CN111334161A - Flexible self-repairing anticorrosive coating for inner wall of seawater steel pipeline and preparation method thereof - Google Patents

Abstract

The invention relates to the field of corrosion prevention, in particular to a flexible self-repairing corrosion prevention matched coating for the inner wall of a seawater steel pipeline and a preparation method thereof. The matched coating consists of a primer and a finish; wherein, the priming paint comprises, by weight, 0.5-2% of epoxy microcapsule, 35-45% of pigment filler A, 10-20% of organic solvent A, 1-4.5% of auxiliary agent A, 20-30% of curing agent A and the balance of organic resin A; the finishing coat comprises, by weight, 1.5-4.5% of toughened modified resin, 40-45% of pigment and filler B, 10-15% of organic solvent B, 1-4.5% of auxiliary agent B, 15-20% of curing agent B and the balance organic resin B. Compared with other similar coatings, the coating has the advantages of good flexibility, peeling resistance, impact resistance, salt spray resistance and other anticorrosion performances after being cured into a film, simple process and low cost.

Description

Flexible self-repairing anticorrosive coating for inner wall of seawater steel pipeline and preparation method thereof

Technical Field

The invention relates to the field of corrosion prevention, in particular to a flexible self-repairing corrosion prevention matched coating for the inner wall of a seawater steel pipeline and a preparation method thereof.

Background

The seawater steel pipeline is in a special environment and has higher requirements on coating materials. When the common coating is applied to the environment, the defects of short service life and frequent maintenance are mostly existed. The reason is that on one hand, under the severe marine environment, the coating is easy to be corroded by chloride ions and the like for a long time, and bubbles are peeled off; on the other hand, the coating is easy to crack and further lose efficacy under the influence of seawater scouring; moreover, the interference of stray current generated by the cathodic protection of the outer wall of the steel pipeline is avoided, and the coating is easy to peel off by a large-area cathode. Because the repair construction of the coating on the inner wall of the pipeline is difficult, the development of a coating system which can self-repair, resist scouring and has the cathode stripping resistance is very important for improving the protective performance of the coating, prolonging the repair period of the coating and realizing the long-acting anticorrosion protection of the substrate.

Disclosure of Invention

Aiming at the defects of the existing coating, the invention aims to provide a flexible self-repairing anticorrosion matched coating for the inner wall of a seawater steel pipeline and a preparation method thereof.

In order to realize the purpose of the invention, the invention adopts the technical scheme that:

a flexible self-repairing anticorrosion matched coating for the inner wall of a seawater steel pipeline comprises a primer and a finish; wherein, the primer comprises, by weight, 0.5-2% of epoxy microcapsule, 35-45% of pigment filler A, 10-20% of organic solvent A, 1-4.5% of auxiliary agent A, 20-30% of curing agent A, and the balance of organic resin A; the finishing coat comprises, by weight, 0.5-2% of toughening modified resin, 40-45% of pigment filler B, 10-15 parts of organic solvent B, 1-4.5% of auxiliary agent B, 15-20% of curing agent B and the balance organic resin B.

The organic resin A is epoxy resin with the molecular weight of about 380-400; the pigment filler A is one or more of zinc phosphate, aluminum powder, iron oxide red, talcum powder and white carbon black; the curing agent A is an amine curing agent, such as polyamide TL-285, modified amine curing agent 9593, and the like.

The epoxy microcapsule is of a core-shell structure; wherein, the core is epoxy resin added with corrosion inhibitor, and the shell layer is urea-formaldehyde resin prepolymer; the corrosion inhibitor is one or more of carboxylic acid and/or carboxylic acid derivatives. Wherein the dosage ratio of the core shell to the shell is 0.8-1.3: 1; the addition amount of the corrosion inhibitor is 0.5-1.0% of the mass of the epoxy microcapsule, and the molecular weight of the epoxy resin is 440-460.

