RU2358036C1 - Method of protecting metal surfaces inhibited with polymer compositions from corrosion and micro-capsules with corrosion inhibitors (versions) - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method consists in applying coating on polymer composition onto metal surface, where polymer composition is made on base of reactive resins, and in successive solidifying; in addition, there is used polymer composition containing micro-capsules with corrosion inhibitor preliminary introduced in micro-capsules from inert sorbent and/or inert sorbent with polymer shell of 1-100 mcm size. The micro-capsule with corrosion inhibitor used for protection of metal surfaces is made out of inert sorbent with polymer shell into pores of which corrosion inhibitor is impregnated and/or the capsule is covered with polymer shell produced by means of sedimentation of film forming substance from solution.

EFFECT: method facilitates upgrading degree of anticorrosion protection of coated metal surface due to continuous dozed release of inhibitor during operation of coating and due to constancy of inhibitor properties in coating; also method increases adhesion and strength of coating, reduces inhibitor consumption and localises selectivity of its effect.

9 cl, 2 dwg, 1 tbl, 4 ex

Description

The present invention relates to the field of corrosion protection of metal surfaces of power, oilfield and chemical equipment and can be used in heat exchangers, pipelines and tanks in contact with aggressive environments.

A known method of corrosion protection of metal surfaces of pipelines and apparatus of the chemical industry, as well as tubes of heat-exchange equipment by applying a polymer compound based on reactive resins with subsequent curing [Golovin VA, Ilyin AB, Kuznets VT, Kublitsky K .V., Schelkov V.A. Corrosion protection and restoration of heat exchange equipment with polymer coatings // Corrosion: materials, protection. 2003. No. 2, p.2-8]. According to this method, the anticorrosion coating is made of a composition comprising, as a polymer binder, a polymer system based on epoxy, phenol-formaldehyde, furan, polyurethane resins (for example, VIKOR-793 TRIO epoxyphenol-furan compound or VIKOR-8095KT NPO epoxy-amine compound) manufactured by NPO.

However, this method of corrosion protection of the surfaces of pipelines, equipment and tubes of heat-exchange equipment does not allow protecting the metal surface when aggressive media penetrate the coating in places of coating chips, cracks, microdefects, and also in places of adhesion defects.

Known anti-corrosion coating [RF patent No. 2251563], made of a composition comprising a polymer binder and hollow microcapsules of glass, ceramics, polymers or mixtures thereof. It is made from a water-suspension composition and contains an aqueous emulsion polymer latex composition containing from 10 to 90 vol.% (Co) polymer selected from the group consisting of acrylate co-polymer, styrene-acrylate copolymer, styrene-butadiene copolymer, polystyrene, butadiene polymer, polyvinyl chloride polymer, polyurethane polymer, vinyl acetate polymer or copolymer or mixtures thereof and from 10 to 90 vol.% a mixture of water and a surfactant. As hollow microspheres, the composition contains a mixture of hollow microspheres with sizes from 10 to 500 μm, selected from the group comprising hollow glass microspheres, hollow ceramic microspheres, hollow polymer microspheres, hollow man-made (ash). The anticorrosion coating additionally contains a corrosion inhibitor (sodium nitrite, sodium benzoate, guanidine chromate, etc.) in amounts traditionally used in such aqueous dispersions. The inhibitor is introduced into the binder. The material with microspheres according to the patent of the Russian Federation No. 2251563 is proposed to be used to improve mainly the thermal insulation qualities of polymer coatings.

This system has all the disadvantages characteristic of the direct introduction of a corrosion inhibitor, namely, the deterioration of adhesion and strength of the finished coating, deactivation and premature consumption of the inhibitor due to its reactions with the components of the polymer base of the compounds during their curing.

Known microcapsules with corrosion inhibitors introduced into them [RF patent No. 2111049] containing a chemical reagent and walls made of gelatin stabilized with an effective amount of a chelating agent, the microcapsules containing 5-80% of a reagent selected from the group comprising a scale inhibitor, an inhibitor corrosion, a biocidal agent, a reagent to limit the presence of solid hydrocarbons, a reagent that carries H ₂ S and / or O ₂ . Such microcapsules are very fragile and can easily be destroyed. With the destruction of microcapsules, a corrosion inhibitor is rapidly released in various sections of oil wells during oil and gas production. The concentration of capsules in the working fluid is from 10 to 80%.

