PH response type metal organic framework corrosion inhibition material, preparation method and corrosion-resistant epoxy coating

Abstract

The invention provides a pH response type metal organic framework corrosion inhibition material, a preparation method and a corrosion-resistant epoxy coating, and belongs to the field of corrosion-resistant epoxy coatings. The corrosion inhibition material comprises a tea extract and a pH response type metal-organic framework material, wherein the tea extract is loaded on the pH response type metal-organic framework material; and the pH response type metal-organic framework material is a ZIF-8 crystal. After the corrosion inhibition material and epoxy resin are mixed and cured, a corrosion-resistant epoxy coating can be obtained, and the corrosion-resistant epoxy coating can be applied to occurrence of steel corrosion and can inhibit the progress of steel corrosion.

Description

Technical Field

[0001] The present invention belongs to the field of corrosion-resistant epoxy coatings, and particularly relates to a pH-responsive metal-organic framework corrosion inhibitor material, a preparation method thereof, and a corrosion-resistant epoxy coating. Background Art

[0002] In modern industry and life, the widespread use of metal materials has made the anti-corrosion problem increasingly prominent. Although traditional anti-corrosion coatings can play a protective role to a certain extent, with the increasingly harsh use environment, their anti-corrosion performance gradually fails to meet the requirements. The anti-corrosion coating technology field has been seeking innovative solutions to improve the anti-corrosion effect, durability, and environmental friendliness of coatings.

[0003] Corrosion inhibitors have been widely studied due to their low dosage, good effect, and simple construction. However, although organic corrosion inhibitors have gradually replaced inorganic corrosion inhibitors and shown many advantages, they still face a series of challenges in practical applications. Different metal materials and complex and changeable use environments, such as extreme conditions like high temperature, high pressure, and high acid-base concentration, pose strict requirements on the adaptability of organic corrosion inhibitors. In some special industrial fields, such as deep-sea oil exploitation, the low temperature, high pressure, and high salt environment in the deep sea greatly reduces the corrosion inhibition effect of conventional organic corrosion inhibitors, which urgently requires the development of organic corrosion inhibitors with special properties and structures to meet these special working conditions. In addition, with the continuous upgrading of environmental protection standards, the requirements for environmental protection indicators such as the degradability and non-toxicity of organic corrosion inhibitors are also getting higher and higher. How to prepare organic corrosion inhibitors using green and environmentally friendly synthesis processes and raw materials while ensuring the corrosion inhibition performance has become another difficult problem that current researchers urgently need to overcome.

[0004] Plants contain various organic compounds with corrosion inhibition properties, such as alkaloids, flavonoids, tannins, polysaccharides, and terpenoids. Tea extracts mainly contain components such as tea polyphenols, caffeine, and polysaccharides, and can form complexes with iron ions on the surface of metals (such as steel, etc.) through their phenolic hydroxyl groups. This complex forms a protective film on the metal surface, preventing further contact between the corrosion medium (such as water, oxygen, chloride ions, etc.) and the metal matrix, and playing a corrosion inhibition role.

[0005] Metal-organic framework materials (MOFs), as a new type of porous material, have a high specific surface area, adjustable pore structure, and rich chemical properties. In recent years, MOFs have shown great application potential in fields such as gas adsorption, catalysis, and separation. In the field of anti-corrosion coating technology, MOFs are also considered a promising additive, and can enhance the anti-corrosion performance of coatings through their unique structure and properties. Summary of the Invention

[0006] The object of the present invention is to provide a pH-responsive metal-organic framework corrosion inhibitor material, a preparation method thereof, and a corrosion-resistant epoxy coating, which can be applied to the occurrence of steel corrosion and inhibit the process of steel corrosion.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A pH-responsive metal-organic framework corrosion inhibitor material, comprising a tea extract and a pH-responsive metal-organic framework (MOFs) material, wherein the tea extract is loaded on the pH-responsive metal-organic framework (MOFs) material;

[0009] The pH-responsive metal-organic framework (MOFs) material is a ZIF-8 crystal.

[0010] Preferably, the extraction method of the tea extract is as follows: the tea is crushed and wrapped with filter paper, deionized water and ethanol are used as solvents for extraction, the extract is concentrated, and then evaporated to a mass-volume ratio of 1 g∶(0.5 - 1) mL, filtered, and dried to obtain the tea extract, abbreviated as GTE.

[0011] Preferably, the preparation method of the ZIF-8 crystal is as follows: Zn(NO3)2·6H2O, 2-methylimidazole and dimethylacetamide (DMF) are placed in a reaction kettle with a polytetrafluoroethylene lining. After the reaction kettle is sealed, it is placed in a programmable muffle furnace for heating. The obtained crystals are washed and dried to obtain ZIF-8 crystals.

