Application of zinc nanowires instead of zinc powder in the preparation of anti-corrosion coatings

Abstract

The present invention relates to the use of zinc nanowires to replace zinc powder in the preparation of anti-corrosion coatings, zinc-rich anti-corrosion coatings containing zinc nanowires, zinc-rich anti-corrosion coatings formed by the zinc-rich anti-corrosion coatings and preparation methods thereof, and devices containing the zinc-rich anti-corrosion coatings. By replacing micron-sized spherical zinc powders with zinc nanowires, the content of metallic zinc can be reduced while ensuring the conductivity of the coating, and while reducing the zinc content, equivalent or better conductivity and better corrosion resistance can be provided.

Description

Technical Field

[0001] The present invention relates to the technical field of zinc-rich anti-corrosion coatings, and specifically to the use of zinc nanowires instead of zinc powder in the preparation of anti-corrosion coatings, zinc-rich anti-corrosion coatings containing zinc nanowires, zinc-rich anti-corrosion coatings formed by the zinc-rich anti-corrosion coatings and preparation methods thereof, and devices comprising the zinc-rich anti-corrosion coatings. Background Art

[0002] Zinc-rich primer is a commonly used coating in the field of anti-corrosion and heavy-duty anti-corrosion. It is widely used in various steel structure coatings, such as bridges, containers, towers, ship hulls, building steel structures, etc. According to the different base materials, zinc-rich primers are often divided into organic zinc-rich primers and inorganic zinc-rich primers. Its anti-corrosion mechanism is the cathodic protection method of sacrificial anode, which sacrifices metal zinc in a corrosive environment to protect the base material. Therefore, the zinc-rich coating needs to have good conductivity and maintain good electrical contact with the base material to play the role of sacrificial anode.

[0003] At present, zinc-rich coatings mostly use micron-sized spherical zinc powder as a conductive medium. These zinc powders are wrapped in non-conductive polymer resins, and the actual utilization rate of zinc powder is greatly limited. According to the chemical industry standard HG / T 3668-2020, the content of metallic zinc in the non-volatile matter of zinc-rich primers is ≥60%, ≥70%, ≥80%, and can be divided into Class 3, Class 2, and Class 1. However, as the content of spherical zinc powder increases, the cost of zinc-rich coatings increases, the weight of coatings increases, and the utilization rate of zinc powder is low. Moreover, if the zinc powder content is too high, the adhesion of the coating will deteriorate and it will be easy to fall off, causing the anti-corrosion coating attached to the metal surface to need to be replaced frequently, resulting in high production costs and equipment maintenance costs, which is not conducive to sustainable development. Summary of the invention

[0004] The present invention is dedicated to solving the problems of high zinc powder content, heavy coating, low zinc powder utilization rate, poor coating adhesion, short service life and the like in existing anti-corrosion coating materials, proposes a new design idea and preparation method for anti-corrosion coatings, and experimental studies have found that replacing micron-sized spherical zinc powder with zinc nanowires can reduce the content of metallic zinc while ensuring the conductivity of the coating, thereby significantly improving the above-mentioned problems and completing the present invention.

[0005] In one aspect, the present invention provides the use of zinc nanowires to replace zinc powder in the preparation of zinc-rich anticorrosion coatings. By using zinc nanowires to replace zinc powder, it is possible to provide equivalent or better conductivity and better corrosion resistance while reducing the zinc content.

[0006] In another aspect, the present invention provides a zinc-rich anti-corrosion coating, which comprises zinc nanowires as a conductive medium. In particular, the zinc-rich anti-corrosion coating of the present invention does not contain zinc powder.

[0007] In the present invention, zinc nanowires refer to linear metal zinc with a diameter of 5-1000 nm, for example, the average diameter of the zinc nanowires can be 10-500 nm, 20-200 nm, such as 30, 40, 50, 60, 70, 80, 90, 100, 120, 150, 160, 170, 180, 190 nm, etc. There is no particular limitation on the length of the zinc nanowires, for example, the length can be 1 μm or more, 5 μm or more, such as 1-50 μm, 2-30 μm, etc.

[0008] In some embodiments, the zinc-rich anti-corrosion coating of the present invention comprises: a film-forming base material and zinc nanowires.

