RU2418101C1 - Inhibitor of steel corrosion and procedure for its production - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: inhibitor contains, wt %: poly-acryl-amide with molecular weight 10⁴-10⁷ 0.0005-0.01; modified bentonite with contents of montmoryllonite 80% and over 0.1-0.5; soda ash 0.01-0.02 and water - the rest. The procedure consists in loading concentrated water solution of water soluble polymer corresponding to poly-acryl-amide of molecular weight 10⁴-10⁷ and concentration 0.01-0.2 wt % into a reservoir equipped with a mixer and pH metre. Further, the process is carried out with an operating mixer and concentrated water solution of soda ash is added at concentration 2-4 wt %; pH is brought to 8-9, water suspension solution of modified bentonite clay is introduced at rate not over 2 l/min where contents of montmorillonite is 80% and concentration 1-2 wt %. Produced mass is mixed during 3-5 min and there is added calculated amount of water.

EFFECT: inhibitor possesses high safety and corresponds to bio-decomposed substance with high protective properties of steel items from corrosion.

2 cl, 1 ex

Description

FIELD OF THE INVENTION

The group of inventions relates to the field of steel protection against corrosion and can be used to protect overpasses (railway and automobile bridges) and other metal structures or structures.

State of the art

The known composition of the protection of metals from corrosion based on chromates and phosphates with the introduction of salts of amines and organic acids with the addition of surfactants (ed. Certificate of the USSR No. 280163, C23F 11/08, 1972).

The disadvantages of the known composition include the complexity of the composition and the complexity of its preparation, as well as the high consumption of salts, which leads to the high cost of this method of protecting the metal from corrosion.

In addition, the components used are chemically active substances and require special protective measures for their use, as well as special expensive equipment.

Also known is the composition of a metal corrosion inhibitor based on water-soluble polymers, including a water-soluble polyelectrolyte, which is obtained by polymerization of the quaternary ammonium salt of 1,2-dimethyl-5-vinylpyridinium methyl sulfate in an aqueous medium in the presence of a redox initiator β-hydroxypropyl tert-butyl peroxide (patent RU32026565 11/173, 04.20.2003, bull. No. 11). The inhibitory effect of the known inhibitor is that, being adsorbed on the surface of the metal, it forms a thin protective film, which prevents the occurrence of redox processes.

The substance used is inaccessible and expensive, and the method of its “transformation” (production) into a metal corrosion inhibitor is labor-consuming, since it requires the organization of special production and special equipment, which should be attributed to the reasons that prevent its widespread use. In addition, the product is toxic.

There is a need for new effective tools and methods that can provide:

1) a high degree of corrosion protection of metals when using inexpensive publicly available ingredients manufactured by the domestic industry;

2) at the same time significantly reduce labor costs for its production;

3) to simplify the technology of its receipt (preparation) to allow organizing its production (receipt) directly on the spot (processing, for example, a railway bridge);

4) to achieve environmental safety when using an inhibitor in the field;

5) reduce energy consumption in the production and application of the inhibitor;

6) reduce the cost of the entire technological process of inhibition.

The prerequisites for the creation of the present invention that solves the above triune problem (composition, preparation method, application method) were laid down in RU patent No. 2353709. The specified technical solution is the closest in technical essence and the achieved effect to the proposed and we have chosen for the prototype.

In a known technical solution, a corrosion inhibitor of a steel based on a water-soluble polymer contains bentonite clay, and polyoxyethylene is used as a water-soluble polymer in the following ratio, wt.%:

Polyoxyethylene 0.001-0.1 Bentonite clay 0.5-4.0 Soda ash 0.1-1.0 Water rest

This composition uses a water-soluble polymer (polyoxyethylene) with a low molecular weight equal to 6 · 10 ³ (grade PEG 6000).

Its disadvantages include the following:

1) the finished inhibitor is sensitive to changes in external conditions (temperature), which can lead to its irreversible coagulation with loss of inhibitory properties and difficulties in field use;

2) it has insufficient stabilizing (increasing sedimentation stability) effect, in connection with which its required amount increases;

3) a relatively high concentration of components.

In the known method for producing a corrosion inhibitor of steel based on a water-soluble polymer in an aqueous medium, an aqueous polymer solution, using polyoxyethylene with a concentration of 0.9-1.0 wt.%, Is loaded into a container equipped with a stirrer and a pH meter, then the process they are carried out with the stirrer operating and at 18-22 ° C, then a solution of soda ash with a concentration of 0.9-1.0 wt.% is introduced and the pH is adjusted to 8-9, after which a solution of an aqueous bentonite suspension is introduced at a rate of 1 l / min clay with a concentration of 5-10 wt.%, then add the calculated amount water and the resulting mass are mixed for 10-15 minutes.

