A dual-load hydroxyapatite / ZIF composite anticorrosive filler, a preparation method and application thereof

Abstract

The application discloses a double-load hydroxyapatite / ZIF composite anticorrosive filler which is prepared from tannic acid modified hydroxyapatite nanosheet, 2-methyl imidazole, zinc nitrate hexahydrate, 2-amino benzothiazole and methanol. The application has both active protection and passive protection, blocks corrosion medium through the shielding effect of two-dimensional material, and the loaded tannic acid and 2-amino benzothiazole can release to generate passivation film by coordinating iron ions, effectively prevents further corrosion, and prolongs the service life of the organic coating.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of anticorrosive coating, and particularly relates to a double-loaded hydroxyapatite / ZIF composite anticorrosive filler, a preparation method thereof and application thereof. BACKGROUND

[0002] Traditional organic anticorrosive coatings mainly rely on the shielding effect on corrosive media to protect the metal substrate, but once the coating is damaged, the protection effect is lost, so the anticorrosive life is limited. Intelligent coatings can actively respond to corrosion, release corrosion inhibitor coordinated iron ions to form a passivation film, and produce a self-healing effect to prevent further corrosion, effectively improving the service life of organic coatings.

[0003] The compatibility of inorganic fillers with polymer matrix resins has always been an important factor restricting the modification of blending. Hydroxyapatite (HAp) is a common inorganic material widely used in various fields. When it is applied to polymer modification, the surface of the material needs to be modified to improve the compatibility with the resin matrix. Researchers have made many exploratory works on the modification of hydroxyapatite by dopamine in situ coating in the field of anticorrosive coatings. When the polymer containing coordination functional groups is used to modify hydroxyapatite nanosheets, it can be used as a layered nanocapsule. Tannic acid is a plant extract molecule containing abundant catechol functional groups and pyrogallol functional groups. It is natural, non-toxic and biodegradable. Due to the strong coordination ability of catechol functional groups, it is used as a corrosion inhibitor. The inhibiting effect of tannic acid in an acidic solution is achieved by forming multiple layers of iron tannate through the chemical adsorption of tannic acid molecules on the metal surface to block the corrosive medium. ZIF is also a commonly used anticorrosive nanocapsule. However, the combination of tannic acid modified hydroxyapatite and ZIF for the preparation of anticorrosive organic resin coating compositions has not been reported in the prior art.

[0004] By modifying the hydroxyapatite nanosheet with tannic acid, the compatibility of the hydroxyapatite nanosheet with the polymer matrix is improved, and the hydroxyapatite nanosheet plays a role as a layered nanocapsule. In combination with the ZIF nanocapsule loaded with nitrogen heterocyclic corrosion inhibitors, the double-loading strategy combines active protection and passive protection to construct an intelligent coating, which has broad application prospects. SUMMARY

[0005] The present application aims to overcome the defects of the prior art and provides a double-loaded hydroxyapatite / ZIF composite anticorrosive filler.

[0006] Another object of the present application is to provide a preparation method of the double-loaded hydroxyapatite / ZIF composite anticorrosive filler.

[0007] Still another object of the present application is to provide the application of the double-loaded hydroxyapatite / ZIF composite anticorrosive filler.

[0008] The technical scheme of the present application is as follows: a double-loaded hydroxyapatite / ZIF composite anticorrosive filler is prepared from tannic acid modified hydroxyapatite nanosheets, 2-methyl imidazole, zinc nitrate hexahydrate, 2-amino benzothiazole and methanol;

[0009] The tannic acid modified hydroxyapatite nanosheets are prepared from hydroxyapatite nanosheets, tannic acid, a tris-hydroxymethyl aminomethane solution and deionized water.

[0010] The hydroxyapatite nanosheets are prepared from calcium nitrate tetrahydrate, ammonium dihydrogen phosphate, urea and deionized water.

