A method for preparing a hydrotalcite in-situ composite fiber reinforced anticorrosion coating

Abstract

The application provides a preparation method of a hydrotalcite in-situ composite fiber reinforced anti-chlorine anticorrosive coating, characterized in that the coating is composed of hydrotalcite in-situ composite fiber fillers and organic coating. The preparation of the coating comprises the following steps: preparing precursor fibers by using an electrospinning technology, taking the fibers as a substrate, growing hydrotalcite nanosheets on the surface of the fibers as organic-inorganic hybrid micro / nano containers, and intercalating corrosion inhibitor molecules into the hydrotalcite in-situ composite fibers by an ion exchange method, so as to prepare the hydrotalcite in-situ composite fiber anticorrosive fillers. The above method can realize the uniform dispersion of the hydrotalcite in the coating with the aid of nanofibers, and the physical barrier effect of the fibers is enhanced with the aid of the hydrotalcite. With the extension of service time, the corrosion medium is easy to diffuse to the interface between the coating and the metal to cause a local corrosion reaction, the hydrotalcite structure can realize the adsorption of chlorine ions in the corrosion medium by virtue of its anion exchange performance, the released corrosion inhibitor can form an anticorrosive film on the metal surface, effectively inhibits the metal corrosion process, and is beneficial to the long-acting anticorrosive ability of the composite coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthesis of marine anticorrosive coating, in particular to a preparation method of a hydrotalcite in-situ composite fiber reinforced anti-chlorine anticorrosive coating. BACKGROUND

[0002] Anticorrosive coating is a simple method of directly blocking the metal surface corrosion medium by forming a protective barrier. Organic coating is widely used in surface coating applications due to its good mechanical properties and low cost. In view of the problem that the coating is easily damaged and thus loses the protection ability, the externally aided self-healing coating is widely concerned due to its crack healing ability. When the coating is damaged, the micro / nano container releases the repairing agent to repair the coating defects, thereby prolonging the service life of the coating.

[0003] In recent years, the research and application of hydrotalcite (LDH) as a micro / nano container in the field of corrosion prevention have been increasingly concerned. Hydrotalcite is an ionic layered compound composed of a positively charged octahedral metal hydroxide outer layer and an exchangeable anion intercalated for charge balance. Due to its layered structure and excellent interlayer anion exchange performance, hydrotalcite as a coating filler can effectively delay the diffusion of corrosion medium chloride ions in the coating. The hydrotalcite structure intercalated with corrosion inhibitors can also exchange anions with chloride ions, thereby releasing corrosion inhibitors and hindering the diffusion of chloride ions. However, due to the weak interaction between hydrotalcite and the coating substrate, agglomeration easily occurs, which leads to the generation of coating defects and the increase of corrosion medium diffusion channels. Therefore, improving the dispersibility of hydrotalcite in the coating is still a difficult problem to be solved at present.

[0004] Electrospun nanofibers have the advantages of easy molding, controllable material and morphology, and good compatibility with organic coatings, and are widely used in composite materials. Therefore, in the present application, hydrotalcite is grown in-situ on the surface of the fiber, which can improve the dispersibility of hydrotalcite nanosheets in the coating. Through ion exchange method, the corrosion inhibitor molecules are intercalated, the loading and release performance of the hydrotalcite structure to the corrosion inhibitor, the blocking ability to chloride ions are realized, and the long-term corrosion resistance of the composite coating is enhanced. SUMMARY

[0005] The technical task of the present application is to provide a preparation method of a hydrotalcite in-situ composite fiber reinforced anti-chlorine anticorrosive coating in view of the deficiencies of the prior art.

[0006] The technical scheme adopted by the present application to solve its technical problems is:

[0007] 1. A preparation method of a hydrotalcite in-situ composite fiber reinforced anti-chlorine anticorrosive coating, characterized in that the coating is composed of a hydrotalcite in-situ composite fiber filler and an organic coating, and the specific implementation steps are as follows:

[0008] 1) The polymer and the solvent are mixed in a mass ratio of 0.1:1-1.5, and stirred at a temperature of 60-80°C and a rotation speed of 400-700 rpm for 12-24 hours;

[0009] 2) The spinning solution is injected into the device to perform electrostatic spinning, i.e. to obtain precursor fibers, specifically:

[0010] 2.1) The spinning translation distance is set to 60-140 mm, the injector capacity is 10 mL, the positive voltage is set to 15-22 KV, the negative voltage is 2.5-4 KV, the injection rate is 1 mm / min, the receiving speed is 100 rpm, the translation speed is 40 mm / min, and the receiving distance is 15 cm;