[0009] In some embodiments, the zinc-rich anti-corrosion coating of the present invention comprises: 20-70%, in particular 30-60%, of zinc nanowires, based on the total weight of the film-forming base material and the zinc nanowires.

[0010] In some embodiments, the zinc-rich anti-corrosion coating of the present invention comprises: 100 parts by weight of a film-forming binder, and 30-200 parts by weight, particularly 40-150 parts by weight, for example 50, 60, 70, 80, 90, 100, 110, 120, 130, 140 parts by weight of zinc nanowires.

[0011] The film-forming base material may be any film-forming base material suitable for zinc-rich anticorrosive coatings, including but not limited to epoxy resin, chlorinated rubber, vinyl resin, polyurethane resin, silicone resin (such as tetraethyl orthosilicate), etc.

[0012] In some embodiments, the film-forming base is an epoxy resin and a curing agent thereof. In this case, the epoxy resin and the curing agent thereof are stored separately and mixed together before use. The zinc nanowires can be stored separately or mixed into the epoxy resin.

[0013] The epoxy resin may include, but is not limited to, bisphenol A epoxy resin, novolac epoxy resin, aliphatic epoxy resin, glycidylamine epoxy resin, and the like.

[0014] The curing agent includes an amine curing agent, such as a primary amine curing agent, a secondary amine curing agent, an amide curing agent, an aromatic amine curing agent, an alicyclic amine curing agent, a fatty amine curing agent, etc., but is not limited thereto.

[0015] The zinc nanowires may be commercially available or prepared by any suitable method. The present invention is not limited thereto. For example, the zinc nanowires may be prepared by chemical methods (e.g., alkyl zinc cracking method), vapor deposition method, electrochemical deposition method, etc. Figure 1 The left picture shows a zinc nanowire prepared by the alkyl zinc cracking method, the middle picture shows a zinc nanowire prepared by vapor deposition, and the right picture shows a zinc nanowire prepared by electrochemical deposition.

[0016] According to the needs, the zinc-rich anticorrosive coating of the present invention may further include additives, including but not limited to defoamers, anti-settling agents, plasticizers, anti-rust pigments, film-aiding agents, barrier sheets, etc., but not limited thereto. The amount of additives and their selection range are within the scope of those skilled in the art, and the present invention will not be described in detail to avoid blurring the main innovative concept of the present invention.

[0017] In another aspect, the present invention provides a zinc-rich anti-corrosion coating, which is formed by the zinc-rich anti-corrosion paint according to the present invention.

[0018] In another aspect, the present invention provides a method for forming a zinc-rich anti-corrosion coating using the zinc-rich anti-corrosion coating of the present invention, comprising:

[0019] (1) providing a substrate;

[0020] (2) The zinc-rich anti-corrosion coating of the present invention is applied on a substrate and cured, thereby forming a zinc-rich anti-corrosion coating on the substrate.

[0021] The substrate includes but is not limited to carbon steel, stainless steel, cast iron and devices or equipment prepared therefrom.

[0022] There is no particular limitation on the method for applying the zinc-rich anticorrosive coating of the present invention, and any suitable method may be used, such as scraping, spraying, brushing, rolling, dipping, and composite film-forming processes, but not limited thereto.

[0023] In yet another aspect, the present invention provides a device comprising a zinc-rich anti-corrosion coating formed by the zinc-rich anti-corrosion coating according to the present invention.

[0024] The device is not particularly limited and can be any device that requires anti-corrosion function provided by zinc-rich anti-corrosion coating, such as ship steel decks, offshore steel structures, storage tanks, bridges, TV towers, containers, construction machinery, ships, cars, bicycles, etc., but not limited to these.

[0025] Beneficial Effects

[0026] Compared with common zinc-rich anti-corrosion coatings, the zinc-rich anti-corrosion coatings containing zinc nanowires of the present invention have less metallic zinc content, and the coating prepared by the present invention is lighter under the same coating area.

[0027] Compared with common zinc-rich anti-corrosion coatings, the coating prepared by the zinc-rich anti-corrosion coating containing zinc nanowires of the present invention has excellent conductivity and can provide more stable and longer-lasting cathodic protection.