However, hydrophilic and water-soluble polymers (such as gelatin) cannot be used in protective polymer coatings due to the fact that they lead to increased sorption of water by the coating and increase its permeability, and also because of the incompatibility with polymer binders of most types of protective coatings. The consequence of the ease of destruction of the microcapsules is the rapid (volley) release of the corrosion inhibitor, which is good when processing wells, but does not provide the duration of the inhibitor in the coating. In addition, the microcapsules formed by the proposed method do not have the necessary strength and will break down already when the coating is applied, for example, when using the most advanced airless spray method.

The present invention solves the problem of increasing the degree of corrosion protection of the coated metal surface due to:

- prolonged dosed release of the inhibitor during the operation of the coating,

- the properties of the inhibitor in the coating remain unchanged until the coating is completely cured by preventing the reaction of the reactive components of compounds based on oligomers (including epoxy) with the inhibitor,

- increased adhesion and coating strength due to the exclusion of uncontrolled exposure of the inhibitor to the polymer curing process,

- reducing the consumption of the inhibitor and local selectivity of its action.

The problem is solved in that in the method of protecting metal surfaces from corrosion by inhibited polymer compositions by applying polymer compositions based on reactive resins to the metal surface followed by curing of the coating, the polymer composition contains microcapsules with a corrosion inhibitor previously introduced into the microcapsules from an inert sorbent and / or inert sorbent with a polymer shell, having a size of 1-100 microns.

The problem is solved in that in a method of protecting against corrosion of metal surfaces, microcapsules of an inert sorbent and / or inert sorbent with a polymer shell are 10-20 μm in size.

The problem is solved in that the microcapsule with a corrosion inhibitor used to protect metal surfaces is made of an inert sorbent, into the pores of which the corrosion inhibitor is impregnated from the gas phase.

The problem is solved in that the microcapsule with a corrosion inhibitor used to protect metal surfaces is made of an inert sorbent with a polymer shell, into the pores of which a corrosion inhibitor is impregnated, and the polymer shell is obtained by precipitation of a film-forming substance from a solution.

The problem is also solved by the fact that as the sorbent use porous alumina or zeolites of various grades, porous silicon oxide.

The problem is also solved by the fact that as the film-forming substance used is a polymer selected from the group - polyvinyl chloride, polystyrene, polymethyl methacrylate, ethyl cellulose, nitrocellulose, polyvinyl alcohol, polyvinyl acetate.

The problem is also solved by the fact that the coating is applied by airless spraying at high pressures in the spray nozzle.

The problem is also solved by the fact that the coating is applied using a brush or roller in several layers.

The invention is illustrated in figures 1 and 2, where in Fig. 1 presents Al ₂ O ₃ particles with an inhibitor impregnated at a temperature of 120 ° C, and Fig. 2 shows microcapsules of an inhibited sorbent in a polymer shell at a 200-fold increase.

The method of protection against corrosion of metal surfaces is as follows.

To obtain an anticorrosive coating, a polymer composition (compound) is applied onto the metal surface to be protected, containing microcapsules previously obtained by the methods described below (options 1 or 2) with a corrosion inhibitor in an amount of 1 to 20 parts by mass.

Depending on the type of inhibitor, microcapsules with a corrosion inhibitor are introduced either preliminarily into the polymer, or into the hardener, or into the finished mixture of the polymer and hardener. The compound is thoroughly mixed.

The resulting compound is applied to a cleaned metal surface with a brush, roller or spray methods in one or more layers. Due to the high strength of the microcapsules, airless spraying can be used. Dry or cure the coating.

A method of obtaining microcapsules (1 option) containing a corrosion inhibitor, as follows.

The necessary amount of finely dispersed inorganic sorbent (50-90 mass parts) and 10-50 wt. parts of an organic corrosion inhibitor.

Carry out heating at a temperature of 15-20 ° C higher than the melting point or boiling point of the inhibitor, but not higher than the decomposition temperature.

The process is continued until the inhibitor is completely absorbed into the free pore volume of the sorbent. Usually the warm-up time is 3-6 hours.