[0011] 2.2) After 8-12 hours of spinning, the precursor fibers can be obtained;

[0012] 3) The surface modifier and the buffer are mixed in a mass ratio of 1-5:100, and the precursor fibers are added to be fully soaked to perform surface treatment on the precursor fibers, specifically:

[0013] 3.1) 6 g of Tris is dissolved in 500 mL of deionized water, 1.1 mL of hydrochloric acid (HCl) is added dropwise under stirring, and then the solution is poured into a 1 L volumetric flask and diluted with deionized water to obtain a 0.1 mol / L Tris-HCl buffer with a pH of 8.5;

[0014] 3.2) The surface modifier is dissolved in the Tris-HCl buffer in a mass ratio of 1-5:100, stirred at room temperature for 2-5 hours, then the precursor fibers are added to be fully soaked, stirred at a rotation speed of 200-500 r / min at room temperature for 12-18 hours, the surface-treated fibers are washed with deionized water for 3 times, and finally dried in a vacuum drying oven at 60°C to perform surface treatment on the precursor fibers;

[0015] 4) Hydrotalcite is directly grown on the surface of the modified precursor fibers by a hydrothermal method, specifically:

[0016] 4.1) Cobalt nitrate, aluminum nitrate, and sodium nitrate are fully dissolved in 100 mL of deionized water in a molar ratio of 1:1:2-5, and an ammonia solution is added dropwise to control the pH value of the solution during the titration. The solution is stirred at a high speed of 800-1200 rpm during titration to obtain a mixed solution;

[0017] 4.2) adding fibers into the mixed solution, transferring into a high-pressure reaction kettle after ultrasonic treatment for 30-60 minutes, reacting at 100-150 DEG C for 4-12 hours, taking out the product after the reaction is completed, cleaning 3 times with deionized water and anhydrous ethanol, and drying at 60 DEG C in a vacuum drying box to obtain the hydrotalcite in-situ composite fiber;

[0018] 5) carrying out the in-situ composite fiber of hydrotalcite by the ion exchange method to insert the corrosion inhibitor molecules, specifically:

[0019] 5.1) preparing 250mL of 0.1mol / L sodium hydroxide solution, boiling the solution with deionized water and treating with nitrogen for 20-40 minutes;

[0020] 5.2) preparing the corrosion inhibitor and 0.1mol / L sodium hydroxide solution according to the mass ratio of 1-5:100, adding the in-situ composite fiber of hydrotalcite into the solution, continuously stirring at 60-80 DEG C water bath for 48-96 hours to obtain the corrosion inhibitor intercalated hydrotalcite in-situ composite fiber;

[0021] 6) mixing the obtained corrosion inhibitor intercalated hydrotalcite in-situ composite fiber filler and organic coating according to the volume ratio of 1:1-5, coating on the surface of the metal substrate, drying at room temperature for 120-192 hours to obtain a self-repairing coating.

[0022] Optionally, the polymer is one of polyvinylidene fluoride, polyacrylonitrile and polyethylene glycol.

[0023] Optionally, the solvent is any one or several of acetone, N,N dimethylformamide.

[0024] Optionally, the surface modifier is any one or several of polydopamine and polyetherimide.

[0025] Optionally, the corrosion inhibitor is any one of benzotriazole, gallic acid and 2-mercaptobenzothiazole.

[0026] Optionally, the organic coating is any one of epoxy resin, alkyd resin and fluorocarbon resin.

[0027] The preparation method of the hydrotalcite in-situ composite fiber reinforced anti-chlorine corrosion coating of the application has the following beneficial effects compared with the prior art:

[0028] 1. The application provides a preparation method of a hydrotalcite in-situ composite fiber reinforced anti-chlorine corrosion coating.

[0029] 2. Experiments show that the hydrotalcite in-situ composite fiber reinforced anti-chlorine corrosion coating synthesized in this invention can adsorb chloride ions in corrosive media by virtue of the anion exchange properties of hydrotalcite, and the released corrosion inhibitor forms a corrosion inhibition film on the metal surface, effectively inhibiting the metal corrosion process.