The described method meets the requirements for obtaining an inhibitor of a given effectiveness. However, the practical implementation of the method, especially in the field, is fraught with a number of difficulties:

1) it is required to strictly control the temperature of the process, and it also takes a relatively long time to prepare the components and mix the solution, and any violation of the technology inevitably leads to irreversible coagulation of bentonite;

2) it is not possible to pre-prepare the inhibitor in concentrated form, so that before use it can only be diluted with water;

3) special equipment with temperature control is required;

4) low hydrodynamic properties of the composition, making it difficult to apply the inhibitor.

The technical result of the group of inventions is the elimination of these disadvantages.

As a brief summary of the nature of the group of inventions, it should be noted that the achieved technical result is provided by using a generally available water-soluble polymer - polyacrylamide with a high molecular weight of the order of 10 ⁴ -10 ⁷ - and modified bentonite with a content of montmorillonite of at least 80%, which can reduce the concentration of the components of the composition, and to simplify the method of obtaining the final product, as well as to improve the method of applying the latter on the treated surface t reduce internal friction when pumping a high pressure pump.

Moreover, as we see, the proposed invention are interconnected by a single inventive concept.

The essence of the group of inventions

The specified single technical result in the implementation of the group of inventions with respect to the substance is achieved in that in the known steel corrosion inhibitor based on a water-soluble polymer of polyoxyethylene and bentonite clay, a polyacrylamide with a molecular weight of 10 ⁴ -10 ^{7 is} used as a water-soluble polymer, and a modified bentonite clay is used bentonite with a content of montmorillonite of 80% or more in the following ratio of components, wt.%:

Polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ 0.0005-0.01 Modified Bentonite 0.1-0.5 Soda ash 0.01-0.02 Water rest

In contrast to the prototype, in which polyoxyethylene with a small molecular weight of 6 · 10 ^{3 is} used as a water-soluble polymer, in the present invention, polyacrylamide with a high molecular weight of 10 ⁴ -10 ⁷ is used instead.

Further, in contrast to the prototype, in which bentonite clay is used as a means of ensuring the sedimentation stability of the suspension, in the present invention, modified bentonite with a high content of the main active ingredient, the mineral montmorillonite (more than 80%, is used instead of it in ordinary bentonite the content does not exceed 50%), which provides increased sedimentation stability of the suspension, rapid swelling and ease of dissolution. Its use also facilitates and saves time for the preparation of the suspension. All this is due to the fact that the size of clay particles in the modified bentonite is 1-100 nm, and the size of the polymer macromolecules exceeds the particle size of bentonite.

In addition, the ratio of these components in the known final product and the proposed product varies significantly.

Compare:

Prototype The ratio of components, wt.% Product Offered Polyoxyethylene with a molecular weight of 6 · 10 ³ 0.001-0.1 0.0005-0.01 Polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ Bentonite clay 0.5-4.0 0.1-0.5 Modified Bentonite Soda ash 0.1-1.0 0.01-0.02 Soda ash

As we see:

- the use of a polymer with a higher molecular weight can significantly (at times) reduce the required amount to obtain the final product (2-10 times);

- the use of modified bentonite also allows you to significantly (at times) reduce the required amount to obtain the final product (5-8 times);

- the need for soda ash is also significantly reduced compared with the prototype, about 50 times. This is due to the fact that the needs of the above components are significantly reduced and, moreover, polyacrylamide already has slightly alkaline properties.

The proposed inhibitor has more stable thermochemical and mechanochemical properties, it can be prepared in concentrated form and diluted with water to the desired concentration immediately before application. In addition, the use of high molecular weight water-soluble polymers improves the hydrodynamic characteristics of the inhibitor solution, which greatly facilitates its application using high pressure pumps. At the same time, low concentrations of the proposed polymer and its biodegradability ensure environmental safety of the production and use of the material in the field without the organization of additional safety measures. The use of higher molecular weight polyacrylamide is also possible. We have tested compositions based on polyacrylamide with a molecular weight of up to 2 · 10 ⁷ . However, the range of molecular weights up to 10 ⁷ is preferable from a practical point of view, since at higher molecular weights the initial concentrated polymer solutions become very viscous, they undergo mechanical destruction and their use in the field is impossible without special equipment.

The technical result of the invention in relation to a method for producing a corrosion inhibitor of steel based on a water-soluble polymer and bentonite clay is achieved by loading a concentrated aqueous solution of a water-soluble polymer, which is used as a polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ , with a concentration of 0.01- 0.2 wt.%, Then the process is carried out with the stirrer working, then a concentrated aqueous solution of soda ash with a concentration of 2-4 wt.% Is introduced and the pH is adjusted to 8-9, after which it is no more than 2 liters / min is introduced a solution of an aqueous suspension of bentonite clay which is used as the modified bentonite with a concentration of 1-2 wt.%, And the resulting mixture is stirred for 3-5 minutes until uniform and then add the calculated amount of water.