[0012] The present invention also provides a preparation method of a pH-responsive metal-organic framework corrosion inhibitor material, comprising:

[0013] Adding ZIF-8 to the methanol solution of GTE, stirring, then centrifuging, collecting the precipitate, and drying in vacuum to obtain the pH-responsive metal-organic framework corrosion inhibitor material GTE@ZIF-8.

[0014] Preferably, the stirring temperature is room temperature and the stirring time is 12 - 16 h.

[0015] Preferably, the mass ratio of GTE to ZIF-8 in the methanol solution of GTE is 5∶8.

[0016] The present invention also provides an epoxy coating prepared from the above pH-responsive metal-organic framework corrosion inhibitor material.

[0017] The present invention also provides a preparation method of an epoxy coating, comprising:

[0018] After grinding the GTE@ZIF-8 material, adding a diluent, and then dispersing the epoxy resin in the diluent and mixing it evenly with the GTE@ZIF-8 material to obtain a mixture;

[0019] Add a curing agent to the above mixture and mix evenly to obtain an epoxy coating;

[0020] Coat the epoxy coating on the surface of the substrate metal and cure it at room temperature to obtain an epoxy coating.

[0021] Preferably, the epoxy resin is E51 epoxy resin, the curing agent is alicyclic amine MFA-75, and the diluent is acetone.

[0022] Preferably, the addition amount of GTE@ZIF- is 0.1-0.5% of the total mass of the epoxy resin and the curing agent.

[0023] Advantages of the present invention

[0024] The present invention provides a pH-responsive metal-organic framework corrosion inhibitor material, a preparation method and a corrosion-resistant epoxy coating. The corrosion inhibitor material combines the environmentally friendly and green tea extract and the pH-responsive MOFs material to construct a highly efficient and highly selective corrosion inhibitor material. After mixing and curing the corrosion inhibitor material with epoxy resin, a corrosion-resistant epoxy coating can be obtained, which can be applied to the occurrence of steel corrosion and inhibit the process of steel corrosion. The corrosion-resistant epoxy coating has a wide range of applications and can be used for steel structures in the fields of ocean, chemical industry, petroleum, natural gas, electric power, transportation, etc. Description of the drawings

[0025] Figure 1 Release curve of GTE@ZIF-8 prepared in Example 1 under different pH buffer solution conditions;

[0026] Figure 2 Photographs of the corrosion conditions of the products obtained in Examples 2-4 and Comparative Examples 1-3 of the present invention immersed in a NaCl solution (simulating seawater). Detailed implementation manners

[0027] A pH-responsive metal-organic framework corrosion inhibitor material, comprising a tea extract and a pH-responsive metal-organic framework (MOFs) material, wherein the tea extract is loaded on the pH-responsive metal-organic framework (MOFs) material;

[0028] The pH-responsive metal-organic framework (MOFs) material is a ZIF-8 crystal.

[0029] According to the present invention, the extraction method of the tea extract is preferably as follows: After crushing the tea leaves, wrap them with filter paper, use deionized water and ethanol as solvents (the ratio is 2:1), and carry out extraction. The extraction time is preferably 36 - 48h. Concentrate the extract, and then evaporate it to a mass - volume ratio of 1g∶(0.5 - 1)mL, filter, and the filtrate is dried to obtain the tea extract, abbreviated as GTE. The volume ratio of the deionized water to ethanol is preferably 2:1.

[0030] According to the present invention, the preparation method of the ZIF - 8 crystal is as follows: Put Zn(NO3)2·6H2O, 2 - methylimidazole, and dimethylacetamide (DMF) into a reaction kettle with a polytetrafluoroethylene liner. Control the molar ratio of Zn(NO3)2·6H2O to 2 - methylimidazole to be 2:3. After sealing the reaction kettle, put it into a programmable muffle furnace, and preferably heat it to 130℃ at a rate of 5℃ / min and react for 10h. Wash the obtained crystal with acetone 3 times, and put it into a vacuum oven to dry at 80℃ for 8 - 10h to obtain the ZIF - 8 crystal.

[0031] The present invention also provides a preparation method of a pH - responsive metal - organic framework corrosion - inhibiting material, including:

[0032] Add ZIF - 8 to the methanol solution of GTE, preferably stir at room temperature for 12 - 16 hours, then centrifuge at 6000 - 8000rpm for 15 - 20 minutes, collect the precipitate, and then vacuum - dry at 100℃ to remove the residual solvent to obtain the pH - responsive metal - organic framework corrosion - inhibiting material GTE@ZIF - 8. The mass of GTE in mg: the mass of ZIF - 8 in mg: the volume of methanol in mL is preferably 5∶8∶12.