The corrosion inhibitor is a carboxylic acid corrosion inhibitor, and the carboxyl terminal of the corrosion inhibitor is connected with a functional group; the functional group is one or more of carboxyl, phosphonic acid group and hydroxyl; the corrosion inhibitor mainly comprises 2-phosphoric butane-1, 2, 4-tricarboxylic acid, dodecenyl-I-diacid, oleophthalein sarcosine and the like.

The epoxy microcapsule

1) Synthesis of urea resin prepolymer: mixing urea and formaldehyde solution according to the mass ratio of 1:2-1: 1; and adjusting the pH value of the mixed solution to 8-9, heating to 70-75 ℃ in a water bath, reacting for 1-2 hours, and cooling to room temperature for later use.

2) Preparing a microcapsule core material: epoxy resin, trimethylolpropane triglycidyl ether and a corrosion inhibitor are mixed according to the mass ratio of 4.5-5: 1-1.5: 0.1 to 0.2, and emulsifying and dispersing for 10 to 15 minutes to obtain the emulsion.

3) Synthesis of epoxy resin microcapsules: dissolving ionized water and sodium dodecyl benzene sulfonate in deionized water, adding the emulsion of the microcapsule core material obtained in the step 2) after dissolving, and adding the urea resin prepolymer and the urea resin curing accelerator in the step 1) according to the weight ratio of 1-2: 1-1:2, mixing, adjusting the pH value of the system to 5-6, heating to 60-65 ℃, reacting for 3-4h, and filtering to obtain the microcapsule.

The toughening modified resin is epoxy resin toughened and modified by polyurethane, and accounts for 3-7 wt% of the total amount of the finish paint.

Preparation of the toughened modified resin

1) Synthesis of a polyurethane prepolymer: and (2) carrying out vacuum dehydration on polyether polyol (with the molecular weight of 800-2000) under the protection of nitrogen, cooling to 30-40 ℃, adding hexamethylene diisocyanate, heating the system to 80-85 ℃ under the protection of nitrogen, and reacting for 3h to obtain the prepolymer. Wherein the mass ratio of the polyether polyol to the hexamethylene diisocyanate is 2-3: 1-2.

2) Synthesis of polyurethane toughened epoxy resin: adding epoxy resin with the molecular weight of 380-400 into the reacted prepolymer, reacting for 1-2h at the temperature of 80-85 ℃, adding dibutyltin dilaurate, continuing to react for 0.5-1h, vacuumizing and defoaming until no bubble exists, and cooling to 30-40 ℃ to obtain the toughening modified resin.

The organic resin B is epoxy resin with the molecular weight of about 900-; the pigment filler B is one or more of mica iron oxide, calcium carbonate, talcum powder and titanium dioxide; the curing agent B is amine curing agent, such as polyamide 650, polyether amine T403 and D230, etc.

The auxiliary agent A is a leveling agent accounting for 0.5-1% of the mass of the primer, a defoaming agent accounting for 1-1.5% of the mass of the primer and a dispersing agent accounting for 1-2% of the mass of the primer;

the auxiliary agent B is a leveling agent accounting for 0.5-1% of the mass of the finish paint, a defoaming agent accounting for 1-1.5% of the mass of the finish paint, a dispersing agent accounting for 1-2% of the mass of the finish paint and a thickening agent accounting for 1-2% of the mass of the finish paint;

the organic solvent A and the organic solvent B are methyl isobutyl ketone and xylene in a mass ratio of 2:1-1: 2.

A preparation method of a flexible self-repairing anticorrosion matched coating for the inner wall of a seawater steel pipeline comprises the steps of coating an epoxy microcapsule primer coating on the surface of a metal in a scraping manner, and then coating a finish coating of toughened modified resin on the surface of the primer coating in a scraping manner to form a flexible modified finish coating; wherein the thickness of the primer coating is more than or equal to 250 mu m, and the thickness of the finish coating is more than or equal to 200 mu m.