[0030] 3. The hydrotalcite in-situ composite fiber reinforced organic coating of the present invention provides a longer-lasting and stable protection capability for metal substrates. Attached Figure Description

[0031] Appendix Figure 1 This is a scanning electron microscope image of the PVDF-LDH@BTA composite fiber synthesized in Example 1 of this invention;

[0032] Appendix Figure 2 This is an XRD comparison image of the PVDF-LDH@BTA composite fiber synthesized in Embodiment 1 of the present invention and a standard card;

[0033] Appendix Figure 3 This is the PVDF-LDH prepared in Example 2 of the present invention. 4h Scanning electron microscope image of @BTA;

[0034] Appendix Figure 4 This is the PVDF-LDH synthesized in Embodiment 3 of the present invention. 9h Scanning electron microscope image of BTA fibers;

[0035] Appendix Figure 5 This is the PVDF-LDH synthesized in Embodiment 3 of the present invention. 9h XRD comparison chart of BTA composite fiber and hydrotalcite standard card;

[0036] Appendix Figure 6 This is a potential change graph of the PAN-LDH@GA / epoxy coating synthesized in Example 4 of the present invention after long-term immersion in 3.5wt.% NaCl solution;

[0037] Appendix Figure 7 This is the electrochemical Bode plot of the PAN-LDH@GA / epoxy coating synthesized in Example 4 of this invention in 3.5 wt.% NaCl solution. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The application provides a preparation method of a hydrotalcite in-situ composite fiber reinforced anti-chlorine anticorrosive coating, characterized in that the coating is composed of hydrotalcite in-situ composite fiber fillers and organic coating, and the specific implementation steps are as follows:

[0040] 1) The polymer and the solvent are mixed according to a mass ratio of 0.1:1-1.5, and stirred at a rotating speed of 400-700 rpm in a temperature range of 60-80℃ for 12-24 hours;

[0041] 2) The spinning solution is injected into a device to perform electrostatic spinning, so that precursor fibers are obtained, and specifically:

[0042] 2.1) The spinning translation distance is set to 60-140 mm, the syringe capacity is 10 mL, the positive voltage is set to 15-22 KV, the negative voltage is set to 2.5-4 KV, the injection rate is 1 mm / min, the receiving speed is 100 revolutions / min, the translation speed is 40 mm / min, and the receiving distance is 15 cm;

[0043] 2.2) After spinning for 8-12 hours, the precursor fibers can be obtained;

[0044] 3) The surface modifier and the buffer solution are mixed according to a mass ratio of 1-5:100, and the precursor fibers are fully immersed to realize surface treatment of the precursor fibers, and specifically:

[0045] 3.1) 6 g of Tris is dissolved in 500 mL of deionized water, 1.1 mL of hydrochloric acid (HCl) is added dropwise under stirring, then the solution is poured into a 1L volumetric flask and deionized water is added to constant volume to prepare a 0.1 mol / L Tris-HCl buffer solution with a pH of 8.5;

[0046] 3.2) The surface modifier is dissolved in the Tris-HCl buffer solution according to a mass ratio of 1-5:100, stirred at room temperature for 2-5 hours, then the precursor fibers are fully immersed, stirred at a rotating speed of 200-500 r / min at room temperature for 12-18 hours, the surface-treated fibers are washed with deionized water for 3 times, and finally dried in a vacuum drying oven at 60℃ to realize surface treatment of the precursor fibers;

[0047] 4) Hydrotalcite is directly grown on the surface of the modified precursor fibers through a hydrothermal method, and specifically:

[0048] 4.1) Cobalt nitrate, aluminum nitrate and sodium nitrate are fully dissolved in 100 mL of deionized water according to a molar ratio of 1:1:2-5, and an ammonia solution is added dropwise to control the pH value of the solution during the titration, and the solution is stirred at a rotating speed of 800-1200 rpm during the titration to obtain a mixed solution;

[0049] 4.2) adding fibers into the mixed solution, transferring to a high-pressure reaction kettle after ultrasonic treatment for 30-60 minutes, reacting at 100-150 DEG C for 4-12 hours, taking out the product after the reaction is completed, cleaning 3 times with deionized water and anhydrous ethanol, and drying at 60 DEG C in a vacuum drying box to obtain the hydrotalcite in-situ composite fiber;

[0050] 5) carrying out the intercalation of the corrosion inhibitor molecules into the hydrotalcite in-situ composite fiber by ion exchange, specifically:

[0051] 5.1) preparing 250 mL of 0.1 mol / L sodium hydroxide solution, boiling the prepared solution with deionized water and treating with nitrogen for 20-40 minutes;

[0052] 5.2) mixing the corrosion inhibitor with the 0.1 mol / L sodium hydroxide solution according to the mass ratio of 1-5:100, adding the hydrotalcite in-situ composite fiber into the solution, continuously stirring at 60-80 DEG C for 48-96 hours to obtain the corrosion inhibitor intercalated hydrotalcite in-situ composite fiber;

[0053] 6) mixing the obtained corrosion inhibitor intercalated hydrotalcite in-situ composite fiber filler with the organic coating according to the volume ratio of 1:1-5, coating on the surface of the metal substrate, drying at room temperature for 120-192 hours to obtain the self-repairing coating.