[0033] The present invention also provides an epoxy coating prepared from the above - mentioned pH - responsive metal - organic framework corrosion - inhibiting material.

[0034] The present invention also provides a preparation method of an epoxy coating, including:

[0035] After grinding the GTE@ZIF - 8 material, add a diluent, and then disperse the epoxy resin in the diluent and mix it evenly with the GTE@ZIF - 8 material to obtain a mixture; the epoxy resin is preferably E51 epoxy resin, and the diluent is preferably acetone; the addition amount of GTE@ZIF - is preferably 0.1 - 0.5% of the total mass of the epoxy resin and the curing agent.

[0036] Add the curing agent to the above - mentioned mixture and mix it evenly to obtain an epoxy coating. The curing agent is preferably alicyclic amine MFA - 75, and the mass ratio of the epoxy resin to the curing agent is preferably 2.5:1;

[0037] The epoxy coating was applied to the surface of the substrate metal with a spray gun or a brush, and the GTE@ZIF-8 composite epoxy coating was obtained after curing at room temperature.

[0038] The following further describes the specific implementation manners of the present invention in conjunction with the drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, so that those skilled in the art can better understand and utilize the present invention, rather than limiting the protection scope of the present invention.

[0039] Example 1 Preparation of GTE@ZIF-8 Corrosion Inhibitor

[0040] (1) 500 g of tea leaves were crushed and wrapped with filter paper, then placed in a 5 L three-necked flask equipped with a condensing device. 2.5 L of a mixed solvent of deionized water and ethanol (mass ratio 2:1) was added and heated under reflux for 48 h. After the process ended, it was transferred to a beaker to concentrate the extract, and then evaporated until the water level dropped to 400 mL, filtered, and the filtrate was dried in an oven at 60 °C to obtain the tea leaf extract, abbreviated as GTE;

[0041] (2) 5.94 g of Zn(NO3)2·6H2O, 2.46 g of 2-methylimidazole and 70 mL of dimethylacetamide (DMF) were placed in a reaction kettle with a polytetrafluoroethylene lining. After the reaction kettle was sealed, it was placed in a programmable muffle furnace and heated to 130 °C at a rate of 5 °C / min for reaction for 10 h. After cooling, the obtained crystals were washed 3 times with acetone and dried in a vacuum oven at 80 °C for 8 h to obtain ZIF-8 crystals.

[0042] (3) 50 mg of the GTE prepared in step (1) was added to 120 mL of methanol solution. After dissolution, 80 mg of the ZIF-8 prepared in step (2) was added, and stirred at room temperature for 14 h, then centrifuged at 7000 rpm for 18 min, the precipitate was collected, and then dried under vacuum at 100 °C to remove the residual solvent, obtaining the pH-responsive metal-organic framework corrosion inhibitor GTE@ZIF-8 loaded with GTE.

[0043] Example 2

[0044] A preparation method of a pH-responsive corrosion-resistant epoxy coating, comprising the following steps:

[0045] (1) 10 mg of the pH-responsive metal-organic framework corrosion inhibitor GTE@ZIF-8 prepared in Example 1 was added to 5 mL of acetone, and then 10 g of epoxy resin E51 was dispersed in a diluent and mixed evenly with the GTE@ZIF-8 material to obtain a mixture.

[0046] (2) Add 4 g of the curing agent alicyclic amine MFA-75 to the mixture obtained in step (1), mix evenly, and finally apply the epoxy coating on the surface of the substrate metal with a brush (refer to GB / T 20777-2006 "Inspection and Preparation of Test Specimens of Paints and Varnishes"), and a GTE@ZIF-8 composite epoxy coating is obtained after curing at room temperature.

[0047] Example 3

[0048] A preparation method of a pH-responsive corrosion-resistant epoxy coating includes the following steps:

[0049] (1) Take 20 mg of the pH-responsive metal-organic framework corrosion inhibitor material GTE@ZIF-8 prepared in Example 1 and add it to 5 mL of acetone. Then disperse 10 g of epoxy resin E51 in a diluent and mix evenly with the GTE@ZIF-8 material to obtain a mixture.

[0050] (2) Add 4 g of the curing agent alicyclic amine MFA-75 to the mixture obtained in step (1), mix evenly, and finally apply the epoxy coating on the surface of the substrate metal with a brush (refer to GB / T 20777-2006 "Inspection and Preparation of Test Specimens of Paints and Varnishes"), and a GTE@ZIF-8 composite epoxy coating is obtained after curing at room temperature.

