WO2018185429A1

WO2018185429A1 - Rust conversion agent

Info

Publication number: WO2018185429A1
Application number: PCT/FR2018/050833
Authority: WO
Inventors: Sabine Rouvreau; Christine Gaillon
Original assignee: Ascotec
Priority date: 2017-04-04
Filing date: 2018-04-04
Publication date: 2018-10-11
Also published as: CN110546213A; EP3607010A1; FR3064631B1; FR3064631A1

Abstract

The invention concerns a rust conversion agent consisting of one or more hydroxylated organic acid salts or a hydroxylated organic acid derivative, at least one of a passivating compound and a sequestering compound, and a solvent, the hydroxylated organic acid or acids or said derivative or derivatives being chosen from the hydroxylated carboxylic acids and the derivatives of same, different from tannic acid, and the carboxylic functions of which are chosen from the free carboxylic functions, the ester functions, the lactone functions and the anhydride functions.

Description

RUST CONVERTER AGENT

The invention relates to a rust treatment agent, and more specifically to a rust converting agent, as well as to its applications. In particular, it relates to this rust converter agent as a rust converter additive.

A rust converting agent is a compound or a mixture of compounds capable of transforming iron oxides and in particular iron hydroxide constituting essential rust, friable and resulting from the corrosion of iron or an alloy based on iron, in a more resistant compound, especially oxidation, and forming a protective barrier vis-à-vis a source of aggression. The traditional active ingredients are tannic acid, pyrogallol, oxalic acid, phosphoric acid and their derivatives, and are used alone or in mixtures. Among these, the most commonly used compounds are tannic acid and phosphoric acid which, in contact with rust, react with the iron oxides to form iron tannate and iron phosphate FePO ₄ , respectively .

Because of their acidic nature, in particular, these compounds have many disadvantages:

They can be added only in acidic coating formulations, using compatible resins such as chlorinated acid resins, cationic resins, etc.; the implementation of these resins is delicate, and furthermore, the field of application is restricted;

Once applied to the rust, a drying time of the rust converting agent layer of the order of 1 to 3 days must be respected, in particular before the application of an aqueous phase paint;

Treatment with such agents does not confer any protection of the metal support with respect to subsequent oxidation; for example, phosphoric acid forms a layer of iron phosphate on the treated metal, but it is too thin and too weak to be truly protective;

These ingredients have a dark color and it is therefore not possible to add them directly in aqueous phase paints without causing undesirable effects, such as the destabilization of the paint formulation, its browning ...

The invention provides a rust converter agent for overcoming all of the above disadvantages.

The rust converting agent according to the invention consists of one or more hydroxylated organic acid salts and / or one or more salts of an organic acid derivative. hydroxylated, at least one of a passivating compound and a sequestering compound, and a solvent, the hydroxylated organic acid or acids or the derivative (s) being chosen from hydroxylated carboxylic acids and their derivatives, different from the tannic acid, and whose carboxylic functions are chosen from free carboxylic functions, ester functions, lactone functions and anhydride functions. Advantageously, the agent of the invention comprises at least one passivating compound, and optionally a sequestering compound.

This agent is only slightly acidic and is not colored. As a result, such an agent is suitable for any support; as an additive, it can also incorporate any type of treatment product and / or coating a support, to overcome a prior stage of rust treatment, rust processing and treatment and / or the coating of the support being simultaneous. In addition, it has been observed that the addition of an agent of the invention to any treatment product and / or coating does not affect the properties of said agent and precisely its ability to transform rust.

Before describing the invention in more detail, terms used in the text are hereinafter defined.

By hydroxy carboxylic acid is meant any organic compound comprising at least one free carboxylic function -CQGH and at least one hydroxyl function -OH, primary, secondary or tertiary. By salt of a hydroxyl carboxylic acid is meant the compound resulting from the reaction between one or more of the carboxylic functions of said hydroxylated carboxylic acid and a base, the anion of the salt consisting of the hydroxylated carboxylic acid residue and the cation being constituted by the rest of the base.