The resulting powder retains high dispersion and flowability, which allows sieving with the selection of the required fraction.

A method of obtaining a microcapsule with a polymer shell (option 2) containing a corrosion inhibitor is as follows.

At the first stage, microcapsules are obtained from an inorganic sorbent and inhibitor, as in embodiment 1.

In the second stage, the resulting powder is additionally coated with a polymer shell by precipitation from solution.

For this, the obtained (according to option 1) impregnated corrosion inhibitor is dispersed in a 1-5% solution of a film-forming polymer in an organic solvent in an amount of 1 wt.h. microencapsulated inhibitor for 5-20 mass parts of the solution.

Then, with vigorous stirring, pour 100 ml of the mixture into 1000 ml of a 0.1-0.3% aqueous solution of polyvinyl alcohol.

After vigorous short (2-5 min) mixing, the microcapsules are collected at the bottom of the vessel, easily separated by centrifugation or sedimentation, and after drying, they look like particles of various sizes - from 1 to 100 microns.

If necessary, sieving is carried out with the selection of the required fraction.

The following are specific examples of the implementation of the claimed methods.

Example No. 1

Obtaining a microencapsulated corrosion inhibitor

The preparation of a microencapsulated corrosion inhibitor consists in creating a finely dispersed sorbent with an azole and amine corrosion inhibitor impregnated into it. This is done by heating placed in one tank 70 wt. parts of Al ₂ O ₃ powder with 30 wt. parts of a 50% solution of benzotriazole (BTA) in NI-dimethylbenzylamine at a temperature 15-20 ° C higher than the melting point of benzotriazole. The process continues until the inhibitor is completely absorbed into the free pore volume of the sorbent. The resulting powder retains flowability, which is clearly visible in microphotographs.

Obtaining a polymer compound

The preparation of the polymer compound consists in introducing a microencapsulated corrosion inhibitor (MIC) and an amine hardener into the epoxy resin. In example No. 1 in 100 g of low viscosity epoxy resin E-240 injected 16.7 g obtained by the above technology microencapsulated corrosion inhibitor (MIC). Then the mixture is thoroughly mixed and 20 mass parts of the amine hardener are introduced into it.

Coating and curing

The prepared compound is applied to sandblasted plates of steel St-3. Application is carried out with a brush. The coating thickness is 100-120 microns.

Curing of the coating is carried out at a temperature of 25 ± 5 ° C for 7 days.

Example No. 2

Obtaining a microencapsulated corrosion inhibitor

The preparation of a microencapsulated corrosion inhibitor consists in the creation of a finely dispersed sorbent with an azole corrosion inhibitor impregnated from it. This is done by heating placed in one tank 70 wt. parts of Al ₂ O ₃ powder with 30 wt. parts of benzotriazole (BTA) at a temperature of 15-20 ° C higher than the melting point of benzotriazole. The process continues until the inhibitor is completely absorbed into the free pore volume of the sorbent. The resulting powder retains high dispersion and flowability.

Obtaining a polymer compound

The preparation of the polymer compound consists in introducing a microencapsulated corrosion inhibitor (MIC) and hardener into the mixture of reactive resins. In example No. 2 in a mixture of 60 wt.h. epoxy resin ED-20 with 40 parts by weight low viscosity phenoformaldehyde-furan resin RSF-014 injected pre-obtained mixture of 8 wt.h. obtained by the technology described above microencapsulated corrosion inhibitor (MIC) and 35 m.h. ketamine hardener. Then the mixture is thoroughly mixed.

Coating and curing

The prepared compound is applied with a brush to copper-plated sandpaper plates. Application is carried out with a brush. The coating thickness is 100-120 microns.

Curing of the coating is carried out at a temperature of 25 ± 5 ° C for 7 days.

Example No. 3

Obtaining a microencapsulated corrosion inhibitor

Obtaining microencapsulated corrosion inhibitor (MIC) is carried out in two stages. In the first stage, the sorbent powder impregnated with the inhibitor is obtained, and in the second stage, particles of the sorbent with the polymer shell inhibitor are coated.