Preparing the primer coating:

adding the epoxy microcapsules into the organic solvent A according to the proportion, uniformly dispersing, sequentially adding part of the organic resin A, the pigment filler A, the dispersing agent and the defoaming agent into the dispersion liquid, uniformly stirring and dispersing to obtain a dispersion body for later use;

mixing the obtained dispersoid with the residual organic resin A, then adding the leveling agent, fully and uniformly stirring, then adding the curing agent A, and drying to obtain the primer coating;

the preparation of the finish coat comprises the following steps:

adding the toughening modified resin into the organic solvent B according to the proportion, uniformly dispersing, sequentially adding part of the organic resin B, the pigment and filler B, the dispersing agent and the defoaming agent into the dispersion liquid, uniformly stirring and dispersing to obtain a dispersion for later use;

and mixing the obtained dispersion with the rest of the organic resin B, then adding the thickening agent and the leveling agent, fully and uniformly stirring, then adding the curing agent B, and drying to obtain the finish coat.

The metal is a water pipeline or chemical equipment.

The invention has the advantages that:

the coating comprises epoxy microcapsules, a corrosion inhibitor, toughening modified epoxy resin and organic resin. The corrosion inhibitor takes the epoxy microcapsule as a carrier, is uniformly dispersed into organic resin to be cured into a film, not only improves the corrosion resistance of the coating, but also improves the adhesive force between the coating and the matrix. The toughening and toughening modified resin in the invention forms a cross-linked network structure in the organic resin, thereby improving the toughness and the anti-scouring performance of the coating and reducing the damage probability of the coating. Compared with other similar coatings, the coating provided by the invention can prolong the damage period of the coating after being cured into a film, has the corrosion resistance such as saline water penetration resistance, high adhesive force, good flexibility, cathodic disbonding resistance and the like, and is simple in process and low in cost.

Drawings

FIG. 1 is a microstructure view of an epoxy microcapsule according to an embodiment of the present invention;

FIG. 2 is an infrared spectrum of an epoxy microcapsule according to an embodiment of the present invention;

FIG. 3 provides a graph comparing tensile properties of modified and unmodified resins according to examples of the present invention;

FIG. 4 is a photograph of the surface topography of a composite coating provided by an embodiment of the present invention after 8 months under salt spray conditions;

FIG. 5 is a photograph of the surface topography of a pure epoxy coating provided by an embodiment of the present invention after 8 months under salt spray conditions;

FIG. 6 is a comparison graph of AC impedance spectra of a composite coating and a pure epoxy coating provided by an embodiment of the present invention after 4 months of salt spray acceleration test;

FIG. 7 is a surface topography diagram of a test piece of the composite coating provided by the embodiment of the invention after being soaked in 3.5% NaCl saline for 60 days at a voltage of-1.5 v and a temperature of 60 DEG C

FIG. 8 is a picture of a sample after a bending resistance test of the composite coating provided by the embodiment of the invention

FIG. 9 is a picture of a sample after an impact test of the composite coating provided by the embodiment of the invention

Detailed Description

The flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline, which is obtained through extensive and intensive research, comprises the primer and the finish, has high bonding force with a metal substrate and good compatibility, has good stripping resistance and chloride ion permeation resistance after being cured into a film, is low in cost, and provides a simple process for metal anticorrosion.

The primer is prepared by uniformly dispersing epoxy microcapsules into organic resin, then curing the organic resin and a curing agent to form a film, and the finish paint is prepared by uniformly dispersing the flexibility-enhancing and toughening-modified resin, the organic resin, a pigment, a filler and an auxiliary agent, and then curing the mixture and the curing agent to form a film, so that the coating has good corrosion resistance and corrosion resistance after being damaged. The epoxy microcapsule is used as a carrier of the corrosion inhibitor, and the corrosion inhibitor is released after crosslinking in the resin, so that the corrosion resistance of the base material is improved, the flexibility of the coating can be improved by the toughened and modified resin, and the probability of damage of the coating due to external force is reduced. Compared with other similar coatings, the coating has the advantages of good flexibility, peeling resistance, impact resistance, salt spray resistance and other anticorrosion performances after being cured into a film, simple process and low cost.