[0051] Example 4

[0052] A preparation method of a pH-responsive corrosion-resistant epoxy coating includes the following steps:

[0053] (1) Take 50 mg of the pH-responsive metal-organic framework corrosion inhibitor material GTE@ZIF-8 prepared in Example 1 and add it to 5 mL of acetone. Then disperse 10 g of epoxy resin E51 in a diluent and mix evenly with the GTE@ZIF-8 material to obtain a mixture.

[0054] (2) Add 4 g of the curing agent alicyclic amine MFA-75 to the mixture obtained in step (1), mix evenly, and finally apply the epoxy coating on the surface of the substrate metal with a brush (refer to GB / T 20777-2006 "Inspection and Preparation of Test Specimens of Paints and Varnishes"), and a GTE@ZIF-8 composite epoxy coating is obtained after curing at room temperature.

[0055] Comparative Example 1

[0056] The preparation method of BTA@ZIF-8 by using the traditional organic corrosion inhibitor benzotriazole (BTA) to replace GTE includes the following steps:

[0057] (1) 10 mg of BTA was added to 120 mL of methanol solution. After dissolution, 80 mg of self-made ZIF-8 was added, and the mixture was stirred at room temperature for 14 hours. Then, it was centrifuged at 7000 rpm for 18 minutes to collect the precipitate, and then vacuum-dried at 100 °C to remove the residual solvent, obtaining BTA@ZIF-8.

[0058] (2) 10 mg of the prepared BTA@ZIF-8 was taken and added to 5 mL of acetone. Then, 10 g of epoxy resin E51 was dispersed in the diluent and mixed evenly with the BTA@ZIF-8 material to obtain a mixture.

[0059] (3) 4 g of curing agent alicyclic amine MFA-75 was added to the mixture obtained in step (1) and mixed evenly. Finally, the epoxy coating was applied to the surface of the substrate metal with a brush (refer to GB / T 20777-2006 "Examination and Preparation of Samples of Paints and Varnishes"), and after curing at room temperature, a BTA@ZIF-8 composite epoxy coating was obtained.

[0060] Comparative Example 2

[0061] A preparation method of a corrosion-resistant epoxy coating includes the following steps:

[0062] (1) 10 mg of the prepared ZIF-8 was taken and added to 5 mL of acetone. Then, 10 g of epoxy resin E51 was dispersed in the diluent to obtain a mixture.

[0063] (2) 4 g of curing agent alicyclic amine MFA-75 was added to the mixture obtained in step (1) and mixed evenly. Finally, the epoxy coating was applied to the surface of the substrate metal with a brush (refer to GB / T 20777-2006 "Examination and Preparation of Samples of Paints and Varnishes"), and after curing at room temperature, a BTA@ZIF-8 composite epoxy coating was obtained.

[0064] Comparative Example 3

[0065] This comparative example provides an epoxy coating, and the difference from Example 1 is that: the formulation does not contain ZIF-8 and corrosion inhibitors. According to the method of Example 2, pure epoxy resin and curing agent were mixed and cured to obtain an epoxy coating to compare the effects of ZIF-8 and corrosion inhibitors on the epoxy coating.

[0066] Performance Test

[0067] To verify the pH-stimulus-responsive controlled release performance of the GTE@ZIF-8 prepared in Example 1, its pH-responsive release behavior was systematically evaluated under different pH buffer solution conditions (pH 3, 7, and 11), as shown in Figure 1As can be seen from the figure, the controllable release performance of GTE@ZIF-8 under different pH stimuli was verified. From the release curve, it can be seen that in the initial stage of immersion (the first 3 hours), it is the rapid release stage of GTE, and the release rate can reach more than 87%, which is crucial for metal corrosion protection. When corrosion occurs, the nano-container can promptly respond to the corrosion stimulus and release a large amount of corrosion inhibitor to effectively inhibit the corrosion reaction at the coating defects.