[0011] In a preferred embodiment of the present application, the tannic acid modified hydroxyapatite is prepared from hydroxyapatite nanosheets, tannic acid, a tris-hydroxymethyl aminomethane solution and deionized water in a mass ratio of 10-15:10-15:15-20:100-150.

[0012] Further preferably, the hydroxyapatite nanosheets are prepared from calcium nitrate tetrahydrate, ammonium dihydrogen phosphate, urea and deionized water in a mass ratio of 25-30:5-10:20-25:100-150.

[0013] In a preferred embodiment of the present application, it is prepared from tannic acid modified hydroxyapatite nanosheets, 2-methyl imidazole, zinc nitrate hexahydrate, 2-amino benzothiazole and methanol in a mass ratio of 10-15:20-30:10-15:10-15:100-150.

[0014] The preparation method of the double-loaded hydroxyapatite / ZIF composite anticorrosive filler comprises the following steps:

[0015] (1) Dissolve and mix calcium nitrate tetrahydrate, ammonium dihydrogen phosphate, urea and deionized water, then perform hydrothermal reaction at 110-120℃ for 2-4h, and then perform centrifugal washing to obtain the hydroxyapatite nanosheets;

[0016] (2) Ultrasonically disperse the above hydroxyapatite nanosheets in deionized water, then add tannic acid and mix uniformly, then adjust the pH to weak alkalinity with a tris-hydroxymethyl aminomethane solution, stir at room temperature for 4-6h, and then perform centrifugal washing and freeze drying to obtain the tannic acid modified hydroxyapatite nanosheets;

[0017] (3) Ultrasonically disperse the above tannic acid modified hydroxyapatite nanosheets in methanol, then add methanol solutions of zinc nitrate hexahydrate, 2-amino benzothiazole and 2-methyl imidazole, and then perform sufficient reaction at room temperature after stirring, and then perform centrifugal and drying to obtain the double-loaded hydroxyapatite / ZIF composite anticorrosive filler

[0018] Use of the above-mentioned dual-loaded hydroxyapatite / ZIF composite anticorrosive filler in the preparation of an anticorrosive organic resin coating composition.

[0019] In a preferred embodiment of the present application, the raw materials of the anticorrosive organic resin coating composition include an organic resin base material.

[0020] Further preferably, the organic resin base material is selected from epoxy resin, polyurethane and polyester resin.

[0021] An anticorrosive organic resin coating composition, the raw materials of which include an organic resin base material and the above-mentioned dual-loaded hydroxyapatite / ZIF composite anticorrosive filler.

[0022] In a preferred embodiment of the present application, the organic resin base material is selected from epoxy resin, polyurethane and polyester resin.

[0023] The beneficial effects of the present application are:

[0024] 1. In the dual-loaded hydroxyapatite / ZIF composite anticorrosive filler of the present application, the tannic acid modification improves the dispersibility of hydroxyapatite and realizes the loading of layered nanocapsules, and 2-aminobenzothiazole is loaded through the ZIF nanocapsules.

[0025] 2. The dual-loaded hydroxyapatite / ZIF composite anticorrosive filler of the present application has both active and passive protection effects, blocks the corrosion medium through the shielding effect of two-dimensional materials, and releases tannic acid and 2-aminobenzothiazole to coordinate iron ions to form a passivation film, effectively preventing further corrosion and prolonging the service life of the organic coating.

[0026] 3. The composite coating prepared from the anticorrosive organic resin coating composition of the present application has improved hydrophobicity and mechanical properties, and also has good corrosion resistance, wherein the low-frequency impedance value of the modified coating is two orders of magnitude higher than that of the unmodified pure polymer coating after 28 days of salt water immersion, and the 14-day cross-hatch salt spray corrosion test also shows lighter corrosion and better salt spray resistance. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 XRD and infrared spectra of the hydroxyapatite nanosheets, tannic acid-modified hydroxyapatite nanosheets and dual-loaded hydroxyapatite / ZIF composite anticorrosive filler obtained in Example 1 of the present application.