The substances provided by the invention can be synthesized by using commercially available raw materials or conventional chemical conversion modes. Wherein the leveling agent is one of BYK300, BYK310, BYK388, BYK331, RH-T1006N, RH-T1023, RH-T1033A, RH-T1045, RH-T1008, RH-T308, RH-T1057, RH-T1010 and RH-T1245, the defoaming agent is one of BYK051, BYK052, BYK053, BYK054, BYK056, BYK057, BYK065, BYK077, BYK066N, BYK065, BYK085 and BYK0141, the dispersing agent is one of BYK-P104S, BYK-163, BYK-110, BYK-161, BYK-164, BYK-111, BYK104S, DISPERBYRBYRBYRBYRBYRYK-160, DISPERK-161, DISPERYK-162, MIK-1958 and RAHL 139, MIK-R1210 and MIR-R1210.

Other aspects of the invention will be apparent to those skilled in the art in view of the disclosure herein.

The following examples are presented to further illustrate embodiments of the present invention, and it should be understood that the embodiments described herein are for purposes of illustration and explanation only and are not intended to limit the invention.

Unless defined or stated otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention.

EXAMPLE 1 preparation of epoxy microcapsules

1) Synthesis of urea resin prepolymer: mixing urea and formaldehyde solution according to the mass ratio of 1: 2; wherein the mass concentration of the formaldehyde solution is 37 percent, the mass concentration of the urea is 25g, and the mass concentration of the formaldehyde solution is 50 g; regulating the pH value of the mixed solution to 8-9 by using triethanolamine, adding the mixed solution into a three-neck flask, regulating the stirring speed, heating the mixed solution to 70 ℃ in a water bath, and cooling the mixed solution to room temperature for later use after reacting for 1 hour.

2) Preparing a microcapsule core material: 50g of bisphenol A type E-44 epoxy resin is weighed, 10g of trimethylolpropane triglycidyl ether is mixed with 1g of 2-phosphoric acid butane-1, 2, 4-tricarboxylic acid (corrosion inhibitor) and then emulsified by a high-speed shearing emulsifying machine after being mixed, and the mixture is dispersed for 10 minutes to obtain the emulsion for standby.

3) Synthesis of epoxy resin microcapsules: weighing 100g of deionized water, adding 2.4g of sodium dodecyl benzene sulfonate, dissolving, adding into a 250ml three-neck flask, adjusting the stirring speed, adding 45g of the emulsion of the microcapsule core material obtained in the step 2), stirring for 5 minutes, adding 45g of the urea-formaldehyde resin prepolymer in the step 1) and 0.5g of resorcinol (urea-formaldehyde resin curing accelerator), adding 2 drops of N-octanol, stirring at a constant speed for 5 minutes, adjusting the pH value of the system to 5-6 by using 0.4N dilute hydrochloric acid, heating to 60 ℃, reacting for 3 hours, filtering to remove the urea-formaldehyde resin prepolymer and the core material which do not participate in the reaction, cleaning the obtained product, drying at a low temperature, and finally collecting the dried capsules to obtain the microcapsule product (see figures 1 and 2).

As can be seen from the SEM and TEM topographic images of the microcapsules in FIG. 1, the SEM shows the spherical structure of the microcapsules, and the TEM shows the core-shell structure of the microcapsules. In the infrared diagram of the microcapsule in fig. 2, the microcapsule contains corrosion inhibitor groups, including hydroxyl, phosphate, and carbonyl groups.

EXAMPLE 2 preparation of toughened modified resin

1) Synthesis of a polyurethane prepolymer: 70g of elastomer polyether polyol (molecular weight of 800-2000) is dehydrated for 1h in vacuum at 120 ℃, then the temperature is reduced to 40 ℃ under the protection of nitrogen, 12g of hexamethylene diisocyanate is added, the temperature of the system is raised to 80 ℃ under the protection of nitrogen, and the prepolymer is obtained after reaction for 3 h.

