of the composition.

In addition, the compositions used in the methods of the present invention may include any of a variety of optional ingredients such as colorants, surfactants, corrosion inhibitors, preservatives, fillers, abrasives, buffers, flavors and the like.

The remainder of the composition used in the process of the invention is typically water, such as deionized water.

In certain embodiments, the compositions used in the methods of the present invention are substantially free of or completely free of strong acids that produce environmentally undesirable byproducts such as phosphoric acid and / or sulfuric acid. "Substantially free" as used herein in the absence of a strong acid in a composition described herein means that the composition comprises less than 1% by weight, such as less than 0.1% by weight. As used herein, “completely free” means no strong acid in the composition.

In certain embodiments, the compositions used in the methods of the present invention have a low shear viscosity of at least 1,000 Pa.s, such as at least 2,000 Pa.s, or in some cases at least 4,000 Pa.s or at least 5,000 Pa.s. "Low shear viscosity" means a shear rate of 0.01 s ^(-1) and Refers to the viscosity measured on a Physica MCR 301 viscometer using the CP50-1 / TG axis for 70 seconds at 23 ° C. In certain embodiments, the composition used in the process of the present invention has a high shear viscosity of 0.50 Pa · s or less, such as 0.1 Pa · s or less, or in some cases 0.01 Pa · s or less (“high shear viscosity” as used herein). Has a shear rate of 10 ⁽⁴⁾ s ^(-1) and viscosity measured on a Piscia MCR 301 viscometer using the CP50-1 / TG axis for 5 seconds at 23 ° C.).

In certain embodiments, the pH of the composition used in the process of the invention is 6.0 or less, such as 2.0 to 5.0, or in some cases 3.0 to 4.0.

In the process of the invention, the composition is contacted with the metal containing surface by any of a variety of methods, in particular by brushing, spraying or dipping. The compositions described herein are particularly suitable for spray applications using conventional pressure port equipment or HVLP equipment. Because of the thixotropic properties of the compositions described herein, the process of the invention may be suitable for use with substantially vertically oriented ferrous metal containing surfaces, for example, for large structures such as in particular storage tanks, bridges, ships And other transportation means.

Once applied, the composition is left on a metal containing surface to remove rust to the desired or required degree. Contact times often range from at least 5 minutes to several hours, often at least 30 minutes, in some cases at least 3 or 4 hours, depending on the severity of the rust and the temperature at which the cleaning is performed. The surface from which the rust has been removed may then be washed with water to remove the compositions described herein, ie loose rust and dissolved rust. In some cases, application of more than one of the compositions described herein may be desirable. It may also be desirable to apply the compositions described herein after mechanically removing loose rust and scale by wire brushing.

The invention also relates in particular to metal surfaces treated by the process of the invention.

The invention is illustrated by the following examples which are not to be considered as limiting the invention in its details. Throughout the application as well as the examples, all parts and percentages are by weight unless otherwise indicated.

Example  One

Five solutions were prepared using the ingredients and amounts in g listed in Table 1 below. 3x4 inch bare cold rolled steel panel (ACT Test Panel LLC 273 Industry, 49242 Drive Hillsdale, Mich.) With commercial alkaline cleaners (CK2010, commercially available from Fiji Industries, Inc.). Available from US), and the panel was left in a salt spray room for 4 hours. The panels were rinsed with deionized water and air dried at room temperature before being applied to the solution.

ingredient Example 1A Example 1B Example 1C Example 1D Example 1E Laponite Aldi ¹ 6 - - - - Klucel M ² - 1.5 - - - Klucel H ³ - - 1.5 - - Polyvinylpyrrolidone ⁴ - - - 15 - Gelatin (calfskin) ⁵ - - - - 15 Deionized water 114 118.5 118.5 105 105 Citric acid 30 30 30 30 30 ¹ Laponite Aldi is commercially available from Southern Clay Products, Inc. In Example 1A, laponite aldi was incorporated into water according to the manufacturer's instructions. Then, citric acid was added slowly while stirring the solution.
² Klucel M is hydroxyl propyl cellulose (M _w of about 850,000) commercially available from Hercules Inc. In Example 1B, Klucel M material was transferred to water with stirring. After dissolving the material, citric acid was added slowly while stirring.
³ Klucel H is commercially available hydroxyl propyl cellulose (M _w of about 1,150,000) from Hercules Incorporated. In Example 1C, Klucel H. material was transferred to water with stirring. After dissolving the material, citric acid was added slowly while stirring.
⁴ Polyvinylpyrrolidone is commercially available from Sigma-Aldrich Co. and has an average M _w of about 1,300,000. In Example 1D, polyvinylpyrrolidone was transferred to water with stirring. After dissolving the material, citric acid was added slowly while stirring.
⁵ Gelatin is commercially available from Sigma-Aldrich Company. In Example 1E, gelatin was transferred to water with stirring. After dissolving the material, citric acid was added slowly while stirring.

Test board

A portion of each of these solutions was applied via a pipette to a set of rusty steel panels placed at an angle of about 80 ° from horizontal. After 2 hours, the panels were rinsed with deionized water and examined for approximately% of rust removed. The investigation results are shown in Table 2 below.

Example Approximate% of Removed Rust 1A 100 1B 80 1C 90 1D 50 1E 30

Example  2

Three solutions were prepared using the ingredients and amounts in g listed in Table 3. In each example, the clay was transferred to water with stirring. Laponite aldi containing material showed an increase in viscosity a few minutes after incorporation. Within 20 minutes, the solution became clear with no visible particles. Bentonite solution showed very slight change in viscosity after addition to water and the material remained opaque bluish green. There was no change in viscosity after adding the kaolin material. After each clay was added, the solution was stirred for about 20 minutes, citric acid was added and the resulting mixture was stirred for about 10 minutes.

ingredient Example 2A Example 2B Example 2C Deionized water 380 380 380 Laponite Aldi ¹ 20 - - Bentonite ² - 20 - Kaolin ² - - 20 Citric acid 100 100 100 ¹ Commercially available from Southern Clay Products Incorporated.
² Commercially available from VWR International, LLC.