[0054] The polymer in step 1) is any one of polyvinylidene fluoride, polyacrylonitrile and polyethylene glycol.

[0055] The solvent in step 1) is any one or several of acetone, N,N dimethylformamide.

[0056] The surface modifier in step 3) is any one or several of polydopamine and polyetherimide.

[0057] The corrosion inhibitor in step 5) is any one of benzotriazole, gallic acid and 2-mercaptobenzothiazole.

[0058] The organic coating in step 6) is any one of epoxy resin, alkyd resin and fluorocarbon resin. Example one

[0059] The application provides a preparation method of a hydrotalcite in-situ composite fiber reinforced anti-chlorine corrosion coating.

[0060] The specific implementation steps are as follows:

[0061] 1) Polyvinylidene fluoride (PVDF) and N, N dimethylformamide (DMF) are mixed in a ratio of 0.1:1 by mass, and stirred at a temperature range of 60°C for 12 hours at a speed of 500 rpm;

[0062] 2) The spinning solution is injected into the device to perform electrospinning, i.e. to obtain precursor fibers, specifically:

[0063] 2.1) The spinning translation distance is set to 100 mm, the injector capacity is 10 mL, the positive voltage is set to 20 KV, the negative voltage is 3 KV, the injection rate is 1 mm / min, the receiving rate is 100 rpm, the translation speed is 40 mm / min, and the receiving distance is 15 cm;

[0064] 2.2) After 8 hours of spinning, the precursor fibers can be obtained;

[0065] 3) The surface modifier polydopamine is mixed with the buffer in a ratio of 1:100 by mass, and the precursor fibers are fully immersed to achieve surface treatment of the precursor fibers, specifically:

[0066] 3.1) 6 g of Tris is dissolved in 500 mL of deionized water, 1.1 mL of hydrochloric acid (HCl) is added dropwise under stirring, and then the solution is poured into a 1 L volumetric flask and diluted with deionized water to obtain a 0.1 mol / L Tris-HCl buffer with a pH of 8.5;

[0067] 3.2) The surface modifier polydopamine is dissolved in the Tris-HCl buffer in a ratio of 1:100 by mass, stirred at room temperature for 2 hours, then the precursor fibers are fully immersed, stirred at a speed of 300 r / min at room temperature for 12 hours, the surface treated fibers are washed with deionized water for 3 times, and finally dried in a vacuum drying oven at 60°C to achieve surface treatment of the precursor fibers;

[0068] 4) The modified precursor fibers are directly grown with hydrotalcite (LDH) by a hydrothermal method, specifically:

[0069] 4.1) Cobalt nitrate, aluminum nitrate, and sodium nitrate are fully dissolved in 100 mL of deionized water in a molar ratio of 1:1:2, and ammonia solution is added dropwise to control the pH value of the solution during the titration. The solution is stirred at a speed of 800 rpm during titration to obtain a mixed solution;

[0070] 4.2) adding fibers into the mixed solution, after ultrasonic treatment for 30 minutes, transferring into a high-pressure reaction kettle to react at 110℃ for 4 hours, after the reaction is completed, cooling to room temperature to take out the product, washing 3 times with deionized water and anhydrous ethanol, and drying in a vacuum drying oven at 60℃ to obtain the hydrotalcite in-situ composite fiber (PVDF-LDH);

[0071] 5) carrying out the intercalation of the corrosion inhibitor molecules into the hydrotalcite in-situ composite fiber by ion exchange method, specifically:

[0072] 5.1) preparing 250mL of 0.1mol / L sodium hydroxide solution, boiling the prepared solution with deionized water and treating with nitrogen for 20 minutes;

[0073] 5.2) preparing the corrosion inhibitor benzotriazole (BTA) into the 0.1mol / L sodium hydroxide solution according to the mass ratio of 1:100, adding the hydrotalcite in-situ composite fiber into the solution, continuously stirring at 60℃ water bath for 48 hours to obtain the corrosion inhibitor intercalated hydrotalcite in-situ composite fiber (PVDF-LDH@BTA);

[0074] 6) mixing the obtained corrosion inhibitor intercalated hydrotalcite in-situ composite fiber filler (PVDF-LDH@BTA) with the alkyd resin according to the volume ratio of 1:2, coating on the surface of the metal substrate, drying at room temperature for 120 hours to obtain the self-repairing coating.