2) Synthesis of polyurethane toughened epoxy resin: adding 80g of bisphenol A type E-51 epoxy resin into the prepolymer of the reaction, reacting for 1 hour at 80 ℃, adding a few drops of dibutyltin dilaurate, continuing to react for 0.5 hour, vacuumizing and defoaming until no bubble is formed, cooling to 40 ℃, and discharging (see figure 3).

And (3) carrying out tensile property measurement on the obtained toughened modified resin and the unmodified epoxy resin B, specifically measuring the change of the tensile strength and the displacement of the resin along with time. (see fig. 3);

as can be seen from the comparison of the tensile properties of the toughened modified resin and the unmodified pure epoxy resin in FIG. 3, the maximum tensile stress of the toughened modified resin is 2 times greater than that of the unmodified epoxy resin, the coating tensile displacement can be continuously increased under the maximum tensile stress, and for the unmodified epoxy resin, no displacement exists after the maximum tensile stress is reached, which indicates that the flexibility of the modified resin is obviously enhanced.

Example 31 preparation of epoxy microcapsule primer

(1) Weighing 2% of the prepared epoxy microcapsule, adding the epoxy microcapsule into methyl isobutyl ketone and xylene in a mass ratio of 1:1, uniformly dispersing the epoxy microcapsule by using a high-speed dispersion machine, adding part of organic resin A into the organic solvent containing the epoxy microcapsule, continuously and uniformly dispersing at high speed, adding 1.1% of defoaming agent BYK051 for the primer, 1.2% of dispersing agent BYK-P104S, 15% of zinc phosphate, 8% of aluminum powder, 8% of talcum powder, 5% of titanium pigment and 2% of white carbon black into the primer, uniformly dispersing the primer and obtaining a dispersion for later use.

(2) Mixing the dispersion obtained in the step (1) with the residual primer organic resin A, then adding 1% of a leveling agent BYK310, and fully and uniformly stirring to obtain an organic resin dispersion liquid;

(3) and (3) adding a curing agent matched with the primer resin into the organic resin dispersion liquid obtained in the step (2) according to the volume ratio of 1:2.5, fully and uniformly stirring, and drying to obtain the primer for the flexible self-repairing anticorrosion matched coating on the inner wall of the seawater steel pipeline.

The organic solvent is methyl isobutyl ketone and xylene, the mass ratio of the methyl isobutyl ketone to the xylene is 1:1, and polyamide 650 is used as a curing agent; the epoxy resin is bisphenol A type E-51.

EXAMPLE 41 preparation of toughened modified resin topcoat

(1) Weighing the toughening modified resin according to the weight ratio of the toughening modified resin to the organic resin B of 1:10, adding the toughening modified resin into the mixture of methyl isobutyl ketone and xylene in the mass ratio of 1:1, uniformly dispersing the toughening modified resin and the organic resin B by using a high-speed dispersion machine, adding part of the finishing coat organic resin B into the dispersion liquid containing the toughening modified resin, continuously stirring at a high speed, adding 1% of defoamer BYK051 for finishing coat, 1.1% of dispersant BYK-P104S, mica iron oxide 9%, calcium carbonate 10%, talcum powder 10% and titanium dioxide 13% into the dispersion liquid, uniformly dispersing the mixture to obtain a dispersion for later use;

(2) mixing the dispersion obtained in the step (1) with the residual finish paint organic resin B, then adding 0.6% of leveling agent BYK310 and 1.5% of thickening agent, and fully and uniformly stirring to obtain organic resin dispersion liquid;

(3) and (3) adding a curing agent matched with the finish paint in a volume ratio of 1:4 into the organic resin dispersion liquid obtained in the step (1), fully and uniformly stirring, and drying to obtain the finish paint of the flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline.

The curing agent is polyether amine T403, and the organic resin B is E-20 type epoxy resin.