[0028] Figure 2 Nitrogen adsorption graph of the hydroxyapatite nanosheets, tannic acid-modified hydroxyapatite nanosheets and dual-loaded hydroxyapatite / ZIF composite anticorrosive filler obtained in Example 1 of the present application.

[0029] Figure 3Morphology scanning electron microscope and transmission electron microscope images of the double-loaded hydroxyapatite / ZIF composite anticorrosive filler obtained in Example 1 of the present application

[0030] Figure 4 Response inhibitor release curve of the double-loaded hydroxyapatite / ZIF composite anticorrosive filler obtained in Example 1 of the present application.

[0031] Figure 5 Water contact angle test drawing of the coating sample obtained in Example 2 of the present application.

[0032] Figure 6 Optical photo of the cross-hatch salt spray test of the coating sample obtained in Example 2 of the present application.

[0033] Figure 7 Salt water immersion electrochemical impedance spectrogram of the coating sample obtained in Example 2 of the present application. DETAILED DESCRIPTION

[0034] The technical solutions of the present application are further described and explained below by specific embodiments in conjunction with the accompanying drawings.

[0035] Example 1 Preparation of hydroxyapatite nanosheets, tannic acid modified hydroxyapatite nanosheets, and double-loaded hydroxyapatite / ZIF composite anticorrosive filler

[0036] (1) 2.95 g of Ca(NO3)2·4H2O and 0.86 g of NH4H2PO4 were dissolved in 100 mL of deionized water, stirred at room temperature for 30 min, and then 2.25 g of urea was added as a coprecipitation reagent while stirring. The above solution was transferred into a hydrothermal polytetrafluoroethylene liner, heated to 120℃ at a heating rate of 10℃ / min, and maintained for 3 h. Finally, the hydrothermal kettle was cooled to room temperature. After the hydrothermal reaction was completed, the product was centrifuged at a speed of 11000 r / min, washed with deionized water and anhydrous ethanol for 3 times. The washed product was dried in a vacuum oven at 60℃ for 12 h to obtain a white solid powder product, which was hydroxyapatite nanosheets (HAp).

[0037] (2) 0.1 g of HAp nanosheets was added to 20 mL of deionized water and ultrasonically dispersed for 30 min, and then 0.1 g of tannic acid was added and stirred with a magnetic stirrer until completely dissolved. The pH value of the solution was adjusted to 8.0 with 1M tris-hydroxymethyl aminomethane (Tris) solution and continuously stirred for 5 h. The mixed solution gradually turned green, obtaining a suspension of tannic acid coated HAp nanosheets. Finally, it was centrifuged at a speed of 11000 r / min for 5 min and washed several times with deionized water, and finally freeze-dried in a freeze dryer for 12 h to obtain a green solid powder of tannic acid modified hydroxyapatite nanosheets (HAp@TA).

[0038] (3) 0.5 g HAp@TA powder was weighed into a 150 mL single-necked flask, 50 mL of methanol was added and ultrasonic dispersion was performed for 30 min, 0.5 g of zinc nitrate hexahydrate was weighed and dissolved in 12.5 mL of methanol, the zinc nitrate hexahydrate solution was added to the flask, after stirring at room temperature for 30 min, 0.5 g of 2-ABT was weighed and dissolved in 12.5 mL of methanol in a beaker, the solution was added dropwise to the flask and stirring was continued for 30 min. Finally, 1.1 g of 2-methylimidazole was weighed and dissolved in 12.5 mL of methanol in a beaker, the 2-methylimidazole solution was added to the flask and stirring was continued at room temperature for 24 h. The reaction mixture was centrifuged at 8000 r / min in a centrifuge for 5 min, and then the centrifuged product was washed with methanol several times. After the centrifuged and washed product was placed in a vacuum oven at 60°C for 12 h, a light green solid powder of double-loaded hydroxyapatite / ZIF composite corrosion inhibitor (ABT@ZIF8-HAp@TA) was finally obtained. Modification was made to step (3) by not adding 2-ABT, and the rest was the same, and ZIF8-HAp@TA was obtained for comparison.