By hydroxy carboxylic acid derivative, is meant any organic compound comprising at least one carboxylic function selected from ester functions, lactone functions and anhydride functions, and at least one hydroxyl function -OH, primary, secondary or tertiary. Said derivative may further comprise one or more free carboxylic functions. By ester function is meant a function - COOR in which R represents any hydrocarbon group. Such a group may be an alkyl group, for example having from 1 to 20 carbon atoms. Lactone function means a R'-C (O) -OR function in which R and R 'together form an optionally substituted hydrocycled ring, for example having from 3 to 20 carbon atoms. By anhydride function, a function R ^'" -CQ ~ Q ~ CO- R in which R and R' independently of one another represent any grouping hydrocarbon, cyclic or not, for example having 1 to 20 carbon atoms. By salt of a hydroxylated carboxylic acid derivative is meant the compound resulting from the reaction between one or more of the carboxyl functions of said hydroxylated carboxylic acid derivative and a base, the anion of the salt consisting of the remainder of the dicarboxylic acid derivative. hydroxylated carboxylic acid and the cation consisting of the remainder of the base.

A salt according to the invention may comprise several anions.

A passivative compound has the effect of forming a protective film on the treated area, significantly slowing the rate of corrosion of this area relative to what it would be in the absence of this film.

A sequestering compound, or chelating agent, is a compound capable of forming bonds with a metal, generally a transition metal, and in the context of the invention, iron in Fe ³⁺ ferric form, optionally in Fe ² ferrous form. ^÷ , in order to form a stable and insoluble complex in the additive or the product in which the additive is present. Thus complexed, the iron will be protected from oxidation.

Some compounds have both passivating and sequestering properties, such as certain polyphosphates.

These notions are well known to those skilled in the art and it is his responsibility to select one or more suitable compounds.

The various components of a rust converter agent of the invention are hereinafter set forth in detail.

Hydroxylated carboxylic acid salts or hydroxylated carboxylic acid derivative salts

The hydroxylated carboxylic acid or the hydroxylated carboxylic acid derivative of the salt of the invention comprises by definition at least one carboxylic function. It may be in free form -COOH, in ester form, in lactone form or in anhydride form. A derivative may comprise at least one free carboxylic function and at least one carboxylic function chosen from ester, lactone and anhydride functions.

An acid salt whose carboxyl function (s) is free may be a gluconic acid salt, a tartaric acid salt, a citric acid salt or a salt of oxo-gluconic acid. Advantageously, the hydroxylated organic acid is gluconic acid.

An acid derivative salt whose carboxylic function (s) are in lactone form may be a salt of ascorbic acid, a salt of erythorbic acid.

The cation or salts of hydroxylated or deduced derivative organic acid salts may be chosen from any metal cation whose metal is an alkali metal, an alkaline earth metal, a transition metal, a lean metal and from the ammonium ion and primary, secondary or tertiary ammonium ions. Advantageously, the cation or cations are selected from sodium, potassium, calcium, copper, aluminum, ethanolammonium and triethanolammonium ions, the ion derived from ethanolamine.

Preferred hydroxylated or derivatized organic acid salts are selected from the following:

Sodium gluconate, potassium gluconate, ammonium gluconate, monoethanolamine gluconate, triethanolamine gluconate, monoethanolamide gluconate, betaine gluconate, calcium gluconate, aluminum gluconate, copper gluconate

Salts of oxo-gluconic acid;

Salts of tartaric acid;

Salts of ascorbic acid;

Salts of erythorbic acid;

Citric acid salts;

As well as the salts of any acid differing from the above acids by the presence of substituents, such as hydrocarbon groups for example of the alkyl type, such as alkyls having from 1 to 20 carbon atoms, preferably from 1 to 6 carbon atoms. carbon.

In a preferred agent of the invention, the proportion (m / m) of the hydroxylated or deduced derivative organic acid salt or salts ranges from 10 to 25% relative to the mass of said agent. This is essentially to adjust to the amount of rust to neutralize.

Passive and sequestering compounds

The passivating compounds are preferably chosen from sodium nitrite, sodium or potassium phosphate, sodium or potassium tripolyphosphate, monoethanolamine phosphate, triethanolamine phosphate, sodium or potassium hexametaphosphate and phosphonate. sodium or potassium dodecyl phosphonate, sodium or potassium hydroxyphosphonate, sodium or potassium hydroxyethylene diphosphonate, sodium or potassium aminomethylene phosphonate, and ethylene-diamine- sodium or potassium tetraacetate.

The sequestering compounds are preferably chosen from sodium or potassium tripolyphosphate, monoethanolamine phosphate, triethanolamine phosphate, sodium or potassium hexametaphosphate, sodium or potassium phosphonate, sodium or potassium dodecyl phosphonate. sodium or potassium hydroxyphosphonate, sodium or potassium hydroxyethylene diphosphonate, sodium or potassium aminomethylene phosphonate, sodium ethylene diamine tetraacetate and potassium ethylene diamine tetraacetate, which, as indicated above, also have sequestering properties.