The composition of the material is formed in such a way that during its manufacture there is no direct dependence on the temperature regime, as is the case in the prototype (18-22 ° C). The proposed method in comparison with the prototype can significantly simplify and speed up the process by increasing the mixing speed of the components (2 l / min instead of 1 l / min) and reducing the time of their mixing (3-5 minutes instead of 15-20 minutes). As a result, the inhibition process is simplified and cheaper, the environmental consequences of using the inhibitor in the field are improved, and the process of applying it to a steel surface is also simplified.

The process of obtaining an inhibitor can be organized directly at the facility, for example, when processing a railway bridge, or using a mobile unit to obtain a single technical result:

- the use of a commonly available inexpensive water-soluble polymer and other cheap non-toxic components;

- simplification of the technology (method) of obtaining the final product that does not require special equipment;

- the possibility of organizing the production of an inhibitor at the working site of the processed object.

The proposed inventions are interconnected by a single inventive concept, i.e. the single task that the claimed group of inventions aims to solve is to use commonly available components of a water-soluble polymer - polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ - and modified bentonite with a content of montmorillonite from 80% or more, and in small quantities, and simplifying the technology ( method) of obtaining a final product that does not require special equipment.

The implementation of the invention: Steel corrosion inhibitor

The corrosion inhibitor of steel based on a water-soluble polymer, which is used as polyacrylamide, and bentonite clay, which is used as modified bentonite, contains polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ in the following ratio, wt.%:

Polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ 0.0005-0.01 Modified Bentonite 0.1-0.5 Soda ash 0.01-0.02 (up to pH 8-9) Water rest

Modified bentonite is Na-bentonite clay obtained from natural high-quality bentonites after their enrichment and bringing the content of montmorillonite to a level of more than 80%. Modified bentonite is easily and quickly dispersed in water with the formation of a suspension with particles of submicron size.

The presence in the polymer solution — polyacrylamide with a high degree of polymerization — and modified bentonite clay with a high content of montmorillonite ensures the aggregate stability of the obtained composition (sedimentation-resistant colloidal system).

In the indicated pH range, the long and polar molecules of the proposed polymer straighten in solution (at lower values they coagulate in a compact ball, higher values are acceptable but not desirable due to hygienic and environmental requirements), they are easily and firmly adsorbed on the polar surface of montmorillonite microparticles and reliably provide aggregative stability of the resulting colloidal dispersion. In the indicated concentration range, the required level of rheological properties is also provided: pseudoplasticity (thixotropy) at low shear rates and the Newtonian flow under conditions of high-speed dynamic action. Due to the high molecule length of the polymer used (exceeds the particle size of montmorillonite), the polymer itself is required much less, and the quality of stabilization increases (the interparticle distance increases). In addition, the presence of a high molecular weight polymer improves the hydrodynamic characteristics of the flow of the composition (laminar flow at high flow rates) and, therefore, simplifies the process of applying the inhibitor using high pressure pumps.

The claimed combination of essential features, namely the qualitative and quantitative composition of the corrosion inhibitor of steel, provides a technical result and allows you to:

1) get an inexpensive tool based on commonly available components, and their quantitative composition and concentration are minimized;

2) use non-toxic and biodegradable starting components, which is very important from a hygienic and environmental point of view;

3) get a composition that has a number of new positive qualities:

- resistant to thermal degradation and mechanical degradation;

- the possibility of its preparation in advance in a concentrated form;

- operability in a wide temperature range;

- improved hydrodynamic characteristics;

- high adaptability of the use (application) of the inhibitor.

The implementation of the invention: A method of obtaining a corrosion inhibitor of steel

A concentrated aqueous solution of polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ , with a concentration of 0.01-0.2 wt.%, Is loaded into a container equipped with a stirrer and a pH meter, then the process is carried out with the stirrer working, then a concentrated aqueous solution of calcined soda with a concentration of 2-4 wt.% and adjust the pH to 8-9, after which a solution of an aqueous suspension of modified bentonite with a concentration of 1-2 wt.% is introduced at a speed of not more than 2 l / min and the resulting mass is stirred for 3-5 min, then, after a long period of time edstvenno before application, add the calculated amount of water to obtain the desired concentration of the inhibitor.