[0039] In this embodiment, the XRD spectra and infrared spectra of the obtained HAp, HAp@TA, ZIF8-HAp@TA and ABT@ZIF8-HAp@TA are shown in Figure 1 The nitrogen adsorption effect is shown in Figure 2 .

[0040] The morphology scanning electron microscope images and transmission electron microscope images of the ABT@ZIF8-HAp@TA obtained in the embodiment of the application are shown in Figure 3 The responsive corrosion inhibitor release curve is shown in Figure 4 .

[0041] It can be seen from the XRD and infrared spectra that the ABT@ZIF8-HAp@TA has a crystal structure and corresponding functional groups, the nitrogen adsorption results show that the material has a porous framework structure, the transmission electron microscope and scanning electron microscope show that the ZIF particles loaded with corrosion inhibitors are successfully grown on the surface of hydroxyapatite, and the ultraviolet test shows that the ABT@ZIF8-HAp@TA material can release corrosion inhibitors to complex metal ions under acidic and neutral conditions, which can prove that the ABT@ZIF8-HAp@TA material is successfully synthesized.

[0042] Example 2

[0043] Take 35 g of epoxy resin 901 solid powder into a 100 mL paint tank, add 21 g of mixed solvent of xylene and n-butanol (mass ratio of xylene to n-butanol is 4:1), place the paint tank in the paint disperser and shake for 12 h to obtain an epoxy resin 901 solution with a solid content of 62.5%. Take 0.175 g of ABT@ZIF8-HAp@TA prepared in Example 1 (0.5 wt% of the epoxy resin solid content), disperse it in 14 g of mixed solvent of xylene and n-butanol, and ultrasonically disperse in an ultrasonic cleaner for 2 h, then add the epoxy resin 901 solution, and use a high-speed mixer to stir and disperse at a speed of 2000 r / min for 30 min. Add 0.24 g of leveling agent, defoaming agent, dispersant and anti-settling agent respectively, and continue to stir for 30 min to obtain paint component A. Then add 11.6 g (1 / 3 of the mass fraction of the epoxy resin) of polyamide 8200 curing agent, and continue to stir for 15 min to obtain the anti-corrosion functional coating. Use a wire bar coater to coat the coating on a steel plate to prepare a coating sample, and test the mechanical properties, hydrophobic properties and corrosion resistance of the coating after curing.

[0044] To explore the mechanical properties of the modified composite epoxy system, the adhesion, flexibility, impact resistance, hardness and bending resistance of the composite waterborne epoxy coating were tested, and the specific results are shown in Table 1.

[0045] Table 1 Mechanical properties of epoxy composite anti-corrosion coating

[0046]

[0047] The coating sample was subjected to salt spray test according to GB6458-86. The salt spray test was carried out using a Q-Lab salt spray test chamber. The concentration of the sodium chloride solution used in the test was 5%, and the test pressure was determined by the salt spray deposition test. Before testing, the back and edges of the coating sample were sealed to prevent corrosion current generated by edge corrosion and back corrosion under salt spray corrosion from affecting the corrosion of the scratch area during testing. The edges and back of the coating sample were sealed with transparent tape, and the tape joints on the surface of the sample were further sealed with room temperature curing silicone. After the silicone was completely cured, the surface of the sample was cross-cut using a craft knife until it contacted the surface of the steel plate. The cross-cut coating sample was placed in the sample slot of the salt spray test chamber with a vertical angle of 5°. The salt spray resistance of the sample was evaluated by observing the corrosion of the coating sample at different times, and the salt spray corrosion was completed in 14 days. The specific results are shown in Table 2. Figures 5 to 7As shown, the AZHT / EP sample added with ABT@ZIF8-HAp@TA showed the largest water contact angle, that is, the best hydrophobic performance, and also showed the highest low-frequency impedance value after 28-day salt water immersion, that is, the best corrosion resistance, and also showed the lightest corrosion degree in the 14-day cross-hatch salt spray test, so the comprehensive corrosion resistance of AZHT / EP is the best, indicating that ABT@ZIF8-HAp@TA greatly improves the corrosion resistance of the epoxy coating.