According to a preferred embodiment, the proportion (m / m) of the passivating and / or sequestering compound (s) ranges from 5 to 10% relative to the mass of said agent. In a proportion greater than 10%, the compound (s) may affect the formulation of the product in which the additive would be added. For example, in the case of a water-based paint (or water-based paint), an excess of these compounds would produce an immobilization of metal ions present in the paint, such as calcium, by chelation, thus generating lumps . When the proportion of this or these compounds is too low, even if we observe a certain effectiveness of the rust converter additive, it is less.

Solvent

The choice of the solvent is adapted to the hydroxylated or derivatized carboxylic acid salt (s), in that this or these latter will be soluble therein at least partially, advantageously completely. Thus, in the case of a metal cation, the solvent will preferably be aqueous, or even be water; when the cation is an ammonium, the solvent may be aqueous but also organic, preferably a hydroxylated organic solvent, for example an alcohol, such as ethanol. These solvents cited as examples are not intended to limit the scope of the application. It is indeed up to the skilled person to select an appropriate solvent.

The invention also resides in all applications of a rust converter agent as described above.

This agent can indeed be used as an additive to add to coatings of different types, paints, varnishes, coatings, adhesives, sealants, so that they can be applied directly to rust. For example, in aqueous phase coating formulations, the additive is added directly to the coating formulation. It converts the rust and prevents it from going up through the film left by the coating.

The additive is not an anticorrosion agent, it does not prevent the formation of rust consequent on contact with an aqueous medium with a metal, and in an antirust indication, it will be used advantageously in combination with a corrosion inhibitor .

Thus, there is provided an antirust product for the treatment of a rusty or rust-resistant support comprising a rust converter agent according to the invention and a corrosion inhibiting agent. It has been observed that the combination of these two agents allowed to improve the anti-corrosion properties of the corrosion inhibiting agent.

It also provides a product that can be in the form of a paint, a varnish, a coating, an adhesive, a putty. The additive is particularly suitable for aqueous formulations of these products and in this is very advantageous.

The invention also relates to the use of an agent or additive as defined above, for a coating product of a rusty or rust-resistant support, such as a paint, a varnish, an adhesive, a coating, a putty.

When applied to a rusted metal, treatment with such a product converts rust, protects the metal from further oxidation, and provides a primer capable of retaining rust already formed on the surface of the metal so that it does not go back through the layers of finished product like paint, applied later. If the paint or varnish is in aqueous phase, the agent should preferably be associated with a corrosion inhibitor.

The proportion of additive of the invention in a product can vary according to the nature of the product, the nature of the treatment, the support. By way of illustration, in an aqueous phase paint, a suitable proportion (m / m) oscillates between 2 and 5% relative to the weight of the paint. In another product, it may be higher or lower.

The following examples illustrate formulations of a rust converting agent according to the invention.

Example 1 Formulations of a rust converter according to the invention

In the following formulations, the percentages are expressed by weight relative to the mass of the additive.

1.1) Formulation 1:

Water: 79.5%

Sodium gluconate: 14.5%

Sodium tripolyphosphate: 6%

1.2) Formulation 2:

Water: 65.5%

Sodium gluconate: 24.5%

Sodium tripolyphosphate: 6%

Sodium hexametaphosphate: 4%

1.3) Formulation 3:

Water: 58%

Sodium gluconate: 20.4%

Phosphoric acid: 4.5% Sodium tripolyphosphate: 5%

Sodium hexametaphosphate:

Triethanolamine: 8.8

1.4) Formulation 4:

Water: 70.9%

Sodium gluconate: 24.2%

Sodium nitrite: 4.9%

Example 2 Applications and Advantages of a Rust Converter According to the Invention

The formulation illustrated below is Formulation 2 of Example 1.2).

2.1) Rust converter effect in a pretreatment

A rusty steel support is divided into three zones, among which a first is pretreated by a rust converter of the invention, a second is pretreated by a rust converter based on tannic acid, the third is not pretreated .

Then, a layer of acrylic-type white paint is applied to each of the three zones.

It is observed that the first zone is covered perfectly and homogeneously by the paint.

The other two areas have rust spots resulting from rust rising after application of the paint layer.