Example 51 preparation of Flexible self-repairing anticorrosion matched coating for inner wall of seawater Steel pipeline

(1) Weighing 3.0g of epoxy microcapsule primer, uniformly coating the epoxy microcapsule primer on the surface of a treated steel test plate (150mm x 70mm), adjusting the temperature of an oven to 50 ℃, taking out after 2 hours, placing the steel test plate to room temperature (23 +/-2 ℃), and cooling the steel test plate for later use.

(2) And (3) weighing 2.8g of toughened modified resin finish paint, uniformly coating the toughened modified resin finish paint on the test plate to be used in the step (1), putting the test plate at room temperature (23 +/-2 ℃), and drying to obtain the flexible self-repairing anticorrosion matched coating on the inner wall of the seawater steel pipeline.

EXAMPLE 62 preparation of epoxy microcapsule primer

(1) Weighing 2% of the prepared epoxy microcapsule according to the weight percentage, adding the epoxy microcapsule into methyl isobutyl ketone and xylene with the mass ratio of 1:1, uniformly dispersing the epoxy microcapsule by a high-speed dispersion machine, adding part of organic resin A into the organic solvent containing the epoxy microcapsule, continuously and uniformly dispersing at high speed, adding 1.1% of defoaming agent BYK051 for the primer, 1.2% of dispersing agent BYK-P104S, 15% of zinc phosphate, 10% of iron oxide red, 6% of talcum powder, 5% of white carbon black and 2% of white carbon black into the organic solvent, uniformly dispersing the titanium dioxide, and obtaining a dispersion for later use.

(2) Mixing the dispersion obtained in the step (1) with the residual primer organic resin A, then adding 1% of a leveling agent BYK310, and fully and uniformly stirring to obtain an organic resin dispersion liquid;

(3) and (3) adding a curing agent matched with the primer resin into the organic resin dispersion liquid obtained in the step (2) according to the volume ratio of 1:2.5, fully and uniformly stirring, and drying to obtain the primer for the flexible self-repairing anticorrosion matched coating on the inner wall of the seawater steel pipeline.

The organic solvent is methyl isobutyl ketone and xylene in a mass ratio of 1: 1; the curing agent is polyamide 650; the organic resin A is E-51 type epoxy resin.

EXAMPLE 72 preparation of toughened modified resin topcoat

(1) Weighing the toughening modified resin according to the weight ratio of the toughening modified resin to the organic resin B of 1:10, adding the toughening modified resin into the mixture of methyl isobutyl ketone and xylene with the mass ratio of 1:1, uniformly dispersing the toughening modified resin and the organic resin B by using a high-speed dispersion machine, adding part of the finish paint organic resin B into the dispersion liquid containing the toughening modified resin, continuously stirring at a high speed, adding 1% of defoamer BYK051 for finish paint, 1.1% of dispersant BYK-P104S, 10% of mica iron oxide, 8% of heavy calcium, 6% of light calcium carbonate and 10% of titanium dioxide into the dispersion liquid, uniformly dispersing the mixture to obtain a dispersion body for later use;

(2) mixing the dispersion obtained in the step (1) with the residual finish paint organic resin B, then adding 0.6% of leveling agent BYK310 and 1.5% of thickening agent HL-150, and fully and uniformly stirring to obtain an organic resin dispersion liquid;

(3) and (3) adding a curing agent matched with the finish paint in a volume ratio of 1:4 into the organic resin dispersion liquid obtained in the step (1), fully and uniformly stirring, and drying to obtain the finish paint of the flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline.

The curing agent is polyether amine T403; the organic resin B is E-20 type epoxy resin.

Example 82 preparation of Flexible self-repairing anticorrosion matched coating for inner wall of seawater Steel pipeline

(1) Weighing 4.0g of epoxy microcapsule primer, uniformly coating the epoxy microcapsule primer on the surface of a treated steel test plate (150mm x 70mm), adjusting the temperature of an oven to 50 ℃, taking out after 2 hours, placing the steel test plate to room temperature (23 +/-2 ℃), and cooling the steel test plate for later use.