[0048] The above description is only the preferred embodiment of the present application, and therefore cannot limit the scope of the present application, that is, equivalent changes and modifications made according to the scope of the present patent and the content of the specification should still be within the scope of the present application.

Claims

1. A dual-loaded hydroxyapatite / ZIF composite anticorrosive filler, characterized in that: It is prepared from tannic acid modified hydroxyapatite nanosheet, 2-methyl imidazole, zinc nitrate hexahydrate, 2-amino benzothiazole and methanol; The tannic acid modified hydroxyapatite nanosheet is prepared from hydroxyapatite nanosheet, tannic acid, tris-hydroxymethyl aminomethane solution and deionized water. The hydroxyapatite nanosheet is prepared from calcium nitrate tetrahydrate, ammonium dihydrogen phosphate, urea and deionized water.

2. The dual-loaded hydroxyapatite / ZIF composite anticorrosive filler of claim 1, wherein: The tannic acid modified hydroxyapatite nanosheet is prepared from hydroxyapatite nanosheet, tannic acid, tris-hydroxymethyl aminomethane solution and deionized water in a mass ratio of 10-15:10-15:15-20:100-150.

3. The dual-loaded hydroxyapatite / ZIF composite anticorrosive filler of claim 2, wherein: The hydroxyapatite nanosheet is prepared from calcium nitrate tetrahydrate, ammonium dihydrogen phosphate, urea and deionized water in a mass ratio of 25-30:5-10:20-25:100-150.

4. A dual-loaded hydroxyapatite / ZIF composite anticorrosive filler according to any one of claims 1 to 3, characterized in that: It is prepared from tannic acid modified hydroxyapatite nanosheet, 2-methyl imidazole, zinc nitrate hexahydrate, 2-amino benzothiazole and methanol in a mass ratio of 10-15:20-30:10-15:10-15:100-150.

5. A method of preparing a dual-loaded hydroxyapatite / ZIF composite anticorrosive filler according to any one of claims 1 to 4, characterized in that: It comprises the following steps: (1) Dissolve and mix calcium nitrate tetrahydrate, ammonium dihydrogen phosphate, urea and deionized water, then perform hydrothermal reaction at 110-120 ℃ for 2-4 h, and then perform centrifugal washing to obtain the hydroxyapatite nanosheet; (2) Ultrasonically disperse the above hydroxyapatite nanosheet in deionized water, then add tannic acid and mix uniformly, then adjust the pH to weak alkalinity with tris-hydroxymethyl aminomethane solution, then perform stirring reaction at room temperature for 4-6 h, and then perform centrifugal washing and freeze drying to obtain the tannic acid modified hydroxyapatite nanosheet; (3) Ultrasonically disperse the above tannic acid modified hydroxyapatite nanosheet in methanol, then sequentially add methanol solution of zinc nitrate hexahydrate, methanol solution of 2-amino benzothiazole and methanol solution of 2-methyl imidazole, then perform stirring reaction at room temperature, then perform centrifugal and drying to obtain the double-loaded hydroxyapatite / ZIF composite anticorrosive filler.

6. Application of the double-loaded hydroxyapatite / ZIF composite anticorrosive filler in any one of claims 1 to 4 in the preparation of an anticorrosive organic resin coating composition.

7. Use according to claim 6, wherein: The raw materials of the anticorrosive organic resin coating composition comprise an organic resin base material.

8. Use according to claim 7, wherein: The organic resin base material is selected from epoxy resin, polyurethane and polyester resin.

9. A corrosion protective organic resinous coating composition characterized by: The raw materials thereof comprise an organic resin base material and the double-loaded hydroxyapatite / ZIF composite anticorrosive filler in any one of claims 1 to 4.

10. A preservative organic resinous coating composition as in Claim 9, characterized by: The organic resin base material is selected from epoxy resin, polyurethane and polyester resin.

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