[0028] Compared with ordinary zinc-rich anti-corrosion coatings, the zinc nanowire anti-corrosion coating in the present invention has a higher utilization rate of zinc. The zinc nanowire anti-corrosion coating prepared by the present invention consumes less zinc and obtains corrosion resistance similar to that of a coating containing a higher content of spherical zinc powder.

[0029] The present invention uses zinc nanowires as anode sacrificial materials and a film-forming base material as a carrier to prepare a zinc nanowire anticorrosion coating. Compared with ordinary anticorrosion coatings containing zinc powder, the coating prepared by the present invention has a lower zinc content; under the same coating volume, the coating prepared by the present invention has a smaller mass; and the prepared coating containing zinc nanowires has excellent electrical conductivity and corrosion resistance, improves the utilization rate of zinc in the zinc-rich anticorrosion coating, and will further improve the quality of the zinc-rich anticorrosion coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The left picture shows a zinc nanowire synthesized by chemical means, the middle picture shows a zinc nanowire prepared by vapor deposition, and the right picture shows a zinc nanowire prepared by electrochemical deposition.

[0031] Figure 2 The left picture is a scanning electron microscope photograph of the surface and cross-section of the coating of Comparative Example 5, and the right picture is a scanning electron microscope photograph of the surface and cross-section of the coating of Example 4.

[0032] Figure 3 The resistance test results of the zinc-rich anti-corrosion coatings prepared in Comparative Examples 1-7 and Examples 1-6 are shown.

[0033] Figure 4 The salt spray test results of the zinc-rich anti-corrosion coatings prepared in Comparative Examples 2 and 5 and Examples 2 and 4 are shown. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below through specific implementation modes, but the present invention is not limited to the following embodiments.

[0035] Reagents:

[0036] Spherical zinc powder was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., 600 mesh, purity 99.99% (article number: Z112688).

[0037] The resin was epoxy resin E-51 (Cat. No.: E871957) purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0038] The epoxy curing agent is an amine curing agent (article number: A875180) purchased from Shanghai MacLean Biochemical Technology Co., Ltd., with an amine value of 600-700 mg KOH / g and a viscosity (25° C.): 50-120 mPa.s.

[0039] Preparation Example: Preparation of Zinc Nanowires

[0040] The zinc nanowires were prepared by alkyl zinc cracking method, and the specific process is as follows.

[0041] A solution of diethylzinc dissolved in n-hexane (1 mol / L) was added to the reaction flask, and then a solution of titanium tetrabromide in n-hexane solution (0.034 mol / L) was added as a catalyst, the volume ratio of diethylzinc solution to titanium tetrabromide solution was 2:1, and the mixture was stirred at 70°C for 24 hours. Then, the prepared zinc nanowires were washed with n-hexane, tetrahydrofuran and isopropanol in turn, vacuum dried and stored in an inert gas environment for later use.

[0042] The prepared zinc nanowires Figure 1 (Left) As shown, the average diameter of zinc nanowires is about 80nm and the average length is about 30μm.

[0043] Comparative Example 1

[0044] (1) Add spherical zinc powder to epoxy resin solution, stir to make it uniformly dispersed, then add amino curing agent and mix uniformly. The above epoxy resin is 80 parts by weight, the amino curing agent is 20 parts by weight, and the zinc powder is 100 parts by weight to prepare a zinc-rich anticorrosive coating with a zinc content of 50wt%.

[0045] (2) The carbon steel was polished with 400 mesh, 800 mesh, and 1200 mesh sandpaper in sequence, cleaned with water and ethanol, and dried for later use;

[0046] (3) The zinc-rich anti-corrosion coating prepared in (1) is uniformly applied to the carbon steel substrate described in (2) by scraping to form a coating with a thickness of about 80 μm ± 5 μm, and then cured at room temperature, thereby forming a zinc-rich anti-corrosion coating on the carbon steel substrate.

[0047] Comparative Examples 2-7

[0048] A zinc-rich anti-corrosion coating was formed on a carbon steel substrate in the same manner as in Comparative Example 1, except that the mass ratio of zinc powder, epoxy resin and amino curing agent was changed according to Table 1 to obtain a zinc-rich anti-corrosion coating.