The impregnation carried out in the first stage is achieved by sintering the zeolite powder with dithio-bis-benzthiazole (altax) or its solution in benzene at a temperature of 120 ° C. This is done by heating 80 wt. parts of zeolite powder with 20 wt. parts of altax. When impregnated, the inhibitor is absorbed into the free pore volume of the sorbent. The obtained impregnated corrosion inhibitor is dispersed in a 2% solution of ethyl cellulose (EC) in methylene chloride in an amount of 10 parts by weight per 100 mass parts of the solution.

In the second stage, with vigorous stirring, pour 100 ml of the mixture into 1000 ml of a 0.2% aqueous solution of polyvinyl alcohol.

After vigorous short (2-5 min) mixing, the microcapsules are collected at the bottom of the vessel, easily separated by centrifugation or sedimentation and, after drying, have the form of particles of various sizes - from 1 to 100 μm (Figure 2).

Obtaining a polymer compound

The preparation of the polymer compound consists in introducing a microencapsulated corrosion inhibitor (MIC) and an amine type hardener into the epoxy resin. In example No. 3 in 100 parts by weight epoxy resin ED-20 is introduced with thorough stirring previously obtained by the above technology microencapsulated corrosion inhibitor (MIC) in an amount of 20 wt. hours, 10 parts by weight amine hardener and 3 parts by weight thinner. Then the mixture is re-mixed.

Coating and curing

The prepared compound is applied to sandblasted plates of steel St-3. The compound is applied by roller. The coating thickness is 120-150 microns.

Curing of the coating is carried out at a temperature of 25 ± 5 ° C for 7 days.

Example No. 4

Obtaining a microencapsulated corrosion inhibitor

Obtaining microencapsulated corrosion inhibitor (MIC) is carried out in two stages. In the first stage, the sorbent powder impregnated with the inhibitor is obtained, and in the second stage, particles of the sorbent with the polymer shell inhibitor are coated.

The impregnation carried out in the first stage is achieved by sintering a silicon oxide powder with benzotriazole (BTA) at a temperature of 120 ° C. This is done by heating 80 wt. parts of silicon oxide powder with 20 wt. parts of benzotriazole. When impregnated, the inhibitor is absorbed into the free pore volume of the sorbent. The obtained impregnated corrosion inhibitor is dispersed in a 2% solution of polymethylmethacrylate (PMMA) in methylene chloride in an amount of 20 parts by weight per 100 mass parts of the solution.

In the second stage, with vigorous stirring, pour 100 ml of the mixture into 1000 ml of a 0.2% aqueous solution of polyvinyl alcohol.

After vigorous short (2-5 min) mixing, the microcapsules are collected at the bottom of the vessel, easily separated by centrifugation or sedimentation and, after drying, have the form of particles of various sizes - from 1 to 100 microns (mainly 10-20 microns). Dried MKIK are fine granular powder of white or light beige color. Fractionation is carried out, isolating a fraction of up to 20 microns.

Obtaining a polymer compound

The preparation of the polymer compound consists in introducing a microencapsulated corrosion inhibitor (MIC) and an amine hardener into the epoxy resin. In example No. 4 in 100 parts by weight DER-330 epoxy resin is injected with thorough stirring the microencapsulated corrosion inhibitor (MIC) previously obtained by the above technology in the amount of 10 parts by weight, 10 parts by weight amine hardener and 5 parts by weight rheological additives and diluent. Then the mixture is re-mixed.

Coating and curing

The prepared compound is applied to sandblasted plates of steel St-3. Application is carried out by airless spray. The coating thickness is 70-100 microns.

Curing of the coating is carried out at a temperature of 25 ± 5 ° C for 7 days, followed by curing at 100 ° C for 6 hours.

The results of comparative tests of corrosion resistance of the coatings obtained according to the present invention, and the results of the corresponding blank experiments are shown in the table.

