RU2418102C1 - Inhibitor of steel corrosion and procedure for its production - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: composition contains, wt %: poly-acryl-amide-gel 0.01-0.02, modified bentonite with contents of montmoryllonite 80 % and over 0.1-0.5 and water - the rest. The procedure for production of inhibitor consists in introducing solution of water suspension of modified bentonite of concentration 2-20 wt % into concentrated water solution of poly-acryl-gel of 0.6-2.5 concentration at operating mixer and at rate of supply not more, than 2 l/min. Calculated amount of water is added into produced mass and is mixed during 3-5 min. If necessary, in field conditions water can be added directly before inhibitor usage. Insignificant concentrations of general access non-toxic components are present in the composition. The finished product is referred to low-hazard bio-de-composed substances.

EFFECT: high protective properties of steel items from corrosion.

2 cl, 1 tbl

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. 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), allowing to organize 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 the specified technical solution, the substance — a corrosion inhibitor of 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 of 6000 (PEG 6000).

This inhibitor, when applied to a steel product, provides a high degree of protection and also reduces the corrosion rate.

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) the composition is prepared in a relatively narrow temperature range (18-22 ° C);

3) it takes a long time for swelling and mixing of the components;

4) a relatively high concentration of components;

5) multicomponent composition.

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 of water and the resulting mixture is stirred for 10-15 min.

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:

1) the simplification of the technology of preparation of the inhibitor due to the exclusion of operations for temperature control;

2) reducing the time of preparation of the solution;

3) the possibility of preparing a concentrated solution of the inhibitor with its subsequent dilution to the desired concentration immediately before use;

4) reducing the consumption of reagents for surface inhibition, improving the hygienic and environmental properties of the composition by reducing the concentration of components;

5) reduction of internal friction during pumping and application of the inhibitor due to the use of a water-soluble polymer with a high molecular weight.

6) a decrease in the number of inhibitor components to three.

The essence of the group of inventions

The specified single technical result in the implementation of the group of inventions regarding the substance is achieved by the fact that in the known steel corrosion inhibitor based on a water-soluble polymer and bentonite clay, a polyacrylamide gel is used as a water-soluble polymer, and modified bentonite with a content of montmorillonite of 80% is used as a bentonite clay more in the following ratio of components, wt.%:

Polyacrylamide gel 0.01-0.2 Modified Bentonite 0.1-0.5 Water rest

Polyacrylamide gel is an intermediate product of the radical polymerization of acrylamide, which is a concentrated solution (5-10% wt.) Of polyacrylamide with a molecular weight of (4-5) · 10 ⁶ in water. Polyacrylamide gel is easily soluble in water and, in addition, has slightly alkaline properties (pH 8-10) and, therefore, there is no need to use soda to control alkaline properties. In addition, the molecular weight of the polyacrylamide gel is in the most preferred molecular weight region for carrying out the invention, and this product is cheaper.

In addition, the proposed composition used modified bentonite with a high content of the main active ingredient - the mineral montmorillonite (more than 80%, while in ordinary bentonites its content does not exceed 50%). In modified bentonite, the size of clay particles is reduced to 1-100 nm and the swelling is improved, which provides ease of dissolution, increased sedimentation stability of the suspension, facilitating and reducing the time for preparing solutions. The higher cost of modified bentonite (about 1.5-2 times) compared with bentonite in the prototype is offset by its lower content (about 5 times).

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 use of a polymer with a high molecular weight makes it possible to significantly, 5-10 times, reduce the required amount (concentration) of both the polymer itself and other components. A decrease in the concentration of components also becomes possible due to the simultaneous use of modified bentonite, where the proportion of the main active substance, montmorillonite mineral, reaches 80% or more.

It is possible to achieve the optimal ratio between the components with a simultaneous decrease in their quantity necessary to achieve the desired protective effect. The number of inhibitor components is reduced to a minimum (three, including water).

In addition, the ratios of these components in the known final product and the proposed product vary significantly. Compare:

Prototype The ratio of components, wt.% Product Offered Polyoxyethylene with a molecular weight of 6 · 10 ³ 0.001-0.1 0.01-0.2 (0.0005-0.01 per dry matter) Polyacrylamide gel (molecular weight (4-5) · 10 ⁶ ) Bentonite clay 0.5-4.0 0.1-0.5 Modified Bentonite Soda ash 0.1-1.0 0 Absent

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 its required amount to obtain the final product (5-8 times in terms of dry matter);

- there is no need for soda ash. This is due to the fact that the polyacrylamide gel already has slightly alkaline properties, a pH of about 8-10.

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 in low concentrations improves the hydrodynamic characteristics of the inhibitor solution, which 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 additional safety measures.