[0075] The above-obtained PVDF-LDH@BTA composite fiber is characterized and tested:

[0076] The scanning electron microscope photos of the above PVDF-LDH@BTA composite fiber are as shown in Figure 1 The fiber surface grows hydrotalcite nanosheets in-situ, and the fiber morphology is uniform.

[0077] The XRD comparison chart of the above PVDF-LDH@BTA composite fiber and the hydrotalcite standard card is as shown in Figure 2 Through comparison with the standard card, it can be proved that the hydrotalcite nanosheets have been grown in-situ on the fiber. Example Two

[0078] Another preparation method of the hydrotalcite in-situ composite fiber reinforced anti-chlorine corrosion coating of the present application is provided, which is composed of a hydrotalcite in-situ composite fiber filler and an organic coating.

[0079] The specific implementation steps are as follows:

[0080] 1) mixing polyvinylidene fluoride (PVDF) and acetone with N,N dimethylformamide (DMF) according to the mass ratio of 0.1:1, and stirring at a speed of 600rmp for 16 hours in the temperature range of 70℃;

[0081] 2) inject the spinning solution into the device, electrospinning, to obtain precursor fibers, specifically:

[0082] 2.1) set the spinning translation distance to 120 mm, the injector capacity to 10 mL, the positive voltage to 22 KV, the negative voltage to 3.2 KV, the injection rate to 1 mm / min, the receiving rate to 100 rpm, the translation speed to 40 mm / min, and the receiving distance to 15 cm;

[0083] 2.2) after 8 hours of spinning, the precursor fibers can be obtained;

[0084] 3) mix the surface modifier and the buffer solution in a mass ratio of 2:100, add the precursor fibers to fully soak them, and perform surface treatment on the precursor fibers, specifically:

[0085] 3.1) dissolve 6 g of tris(hydroxymethyl)aminomethane (Tris) in 500 mL of deionized water, and while stirring, add 1.1 mL of hydrochloric acid (HCl) dropwise to the solution, then pour the solution into a 1 L volumetric flask and add deionized water to make up the volume to obtain a 0.1 mol / L Tris-HCl buffer solution with a pH of 8.5;

[0086] 3.2) dissolve the surface modifier (polydopamine and polyetherimide) in the Tris-HCl buffer solution in a mass ratio of 1:100, stir at room temperature for 3 hours, then add the precursor fibers to fully soak them, stir at a speed of 200 r / min at room temperature for 12 hours, take out the surface-treated fibers, wash them with deionized water 3 times, and finally place them in a vacuum drying oven at 60°C to dry, to perform surface treatment on the precursor fibers;

[0087] 4) directly grow hydrotalcite (LDH) on the surface of the modified precursor fibers by a hydrothermal method, specifically:

[0088] 4.1) dissolve cobalt nitrate, aluminum nitrate, and sodium nitrate in a molar ratio of 1:1:2 into 100 mL of deionized water, and during the process, add an ammonia solution dropwise to control the pH value of the solution, and stir the solution at a speed of 800 rpm during titration to obtain a mixed solution;

[0089] 4.2) add the fibers to the mixed solution, ultrasonically treat for 30 minutes, then transfer them to a high-pressure reaction kettle and react at 110°C for 4 hours, after the reaction is completed, cool to room temperature, take out the product, wash it with deionized water and anhydrous ethanol 3 times, and then dry it in a vacuum drying oven at 60°C to obtain the hydrotalcite in-situ composite fibers (PVDF-LDH 4h );

[0090] 5) Corrosion inhibitor molecular intercalation of hydrotalcite composite fibers in situ via ion exchange method, specifically:

[0091] 5.1) Prepare 250 mL of 0.1 mol / L sodium hydroxide solution. Boil the solution in deionized water and purge with nitrogen for 20-40 minutes.

[0092] 5.2) A corrosion inhibitor benzotriazole (BTA) and a 0.1 mol / L sodium hydroxide solution were mixed at a mass ratio of 1-5:100. In-situ layered double hydroxide composite fibers were added to the solution, and the mixture was continuously stirred and reacted in a water bath at 60-80℃ for 48-96 hours to obtain corrosion inhibitor-intercalated layered double hydroxide in-situ composite fibers (PVDF-LDH). 4h @BTA);

[0093] 6) The obtained corrosion inhibitor intercalated hydrotalcite in-situ composite fiber filler and alkyd resin are mixed in a volume ratio of 1:2, coated on the surface of the metal substrate, and dried at room temperature for 120 hours to obtain a self-healing coating.