(2) And (3.5 g) weighing the toughened modified resin finish paint, uniformly coating the toughened modified resin finish paint on the test plate to be used in the step (1), putting the test plate at room temperature (23 +/-2 ℃), and drying to obtain the flexible self-repairing anticorrosion matched coating on the inner wall of the seawater steel pipeline.

Application example: compared with the anticorrosion effect of the flexible self-repairing anticorrosion matching coating for the inner wall of the seawater steel pipeline

(1) Salt spray resistance of the coating

The flexible self-repairing anticorrosion matching coating and the blank epoxy coating for the inner wall of the steel pipeline, which are obtained in the embodiment, are simultaneously placed in a salt spray box with the concentration of 5% for 8 months, the flexible self-repairing anticorrosion matching coating and the blank epoxy coating are taken out and dried at room temperature, and a picture is taken (see figures 4 and 5), so that the surface of the composite coating is smooth and clean and has no phenomena of rusty spots, bubbling and peeling as can be seen from figure 4, while the surface of the blank epoxy coating has a large amount of rusty spots as can be seen from figure 5, but the coating of the invention has no phenomena.

(2) Electrochemical impedance spectrum of flexible self-repairing anticorrosion matched coating for inner wall of steel pipeline after salt spray test

After 4 months of salt spray testing in a salt spray test chamber, a dot with a diameter of 1mm was artificially destroyed in the center of the test surface, and the electrochemical impedance spectrum of the coating/metal system was then tested. A P4000+ electrochemical workstation is adopted, a saturated calomel electrode with a robust gold capillary tube is used as a reference electrode, a platinum sheet electrode is used as a counter electrode, a coating/carbon steel electrode is used as a working electrode, after the coating/carbon steel electrode is soaked in a simulated seawater solution to stabilize an Open Circuit Potential (OCP), EIS test is carried out under the OCP by using a sine wave disturbance amplitude value of 20mV and a frequency range of 100kHz-0.01Hz, and the result is shown in figure 6. As can be seen from FIG. 5, after 4 months of salt spray test, the system impedance of the coating of the present invention was 2 times greater than that of a pure epoxy coating after artificial damage. It can be seen that the coating of the present invention has superior corrosion protection capability over pure epoxy coatings.

(3) Cathode stripping resistance of flexible self-repairing anticorrosion matched coating for inner wall of steel pipeline

After 50 days of salt water immersion test, the coated test panels of the present invention showed the results of cathodic disbondment test at 1.5v, as shown in FIG. 7. The results show that the surface of the coating does not generate bubbling, stripping and rusting phenomena, and the cathode stripping resistance of the composite coating is good.

(4) The mechanical property of the flexible self-repairing anticorrosion matching coating for the inner wall of the 1# steel pipeline and the bending test result of the coating under a shaft rod with phi 2mm are shown in figure 8, and the results show that the coating does not crack, and the coating has excellent bending resistance and flexibility.

In the state after the 1kg weight was dropped from the height of 50cm and impacted on the surface of the coating, as shown in FIG. 9, it was found that the coating was not broken, cracked and peeled, indicating that the coating of the present invention had excellent impact resistance.

The coating matched with the visible embodiment has no phenomena of foaming, long rust, peeling and the like after passing the salt spray test for 8 months; and from the bending resistance and impact resistance test results, the coating has excellent mechanical properties and can resist the impact of seawater, sea sand and the like on the inner wall of the pipeline.

Claims (10)

1. A flexible self-repairing anticorrosion matched coating for the inner wall of a seawater steel pipeline is characterized in that: the matched coating consists of a primer and a finish; wherein, the primer comprises, by weight, 0.5-2% of epoxy microcapsule, 35-45% of pigment filler A, 10-20% of organic solvent A, 1-4.5% of auxiliary agent A, 20-30% of curing agent A, and the balance of organic resin A; the finishing paint comprises, by weight, 0.5-2% of toughening modified resin, 78-45% of pigment filler B40, 10-15% of organic solvent B10, 1-4.5% of auxiliary agent B, 15-20% of curing agent B15, and the balance of organic resin B.