[0068] To detect the performance of the epoxy coatings prepared in the above 3 examples and 3 comparative examples, the prepared waterproof coatings were formed with reference to GB / T 20777-2006 "Examination and Preparation of Test Specimens of Paints and Varnishes", and then immersed in a 3.5 wt% NaCl solution (simulating seawater) to observe their corrosion conditions. The results are shown in the following figure:

[0069] As Figure 2 It can be seen that the pH-responsive metal-organic framework corrosion inhibitor material GTE@ZIF-8 shows a very significant corrosion inhibition effect after being added to the epoxy coating. By comparing Example 2 and Comparative Example 3, it can be found that after adding this corrosion inhibitor material, the corrosion rate of the coating is significantly slowed down, the degree of corrosion is greatly reduced, and the corrosion area no longer continues to expand, which well plays the role of protecting the substrate. Further comparing Example 3, 4 and Comparative Example 3, it can be learned that with the continuous increase of the addition amount of GTE@ZIF-8, its protection effect on the substrate is also significantly improved, which fully demonstrates the important influence of the addition amount of this corrosion inhibitor material on the anti-corrosion performance. Through the comparison between Example 2 and Comparative Example 1, compared with the traditional organic corrosion inhibitor benzotriazole (BTA) and GTE, their corrosion inhibition effects are generally similar. However, if the corrosion effects after soaking for 3 days are focused on comparison, it can be found that the corrosion inhibition effect of GTE is more prominent. It can protect the substrate more quickly when corrosion just begins, showing unique advantages in timeliness. And through the comparison between Example 2 and Comparative Example 2, it can be known that when only ZIF-8 is added, although it does not play an ideal corrosion inhibition role on the substrate and the degree of corrosion shows a gradually increasing trend, due to the unique crystal structure and large specific surface area of ZIF-8, relying on these characteristics, it can be evenly dispersed and interconnected in the epoxy resin, and then a network structure similar to a physical barrier is constructed. It is the existence of this network structure that enables it to delay the penetration of corrosion media to a certain extent and plays a certain role in hindering the development of corrosion. Compared with Comparative Example 3, the degree of corrosion in Comparative Example 2 has indeed been improved to a certain extent.

[0070] Finally, it should be noted that in the above embodiments, the best implementation mode of the present invention is briefly described. For those of ordinary skill in the art, any changes, modifications, substitutions, etc. made to the embodiments of the present invention under the inspiration of the principles of the present invention fall within the protection scope of the present invention.

Claims

1. A pH-responsive metal organic framework corrosion inhibition material, characterized in that: It comprises tea extract and a pH-responsive metal-organic framework material, wherein the tea extract is loaded on the pH-responsive metal-organic framework material; The pH-responsive metal-organic framework material is ZIF-8 crystal.

2. A pH-responsive metal organic framework corrosion inhibition material according to claim 1, characterized in that: The extraction method of the tea extract is as follows: crush the tea leaves and wrap them with filter paper, use deionized water and ethanol as solvents for extraction, concentrate the extract, and then evaporate it to a mass volume ratio of 1g: (0.5-1)mL, filter it, and dry it to obtain the tea extract, referred to as GTE.

3. A pH-responsive metal organic framework corrosion inhibition material according to claim 1, characterized in that: The preparation method of the ZIF-8 crystal is as follows: Zn(NO3)2·6H2O, 2-methylimidazole and dimethylacetamide are placed in a reactor lined with polytetrafluoroethylene, the reactor is sealed and placed in a programmable muffle furnace for heating, and the obtained crystal is washed and dried to obtain the ZIF-8 crystal.

4. The method for preparing a pH-responsive metal organic framework corrosion inhibition material according to claim 1, characterized in that: include: ZIF-8 was added to the methanol solution of GTE and stirred, and then centrifuged to collect the precipitate and vacuum dry it to obtain the pH-responsive metal organic framework corrosion inhibition material GTE@ZIF-8.

5. According to the method for preparing a pH-responsive metal organic framework corrosion inhibition material as described in claim 4, the stirring temperature is room temperature and the stirring time is 12-16 hours. 6 . The method for preparing a pH-responsive metal organic framework corrosion inhibition material according to claim 4 , wherein the mass ratio of GTE to ZIF-8 in the GTE methanol solution is 5:

8.

7. The epoxy coating prepared from the pH-responsive metal organic framework corrosion inhibition material according to claim 1.

8. The method for preparing an epoxy coating according to claim 7, characterized in that: include: After the GTE@ZIF-8 material is ground, a diluent is added, and then the epoxy resin is dispersed in the diluent and mixed evenly with the GTE@ZIF-8 material to obtain a mixture; Adding a curing agent into the above mixture and mixing evenly to obtain an epoxy coating; The epoxy coating is applied on the surface of the base metal and cured at room temperature to obtain the epoxy coating.

9. The method for preparing an epoxy coating according to claim 8, characterized in that: The epoxy resin is E51 epoxy resin, the curing agent is alicyclic amine MFA-75, and the diluent is acetone.

10. The method for preparing an epoxy coating according to claim 8, characterized in that: The amount of GTE@ZIF- added is 0.1-0.5% of the total mass of the epoxy resin and the curing agent.

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