[0094] The above-mentioned PVDF-LDH was obtained 4h Characterization tests were performed on BTA and the self-healing coating:

[0095] The above PVDF-LDH 4h @BTA scanning electron microscope image as follows Figure 3 As shown, a hexagonal sheet-like structure of hydrotalcite is grown on the surface of nanofibers. Example 3

[0096] Another method for preparing a hydrotalcite in-situ composite fiber reinforced chlorine-resistant and corrosion-resistant coating according to the present invention, wherein the coating is composed of hydrotalcite in-situ composite fiber filler and organic coating.

[0097] The specific implementation steps are as follows:

[0098] 1) A mixture of polyvinylidene fluoride (PVDF), acetone, and N,N-dimethylformamide (DMF) was prepared at a mass ratio of 0.1:1 and stirred at 600 rpm for 16 hours within a temperature range of 70°C.

[0099] 2) The spinning solution is injected into the device for electrospinning to obtain the precursor fiber. Specifically:

[0100] 2.1) Set the spinning translation distance to 120mm, the syringe capacity to 10mL, the positive voltage to 22KV, the negative voltage to 3.2KV, the injection rate to 1mm / min, the receiving rate to 100 rpm, the translation speed to 40mm / min, and the receiving distance to 15cm.

[0101] 2.2) After 8 hours of spinning, precursor fibers can be obtained;

[0102] 3) The surface modifier and the buffer are mixed in a mass ratio of 2:100, and the precursor fibers are added to fully soak them, so as to realize surface treatment of the precursor fibers, specifically:

[0103] 3.1) 6g of Tris is dissolved in 500mL of deionized water, and 1.1mL of hydrochloric acid (HCl) is added dropwise under stirring, and then the solution is poured into a 1L volumetric flask and diluted with deionized water to obtain a 0.1mol / L Tris-HCl buffer with pH=8.5;

[0104] 3.2) The surface modifier (polydopamine and polyetherimide) is dissolved in the Tris-HCl buffer in a mass ratio of 1:100, stirred at room temperature for 3 hours, then the precursor fibers are added to fully soak them, and stirred at a speed of 200r / min at room temperature for 12 hours, the surface-treated fibers are washed with deionized water for 3 times, and finally dried in a vacuum drying oven at 60°C, so as to realize surface treatment of the precursor fibers;

[0105] 4) The LDH is directly grown on the surface of the modified precursor fibers by hydrothermal method, specifically:

[0106] 4.1) Cobalt nitrate, aluminum nitrate and sodium nitrate are fully dissolved in 100mL of deionized water in a molar ratio of 1:1:2, and ammonia solution is added dropwise to control the pH value of the solution during the titration, and the solution is stirred at a speed of 800rpm during the titration to obtain a mixed solution;

[0107] 4.2) The fibers are added to the mixed solution, ultrasonic treatment is performed for 30 minutes, and then the solution is transferred to a high-pressure reaction kettle and reacted at 110°C for 9 hours, after the reaction is completed, the product is taken out after cooling to room temperature, washed with deionized water and anhydrous ethanol for 3 times, and dried in a vacuum drying oven at 60°C, to obtain the LDH in-situ composite fiber (PVDF-LDH 9h );

[0108] 5) The LDH in-situ composite fiber is subjected to ion exchange for the insertion of corrosion inhibitor molecules, specifically:

[0109] 5.1) 250mL of 0.1mol / L sodium hydroxide solution is prepared, and the solution is boiled with deionized water and treated with nitrogen gas for 20-40 minutes;

[0110] 5.2) A corrosion inhibitor benzotriazole (BTA) and a 0.1 mol / L sodium hydroxide solution were mixed at a mass ratio of 1-5:100. In-situ layered double hydroxide composite fibers were added to the solution, and the mixture was continuously stirred and reacted in a water bath at 60-80℃ for 48-96 hours to obtain corrosion inhibitor-intercalated layered double hydroxide in-situ composite fibers (PVDF-LDH). 9h @BTA);

[0111] 6) The obtained corrosion inhibitor intercalated hydrotalcite in-situ composite fiber filler and alkyd resin are mixed in a volume ratio of 1:2, coated on the surface of the metal substrate, and dried at room temperature for 120 hours to obtain a self-healing coating.

[0112] The above-mentioned PVDF-LDH was obtained 9h Characterization tests were performed on BTA and the self-healing coating:

[0113] The above PVDF-LDH 9h @BTA scanning electron microscope image as follows Figure 4 As shown, hydrotalcite nanosheets are uniformly grown on the surface of nanofibers.