2.2) Rust converter effect of an agent of the invention incorporated into a paint

A rusty steel support is divided into three zones, of which a first is coated with a layer of a paint of the invention which contains a rust converting agent of the invention, a second is coated with a coating of a paint containing a rust converter based on tannic acid, the third is coated with a coat of paint containing no rust converter.

The second zone is darkened by tannic acid and has rust spots that have migrated to the surface of the layer. The third zone is white but has rust spots that have migrated to the surface of the layer.

These tests demonstrate the effectiveness of a rust converting agent of the invention with respect to the known agents and furthermore demonstrate that it can be incorporated into any product, without its rust converter properties being altered, but also without modifying the properties of the product in which it is incorporated.

Claims

Rust converting additive consisting of one or more salts of hydroxylated organic acid or of a hydroxylated organic acid derivative, one or more passivating compounds, and a solvent, characterized in that the hydroxylated organic acid or acids or or said derivatives are chosen from hydroxylated carboxylic acids and their derivatives, different from tannic acid, and whose carboxylic functions or functions are chosen by free carboxylic functions, ester functions, lactone functions and anhydride functions, and in that the one or more passivating compounds are chosen from sodium nitrite, sodium or potassium phosphate, sodium or potassium tripolyphosphate, monoethanolamine phosphate, triethanolamine phosphate or sodium or potassium hexametaphosphate. , sodium or potassium phosphonate, sodium or potassium dodecyl phosphonate, sodium or potassium hydroxyphosphonate, hydrosodium sodium or potassium oxyethylene diphosphonate, sodium or potassium aminomethylene phosphonate, sodium or potassium ethylene-diamine tetraacetate.

2. Additive according to claim 1, characterized in that the hydroxylated organic acid or acids or derivatives of said hydroxylated or derived carboxylic acid salts have one or more free carboxylic functions, such as gluconic acid, tartaric acid, sodium hydroxide and the like. citric acid, oxo-gluconic acid.

3. Additive according to claim 1 or 2, characterized in that the hydroxylated organic acid is gluconic acid.

4. Additive according to any one of the preceding claims, characterized in that the hydroxylated organic acid derivative (s) of said salts of hydroxylated organic acid derivatives have one or more carboxylic functions chosen from lactone functions, such as ascorbic acid and erythorbic acid.

5. Additive according to any one of the preceding claims, characterized in that the cation or salts of hydroxylated organic acid or a derivative, are chosen from metal cations whose metal is an alkali metal, an alkaline metal. -terreux, a transition metal, a meta l l poor and among the ion a mmonium and ammonium ions primary, secondary or tertiary.

6. Additive according to claim 5, characterized in that the cation or cations are selected from sodium ions, potassium, calcium, copper, aluminum, ethanolammonium, triethanolammonium, the ion from ethanolamine.

7. Additive according to any one of the preceding claims, characterized in that it comprises one or sequestering compounds are chosen pa rmi the sodium or potassium tripolyphosphate, monoethanolamine phosphate, triethanolamine phosphate, sodium or potassium hexametaphosphate, sodium or potassium phosphonate, sodium or potassium dodecyl phosphonate, sodium hydroxyphosphonate or potassium, sodium or potassium hydroxyethylene diphosphonate, sodium or potassium aminomethylene phosphonate, sodium ethylene diamine tetraacetate and potassium ethylene diamine tetraacetate.

8. Additive according to any one of the preceding claims, characterized in that the proportion (m / m) of the hydroxylated or deduced derivative organic acid salt or salts ranges from 10 to 25% relative to the mass of said additive.

9. Additive according to any one of the preceding claims, characterized in that the proportion (m / m) of the passivating compound (s) and / or sequestering (s) ranges from 5 to 10% relative to the mass of said additive.

An anti-rust product for treating a rusted or rust-resistant substrate comprising a rust converter additive according to any one of claims 1 to 9 and a corrosion inhibiting agent.

11. A product for coating a rusted or rust-resistant support comprising a rust-converting additive according to any one of claims 1 to 9 or an antirust product according to claim 10.

12. Product according to claim 11, characterized in that it is a paint, a varnish, an adhesive, a coating, a putty.

13. Product according to claim 11 or 12, characterized in that said product is in aqueous formulation.

14. Use of an additive as defined in any one of claims 1 to 9, for a coating product of a rusty or rust-resistant support, such as a paint, a varnish, a glue, a coating , a putty.