Rusty panels were prepared as described in Example 1. Three solutions were sprayed using a garden sprayer to a panel placed at an angle of about 80 ° from horizontal. After 1 hour, the panels were rinsed with water and the amount of rust removed was visually assessed. About 100% of rust was removed with the solution of Example 2A, while none of Examples 2B and 2C showed any rust removal.

The rheology of the three solutions was measured using a Parar-Physica MCR 301 rheometer with various shear rates and CP50-1 / TG axis at 23 ° C. The measurement results are shown in Table 4 below.

Shear rate (1 / s) Example 2A (Pas) Example 2B (Pas) Example 2C (Pas) 0.01 5,040 35.8 8.92 0.1 457 4.65 1.03 One 54.2 0.551 0.115 10 4.42 0.0678 0.0295 100 0.319 0.0141 0.00693 1000 0.0683 0.00641 0.00328

Example  3

Three solutions containing the same theoretical amount of chloride were prepared using the ingredients and amounts in g listed in Table 5 below. In each case laponite aldi was incorporated into the water according to the manufacturer's instructions. Then, citric acid was added slowly while stirring the solution. Then hydrochloric acid was added dropwise while stirring for Example 3A. Sodium chloride was then added with stirring for Example 3B. Ammonium chloride was then added with stirring for Example 3C.

ingredient Example 3A Example 3B Example 3C Deionized water 317.5 342.9 346.1 Laponite Aldi 20 20 20 Citric acid 100 100 100 37% HCl ¹ 62.5 - - NaCl ¹ - 37.1 - NH ₄ Cl ¹ - - 33.9 ¹ Commercially available from VDL International LLC.

Rusty panels were prepared as described in Example 1. Three solutions were applied to panels placed at an angle of about 80 ° from horizontal. After 1 hour, the panels were rinsed with water and the amount of rust removed was visually assessed. Using all three solutions eliminated about 100% of rust.

Example  4

Three solutions containing the same theoretical amount of carboxylic acid containing compound were prepared using the ingredients and amounts in g listed in Table 6 below. In each case laponite aldi was incorporated into the water according to the manufacturer's instructions. The acid was then added slowly while stirring the solution.

ingredient Example 4A Example 4B Example 4C Deionized water 106.5 106.5 116 Laponite Aldi 6 6 6 Lactic Acid (80% in H ₂ O) ¹ 37.5 - - Tartaric Acid (80% in H ₂ O) ¹ - 37.5 - Citric acid - - 30 ¹ Commercially available from VDL International LLC.

Rusty panels were prepared as described in Example 1. Three solutions were applied to panels placed at an angle of about 80 ° from horizontal. After 1 hour, the panels were rinsed with water and the amount of rust removed was visually assessed. Using all three solutions eliminated about 100% of rust.

It will be appreciated by those skilled in the art that changes may be made to the embodiments described above without departing from the broad inventive concept. Accordingly, it is to be understood that the invention is not intended to be limited to the particular embodiments disclosed, but is intended to cover modifications that fall within the spirit and scope of the invention as defined in the appended claims.

Claims (20)

(a) carboxylic acid;
(b) synthetic hectorite clay; And
(c) Water
A method of removing rust from an iron metal containing surface comprising the step of contacting the surface with a composition comprising a. An iron metal containing surface treated by the method of claim 1. The method of claim 1,
And wherein the rust comprises iron oxide and / or iron hydroxide. The method of claim 1,
How ferrous metals contain steel. The method of claim 1,
How steel includes mild steel. The method of claim 1,
And the carboxylic acid comprises an aliphatic hydroxy acid. The method according to claim 6,
Wherein the aliphatic hydroxy acid comprises citric acid. The method of claim 1,
Wherein the carboxylic acid is present in the composition in an amount of at least 10% and at most 30% by weight based on the total weight of the composition. The method of claim 1,
Synthetic hectorite clay has the formula NaO ₃ (Mg, Li) ₃ Si ₄ O ₁₀ (F, OH) ₂ . The method of claim 1,
The average diameter of the synthetic hectorite is 1 to 30 nm. The method of claim 1,
Wherein the synthetic hectorite clay is present in the composition in an amount of at least 1 wt% and up to 10 wt% based on the total weight of the composition. The method of claim 1,
Wherein the composition further comprises a source of chloride ions. The method of claim 1,
Wherein the composition has a low shear viscosity of at least 1,000 Pa · s and a high shear viscosity of at most 0.50 Pa · s. The method of claim 13,
Wherein the composition has a low shear viscosity of at least 4,000 Pa · s and a high shear viscosity of at most 0.01 Pa · s. The method of claim 1,
The pH of the composition is 6.0 or less. The method of claim 1,
Contacting comprises spraying the composition onto the metal containing surface. The method of claim 17,
Wherein the ferrous metal containing surface is oriented substantially vertically. (a) carboxylic acid;
(b) synthetic hectorite clay; And
(c) Water
Spray applying the composition comprising at least a portion of the ferrous metal containing surface;
(i) the ferrous metal containing surface is oriented substantially vertically,
(ii) the composition has a low shear viscosity of at least 1,000 Pa · s and a high shear viscosity of at most 0.50 Pa · s,
Method for removing rust from ferrous metal containing surface. The method of claim 18,
Wherein the composition further comprises a source of chloride ions. The method of claim 18,
The carboxylic acid comprises citric acid.