[0114] The above PVDF-LDH 9h XRD comparison chart of BTA composite fiber and hydrotalcite standard card as shown below Figure 5 As shown, PVDF-LDH exhibits typical LDH-like diffraction peaks. The reaction time is 9 hours. 9h The sharp (003) diffraction peak of @BTA indicates that the product has good crystallinity. Example 4

[0115] The present invention also provides a method for preparing a hydrotalcite in-situ composite fiber reinforced chlorine-resistant and corrosion-resistant coating, the coating being composed of hydrotalcite in-situ composite fiber filler and organic coating.

[0116] The specific implementation steps are as follows:

[0117] 1) Polyacrylonitrile (PAN) and N,N-dimethylformamide (DMF) were mixed in a mass ratio of 0.1:1 and stirred at 500 rpm for 12 hours within a temperature range of 60°C.

[0118] 2) The spinning solution is injected into the device for electrospinning to obtain the precursor fiber. Specifically:

[0119] 2.1) Set the spinning translation distance to 100mm, the syringe capacity to 10mL, the positive voltage to 20KV, the negative voltage to 3KV, the injection rate to 1mm / min, the receiving rate to 100 rpm, the translation speed to 40mm / min, and the receiving distance to 15cm.

[0120] 2.2) After 8 hours of spinning, precursor fibers can be obtained;

[0121] 3) The surface modifier polydopamine is mixed with the buffer in a mass ratio of 1:100, and the precursor fibers are fully immersed to realize surface treatment of the precursor fibers, specifically:

[0122] 3.1) 6g of Tris is dissolved in 500mL of deionized water, 1.1mL of hydrochloric acid (HCl) is added dropwise under stirring, then the solution is poured into a 1L volumetric flask and deionized water is added to constant volume to obtain a 0.1mol / L Tris-HCl buffer with pH=8.5;

[0123] 3.2) The surface modifier polydopamine is dissolved in the Tris-HCl buffer in a mass ratio of 1:100, stirred at room temperature for 2 hours, then the precursor fibers are fully immersed, stirred at a speed of 300r / min for 12 hours at room temperature, the surface treated fibers are washed with deionized water for 3 times, and finally dried in a vacuum drying oven at 60°C to realize surface treatment of the precursor fibers;

[0124] 4) Directly grow hydrotalcite (LDH) on the surface of the modified precursor fibers by hydrothermal method, specifically:

[0125] 4.1) Cobalt nitrate, aluminum nitrate, and sodium nitrate are fully dissolved in 100mL of deionized water in a molar ratio of 1:1:2, and ammonia solution is added dropwise to control the pH value of the solution during the titration. The solution is stirred at a speed of 800rpm during titration to obtain a mixed solution;

[0126] 4.2) The fibers are added to the mixed solution, ultrasonically treated for 30 minutes, then transferred to a high-pressure reaction kettle and reacted at 110°C for 4 hours. After the reaction is completed, the product is taken out after cooling to room temperature, washed with deionized water and anhydrous ethanol for 3 times, and dried in a vacuum drying oven at 60°C to obtain hydrotalcite in-situ composite fibers (PAN-LDH);

[0127] 5) The hydrotalcite in-situ composite fibers are intercalated with corrosion inhibitor molecules by ion exchange method, specifically:

[0128] 5.1) 250mL of 0.1mol / L sodium hydroxide solution is prepared, and the solution is boiled with deionized water and treated with nitrogen gas for 20 minutes;

[0129] 5.2) The corrosion inhibitor gallic acid (GA) is mixed with 0.1mol / L sodium hydroxide solution in a mass ratio of 1:100, and the hydrotalcite in-situ composite fibers are added to the solution, and continuously stirred at 60°C water bath for 48 hours to obtain corrosion inhibitor intercalated hydrotalcite in-situ composite fibers (PAN-LDH@GA);

[0130] 6) The obtained corrosion inhibitor intercalated layered double hydroxide in-situ composite fiber filler (PAN-LDH@GA) was mixed with epoxy resin in a volume ratio of 1:2, coated on the surface of the metal substrate, dried at room temperature for 120 hours, and a self-repairing coating (PAN-LDH@GA / epoxy) was obtained.

[0131] The PAN-LDH@GA / epoxy coating obtained above was characterized and tested:

[0132] The potential change of the PAN-LDH@GA / epoxy coating during long-term immersion in 3.5wt.% NaCl solution is shown in Figure 6 The open circuit potential change trend of the composite coating is divided into two stages: the first stage is the initial stage of immersion, i.e. the first 3 days, and the open circuit potential decreases sharply; the second stage is that the open circuit potential tends to be stable and is at a relatively high value, indicating that the coating has good long-term protection performance.