The specified single technical result in the implementation of the group of inventions in relation to the method is achieved by the fact that in the known method for producing a corrosion inhibitor of steel based on a water-soluble polymer and bentonite clay, a concentrated aqueous solution of a water-soluble polymer, which is used as a polyacrylamide gel, is loaded into a container with a concentration of 0.6-2.5 wt.%, then the process is carried out with the stirrer working, then a solution of an aqueous suspension of bentonite hl is introduced at a rate of not more than 2 l / min foreign substances, which is used as a modified bentonite with a concentration of 2-20 wt.%, then add the calculated amount of water and the resulting mass is stirred for 3-5 minutes.

The composition of the material is formed in such a way that during its manufacture there is no direct dependence on the temperature regime. 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 generally available inexpensive and 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 to which the claimed group of inventions is aimed is to use publicly available components:

a water-soluble polymer - polyacrylamide gel with a molecular weight of (4-5) · 10 ⁶ and modified bentonite with a content of montmorillonite from 80% or more, and in small quantities, and simplification of the technology (method) for obtaining the final product that does not require special equipment.

The implementation of the invention

Steel corrosion inhibitor

A steel corrosion inhibitor based on a water-soluble polymer and bentonite clay, in which according to the invention polyacrylamide gel is used as a water-soluble polymer, and modified bentonite with a content of montmorillonite of 80% or more is used as a bentonite clay, it contains the following components, wt.%:

Polyacryamide Gel 0.01-0.2 Modified Bentonite 0.1-0.5 Water rest.

The presence in the polymer solution - polyacrylamide with a high degree of polymerization and modified bentonite clay with a high content of montmorillonite provide aggregative stability of the obtained composition (sedimentation-resistant colloidal system) with the necessary rheological properties. Due to the fact that both components have slightly alkaline properties (pH 8-10), the presence of soda ash is not required.

In the indicated pH range, the long and polar molecules of the used polymer are straightened in the 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 stabilization quality 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 steel corrosion inhibitor:

1) allows you to get an inexpensive tool based on generally available components, and their quantitative composition and concentration are minimized;

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

3) the composition has a number of new positive qualities:

- resistant to thermal degradation and mechanical degradation;

- it can be prepared in advance in a concentrated form;

- it is efficient in a wide temperature range;

- has 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

When implementing the method for producing a corrosion inhibitor of steel based on a water-soluble polymer and bentonite clay according to the invention, a concentrated aqueous solution of a water-soluble polymer, which is used as a polyacrylamide gel, with a concentration of 0.6-2.5 wt.%, Is loaded into a container equipped with a stirrer then the process is carried out with the stirrer working. Then, with a speed of not more than 2 l / min, a solution of an aqueous suspension of bentonite clay is introduced, which is used as a modified bentonite with a concentration of 2-20 wt.%, Then the calculated amount of water is added and the resulting mass is stirred for 3-5 minutes.

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 an inhibitor

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

In two separate containers of 120 l and 60 l, concentrated solutions of the starting components are preliminarily prepared. 0.4 kg of polyacrylamide gel with a molecular weight of 4 · 10 ⁶ and a concentration of 5 wt.% (For example, Ammonia brand TU 6-01-1049-92) and 49.6 kg are loaded into a first container of 120 liters with stirring water (we get 50 kg of a 0.8% solution of polyacrylamide gel). 3.0 kg of modified bentonite clay with montmorillonite content of more than 80% (for example, Bentocon grade TU 5751-002-58156178-02) and 47.0 kg of water (we get 50 kg of 6% are loaded into a second container of 60 liters with stirring) modified bentonite solution).

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 mixed until smooth for 3-5 minutes.

The result is 100 kg of a concentrated solution of the inhibitor, 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 polyoxyethylene and bentonite in the preparation of the concentrate, however, 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 gel 0.04 wt.%, Modified bentonite 0.3 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 inventive 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 example (embodiment) of the invention 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 gel is used as a water-soluble polymer, and modified bentonite with a content of montmorillonite of 80% or more is used as a bentonite clay in the following ratio, wt.%:
polyacrylamide gel 0.01-0.2 modified bentonite 0.1-0.5 water rest 2. A method of producing 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 0.6- polyacrylamide gel, into a container equipped with a stirrer. 2.5 wt.%, And then with a working stirrer with a speed of not more than 2 l / min, a solution of an aqueous suspension of bentonite clay is introduced, which is used as a modified bentonite with a content of montmorillonite of 80% or more with a concentration of 2-2 0 wt.%, Then add the calculated amount of water and the resulting mass is stirred for 3-5 minutes