Table Corrosion Resistance of Coatings Example No. Notes The degree of sub-film corrosion after exposure to 0.3% NaCl for 90 days at 50 ° C Adhesion by the method of trellised incision after exposure to 0.3% NaCl for 90 days at 50 ° C findings Example No. 1 Substrate Steel-3, the coating contains microcapsules with an inhibitor without a shell Less than 5%. The remaining surface of the steel is passivated, retaining its luster 3 points. Peeling 22% of the squares along the notch lines The metal surface under a continuous coating is passivated; in places of breakdown of the film, the corrosion process is inhibited Blank experience for example No. 1 Substrate Steel-3 coating contains microcapsules without inhibitor In a blank experiment - 100%. Continuous Coating Film of Corrosion Products 4 points. In a blank experiment, 90% of the squares completely exfoliated The sample under the coating is completely corroded, the film is easily permeable to chlorides. Example No. 2 The substrate is copper, the coating contains microcapsules with an inhibitor without a shell Less than 5%. The remaining surface of the copper retained its luster 3 points. Delamination of 12% of squares along the notch lines The metal surface under a continuous coating is passivated; in places of breakdown of the film, the corrosion process is inhibited Blank experience for example No. 2 The substrate is copper, the coating contains microcapsules without an inhibitor In a blank experiment - 100%. The entire surface is darkened and covered with a film of corrosion products 4 points. In a blank experiment, 60% of the squares completely exfoliated The sample under the coating corroded, the film is easily permeable to chlorides. Example No. 3 Substrate Steel-3, the coating contains microcapsules with an inhibitor with a shell based on EC + PVA Less than 15%. The remaining surface of the steel is passivated, retaining its luster 3 points. Delamination of 32% of squares along notch lines The metal surface under a continuous coating is passivated; in places of breakdown of the film, the corrosion process is inhibited Idle experience for example No. 3 without IR Substrate Steel-3 coating contains reinforced microcapsules without inhibitor In a blank experiment - 100%. Continuous Coating Film of Corrosion Products 4 points. In a blank experiment, 90% of the squares completely exfoliated The sample under the coating is completely corroded, the film is easily permeable to chlorides. Example No. 4 Steel-3 substrate, the coating contains reinforced silicon oxide microcapsules with an inhibitor with a shell based on PMMA + PVA Matte, firmly adhered to the surface protective film over the entire surface, 2 points (exfoliated less than 5% coverage) The metal surface is passive, adhesion is not impaired, coating integrity is preserved, MIC acts effectively through the pores of the sorbent and the wall of such capsules. Idle experience for example No. 4 Substrate Steel-3, the coating contains unreinforced microcapsules with an inhibitor with a shell based on PMMA + PVA The surface is almost clean, without pitting, but the adhesion is broken, there are air "bubbles" under the coating 4 points (90% of the coating exfoliates) Hollow microcapsules disrupt the continuity of the coating, making it look like foam. However, IR effectively inhibits the corrosion process.

Claims (9)

1. A method of protecting metal surfaces from corrosion by inhibited polymer compositions, comprising applying to the metal surface a coating of a polymer composition based on reactive resins followed by curing, characterized in that they use a polymer composition containing microcapsules with a corrosion inhibitor previously introduced into the microcapsules of inert sorbent and / or inert sorbent with a polymer shell, the sizes of which are 1-100 microns. 2. The method according to claim 1, characterized in that they use a polymer composition containing microcapsules of an inert sorbent and / or inert sorbent with a polymer shell 10-20 μm in size. 3. The method according to claim 1 or 2, characterized in that the coating is applied by airless spraying at high shear loads in the spray nozzle. 4. The method according to claim 1 or 2, characterized in that the coating is applied using a brush or roller in layers. 5. A microcapsule with a corrosion inhibitor used to protect metal surfaces, characterized in that it is made of an inert sorbent, into the pores of which the corrosion inhibitor is impregnated from the gas phase. 6. The microcapsule according to claim 5, characterized in that the porous alumina or zeolites of various grades, porous silicon oxide, are used as an inert sorbent. 7. A microcapsule with a corrosion inhibitor used to protect metal surfaces, characterized in that it is made of an inert sorbent with a polymer shell, into the pores of which a corrosion inhibitor is impregnated, and the polymer shell is obtained by precipitation of a film-forming substance from a solution. 8. The microcapsule according to claim 7, characterized in that the porous alumina or zeolites of various grades, porous silicon oxide, are used as an inert sorbent. 9. The microcapsule according to claim 7, characterized in that as the film-forming substance used is a polymer selected from polyvinyl chloride, polystyrene, polymethyl methacrylate, ethyl cellulose, nitrocellulose, polyvinyl alcohol, polyvinyl acetate.

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