[0133] The Bode plot of the PAN-LDH@GA / epoxy coating during long-term immersion in 3.5wt.% NaCl solution is shown in Figure 7 The impedance modulus |Z| of the PAN-LDH@GA / epoxy coating 0.01Hz always remains in the same order of magnitude (10 8 Ω·cm 2 ) and shows an overall upward trend.

[0134] Although preferred embodiments of the application have been described, those skilled in the art will be able to make additional changes and modifications to these embodiments once they have the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all the preferred embodiments and all changes and modifications falling within the scope of the application.

[0135] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

[0136] In addition to the technical features described in the specification, all are known to those skilled in the art.

Claims

1. A method for preparing a hydrotalcite-reinforced composite fiber-reinforced chlorine-resistant and corrosion-resistant coating, characterized in that, The coating consists of in-situ composite fiber filler made of hydrotalcite and organic coating. The specific implementation steps are as follows: 1) The polymer and solvent are mixed in a mass ratio of 0.1:1-1.5 and stirred at a speed of 400-700 rpm for 12-24 hours within a temperature range of 60-80℃. 2) The spinning solution is injected into the device for electrospinning to obtain the precursor fiber. Specifically: 2.1) Set the spinning translation distance to 60-140mm, the syringe capacity to 10mL, the positive voltage to 15-22KV, the negative voltage to 2.5-4KV, the injection rate to 1mm / min, the receiving rate to 100 rpm, the translation speed to 40mm / min, and the receiving distance to 15cm. 2.2) After spinning for 8-12 hours, precursor fibers can be obtained; 3) Mix the surface modifier and buffer solution at a mass ratio of 1-5:100, add the precursor fiber and allow it to fully impregnate, thereby achieving surface treatment of the precursor fiber. Specifically: 3.1) Dissolve 6g of tris(hydroxymethyl)aminomethane in 500mL of deionized water, add 1.1mL of hydrochloric acid dropwise while stirring, then pour the solution into a 1L volumetric flask and add deionized water to make up to volume to prepare a 0.1mol / L Tris-HCl buffer solution with pH=8.

5. 3.2) Dissolve the surface modifier in Tris-HCl buffer at a mass ratio of 1-5:100 and stir at room temperature for 2-5 hours. Then add the precursor fiber and allow it to fully impregnate. Stir at room temperature for 12-18 hours at a speed of 200-500 r / min. Remove the surface-treated fiber and wash it three times with deionized water. Finally, place it in a vacuum drying oven at 60℃ to dry it, thus achieving surface treatment of the precursor fiber. 4) Hydrotalcite is directly grown on the surface of the modified precursor fibers using a hydrothermal method, specifically: 4.1) Mix cobalt nitrate, aluminum nitrate, and sodium nitrate thoroughly in 100 mL of deionized water at a molar ratio of 1:1:2-5. During the titration, add ammonia solution dropwise to control the pH value of the solution. Stir the solution vigorously at 800-1200 rpm during the titration to obtain a mixed solution. 4.2) Add fibers to the mixed solution, sonicate for 30-60 minutes, then transfer to a high-pressure reactor and react at 100-150℃ for 4-12 hours. After the reaction is completed, cool to room temperature and take out the product. Wash with deionized water and anhydrous ethanol three times and then dry in a vacuum drying oven at 60℃ to obtain in-situ hydrotalcite composite fibers. 5) Corrosion inhibitor molecular intercalation of hydrotalcite composite fibers in situ via ion exchange method, specifically: 5.1) Prepare 250 mL of 0.1 mol / L sodium hydroxide solution. Boil the solution in deionized water and purge with nitrogen for 20-40 minutes. 5.2) The corrosion inhibitor and 0.1 mol / L sodium hydroxide solution are mixed in a mass ratio of 1-5:

100. The in-situ composite fiber of hydrotalcite is added to the solution and the mixture is stirred continuously in a water bath at 60-80℃ for 48-96 hours to obtain the corrosion inhibitor intercalated hydrotalcite in-situ composite fiber. 6) The obtained corrosion inhibitor intercalated hydrotalcite in-situ composite fiber filler and organic coating are mixed in a volume ratio of 1:1-5, coated on the surface of the metal substrate, and dried at room temperature for 120-192 hours to obtain a hydrotalcite in-situ composite fiber reinforced chlorine-resistant and anti-corrosion coating. The polymer is any one of polyvinylidene fluoride, polyacrylonitrile, and polyethylene glycol; the solvent is any one or more of acetone and N,N-dimethylformamide; the surface modifier is any one or more of polydopamine and polyetherimide; and the corrosion inhibitor is any one of benzotriazole, gallic acid, and 2-mercaptobenzothiazole.

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