2. The flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline as claimed in claim 1, which is characterized in that: the organic resin A is epoxy resin with the molecular weight of about 380-400; the pigment filler A is one or more of zinc phosphate, aluminum powder, iron oxide red, talcum powder and white carbon black; the curing agent A is an amine curing agent.

3. The flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline as claimed in claim 1, which is characterized in that: the epoxy microcapsule is of a core-shell structure; wherein, the core is epoxy resin added with corrosion inhibitor, and the shell layer is urea-formaldehyde resin prepolymer; the corrosion inhibitor is one or more of carboxylic acids and/or carboxylic acid derivatives.

4. The flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline as claimed in claim 3, which is characterized in that: the carboxyl terminal of the carboxylic acid corrosion inhibitor is connected with a functional group; the functional group is one or more of carboxyl, phosphonic acid group and hydroxyl.

5. The flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline as claimed in claim 1, which is characterized in that: the toughening modified resin is epoxy resin toughened and modified by polyurethane, and the toughening modified resin accounts for 8-15 wt% of the organic resin B.

6. The flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline as claimed in claim 1, which is characterized in that: the organic resin B is epoxy resin with the molecular weight of about 900-; the pigment filler B is one or more of mica iron oxide, calcium carbonate, talcum powder and titanium dioxide; the curing agent B is an amine curing agent.

7. The flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline as claimed in claim 1, which is characterized in that: the auxiliary agent A is a leveling agent accounting for 0.5-1% of the mass of the primer, a defoaming agent accounting for 1-1.5% of the mass of the primer and a dispersing agent accounting for 1-2% of the mass of the primer;

the auxiliary agent B is a leveling agent accounting for 0.5-1% of the mass of the finish paint, a defoaming agent accounting for 1-1.5% of the mass of the primer paint, a dispersing agent accounting for 1-2% of the mass of the primer paint and a thickening agent accounting for 1-2% of the mass of the primer paint;

the organic solvent A and the organic solvent B are methyl isobutyl ketone and xylene in a mass ratio of 2:1-1: 2.

8. The preparation method of the flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline, which is disclosed by claim 1, is characterized by comprising the following steps of: the epoxy microcapsule primer coating is coated on the surface of metal by scraping, and then the surface coating of the toughening modified resin is coated on the surface of the primer coating by scraping to form a flexible modified surface coating; wherein the thickness of the primer coating is more than or equal to 250 mu m, and the thickness of the finish coating is more than or equal to 200 mu m.

9. The preparation method of the flexible self-repairing anticorrosion matched coating for the inner wall of the seawater steel pipeline, as recited in claim 8, is characterized in that:

preparing the primer coating:

adding the epoxy microcapsules into the organic solvent A according to the proportion, uniformly dispersing, sequentially adding part of the organic resin A, the pigment filler A, the dispersing agent and the defoaming agent into the dispersion liquid, uniformly stirring and dispersing to obtain a dispersion body for later use;

mixing the obtained dispersoid with the residual organic resin A, then adding the leveling agent, fully and uniformly stirring, then adding the curing agent A, and drying to obtain the primer coating;

the preparation of the finish coat comprises the following steps:

adding the toughening modified resin into the organic solvent B according to the proportion, uniformly dispersing, sequentially adding part of the organic resin B, the pigment and filler B, the dispersing agent and the defoaming agent into the dispersion liquid, uniformly stirring and dispersing to obtain a dispersion for later use;

and mixing the obtained dispersion with the rest of the organic resin B, then adding the thickening agent and the leveling agent, fully and uniformly stirring, then adding the curing agent B, and drying to obtain the finish coat.

10. The method of claim 9, wherein: the metal is a water pipeline or chemical equipment.

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