The resulting composition is within the declared concentration. And the method itself in comparison with the prototype has several advantages:

- reduces the time of preparation of the solution;

- simplifies the technology of preparation of the inhibitor by eliminating the operation for temperature control;

- provides the ability to prepare an inhibitor solution with subsequent dilution with water to the desired concentration immediately before use (the time period from mixing the main components to diluting the concentrated composition with water can be up to several months if stored at positive temperatures and closed).

Thus, the finished product with the specified set of features provides a technical result.

An example of a specific method of obtaining a corrosion inhibitor of steel

To process, for example, one span of a railway bridge, the claimed inhibitor is prepared as follows.

In two separate containers with a volume of 120 l and 60 l, concentrated solutions of the starting components are preliminarily prepared. 40 kg of water are loaded into the first 120 liter container and 0.02 kg of polyacrylamide with a molecular weight of 4 · 10 ⁶ (for example, grade AK-642 TU 6-02-00209912-65-99) is poured with stirring, then an aqueous solution of calcined soda with a concentration of 3 wt.% and adjust the pH to 8-9 (about 10 l of soda solution is required).

3.0 kg of modified bentonite clay with a content of montmorillonite of more than 80% (for example, Bentocon grade TU 5751-002-58156178-02) and 47.0 kg of water are loaded into a second container of 60 liters with stirring.

Then the contents of the container with bentonite are poured with constant stirring at a speed of 2 l / min into the container with polyacrylamide, the composition is stirred until a homogeneous state is 3-5 minutes.

The result is 100 kg of concentrated inhibitor solution, which can be stored closed for a long time. Immediately before applying the inhibitor, the resulting concentrate is poured into a container of 1000 liters, 900 kg of water are added and mixed. You can also use more concentrated solutions of polyacrylamide and modified bentonite in the preparation of the concentrate, but this increases the viscosity of the polymer solution, which complicates the procedure for mixing the components, especially in the field and at low temperatures.

Thus, the resulting composition is within the declared concentrations (polyacrylamide 0.002 wt.%, Bentonite 0.3 wt.%, Soda 0.03 wt.%).

The use of a steel corrosion inhibitor obtained by the described method is as follows.

A liquid inhibitor is applied to steel structures using a high pressure deposit. As a result of the interaction of the liquid jet of the inhibitor with a solid steel surface, a polymer-mineral film with high mechanical and adhesive properties is formed.

Preliminary laboratory tests of the claimed steel corrosion inhibitor at temperatures from -40 to + 45 ° C showed that it provides a degree of protection of 95-99% and reduces the corrosion rate to 0.0001 g / m ² / h.

Thus, the above information indicates the fulfillment of the following set of conditions when using each of the objects of the claimed group of inventions:

- for each claimed invention, in the form described in the corresponding claims, the possibility of its implementation using the means and methods described in the application has been confirmed;

- the claimed technical solutions are capable of ensuring the achievement of the technical result perceived by the applicant.

Therefore, the claimed group of inventions meets the requirement of "industrial applicability".

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information and identification of sources containing information about analogues of the claimed group of inventions for both the object - substance and the object - method, allow us to state that the claimed solutions meet the requirement of "novelty "And" inventive step ".

It should be noted that the advantages of the proposed group of inventions are provided by the presented set of essential features, each of which performs its function, and together, in conjunction, they solve the problem of creating an effective inhibitor from inexpensive components and a simple technology for its preparation, almost anywhere.

The disclosed preferred embodiment (example) is provided by way of illustration and not limitation.

Claims (2)

1. A steel corrosion inhibitor based on a water-soluble polymer and bentonite clay, characterized in that polyacrylamide with a molecular weight of 10 ⁴ -10 ^{7 is} used as a water-soluble polymer, and modified bentonite with a montmorillonite content of 80% or more is used as a bentonite clay in the following ratio components, wt.%:
polyacrylamide with a molecular weight of 10 ⁴ -10 ⁷ 0.0005-0.01 modified bentonite 0.1-0.5 soda ash 0.01-0.02 water rest 2. A method of obtaining a corrosion inhibitor of steel based on a water-soluble polymer and bentonite clay according to claim 1, which consists in loading a concentrated aqueous solution of a water-soluble polymer using a polyacrylamide with a molecular weight of 10 to a container equipped with a stirrer and a pH meter ⁴ -10 ⁷ with a concentration of 0.01-0.2 wt.%, And then with a working stirrer, a concentrated aqueous solution of soda ash with a concentration of 2-4 wt.% Is introduced and the pH is adjusted to 8-9, after which, with a speed of not more 2 l / min inject the solution into discharge slurry of bentonite clay which is used as a modified montmorillonite bentonite with a content of 80% or more at a concentration of 1-2 wt.%, the resulting mixture is stirred for 3-5 minutes and added calculated amount of water.