[0049] Table 1 Mass ratio of zinc powder, epoxy resin, amino curing agent and zinc content in coating

[0050] Comparative Example Zinc powder Epoxy resin Amino curing agent Zinc content (wt%) 2 7.5 4 1 60 3 11.67 4 1 70 4 15 4 1 75 5 20 4 1 80 6 28.33 4 1 85 7 45 4 1 90

[0051] Examples 1-6

[0052] A zinc-rich anticorrosion coating was formed on a carbon steel substrate in the same manner as in Comparative Example 1, except that zinc nanowires were used instead of zinc powder and the mass ratio of zinc nanowires, epoxy resin, and amino curing agent was changed according to Table 2.

[0053] Table 2 Mass ratio of zinc nanowires, epoxy resin, amino curing agent and zinc content in coatings

[0054] Example Zinc nanowires Epoxy resin Amino curing agent Zinc content (wt%) 1 2.14 4 1 30 2 3.33 4 1 40 3 4.09 4 1 45 4 5 4 1 50 5 6.11 4 1 55 6 7.5 4 1 60

[0055] Experimental Example 1

[0056] The surface and cross section of the coating samples of Comparative Example 5 and Example 4 were observed using a scanning electron microscope (Themo Scientific) to compare the microscopic morphology. Figure 2 .

[0057] like Figure 2 As shown, the coating thickness of Example 4 and Comparative Example 5 is 80um±5um. In the coating of Comparative Example 5, the zinc powder is evenly dispersed in the epoxy resin, and the sample contrast is uniform, without obvious charge accumulation, indicating that a good conductive path is formed between the zinc powders; similarly, in the coating of Example 4, the zinc nanowires are also evenly dispersed in the resin, the sample contrast is uniform, and there is no obvious charge accumulation, indicating that a good conductive path is also formed between the zinc nanowires in Example 4, which is conducive to the electrochemical anti-corrosion effect, which is also consistent with the coating resistance test results in Experimental Example 2 below.

[0058] Experimental Example 2

[0059] The zinc-rich anticorrosion coatings of Comparative Examples 1-7 and Examples 1-6 were electrically tested using a two-electrode method as follows:

[0060] The electrical testing equipment is a digital source meter. The cured Examples 1-7 and Comparative Examples 1-6 are clamped with electrode clamps, voltage is applied, and resistance is read. Five areas of each sample are tested, and the average value is taken as the resistance value of the sample, and an error value is given.

[0061] Figure 3 The coating resistance curves of the zinc-rich anti-corrosion coatings of the comparative example and the embodiment are shown as a function of the zinc content. In the zinc-rich anti-corrosion coating of the comparative example, when the zinc powder content is greater than 70wt%, the coating resistance value gradually decreases as the zinc powder content increases. In the zinc-rich anti-corrosion coating of the embodiment, when the zinc nanowire content is greater than 45wt%, the coating resistance value gradually decreases as the zinc powder content increases, proving that the zinc-rich anti-corrosion coating using zinc nanowires according to the present invention can form a good conductive path at a lower zinc loading.

[0062] Experimental Example 3

[0063] According to the national standard GB / T10125-2021, the zinc-rich anti-corrosion coatings of Comparative Examples 2 and 5 and Examples 2 and 4 were subjected to neutral salt spray tests as follows, the test environment was formed by atomization of 5% sodium chloride solution, and the test temperature was 25±2° C. The sample placement angle was 20±2° with respect to the vertical direction.

[0064] The scratches on the test samples meet the requirements of the national standard GB / T10125-2021. The scratches are prepared by an Elcometer 1538 salt spray scoring knife. All scratches are greater than 2 cm from each edge of the test plate, and the scratch width is 0.5 mm.

[0065] During the test, observations were made on the 1st, 5th, 10th, 15th and 20th days. Figure 4 As shown. During the entire test process, no pitting, cracking, blistering and other phenomena occurred in the test samples. The zinc-rich anti-corrosion coating containing 60wt% zinc powder in Comparative Example 2 showed obvious corrosion products on the first day, and the corrosion products gradually increased as the test time increased. The zinc-rich anti-corrosion coating containing 40wt% zinc nanowires according to Example 2 of the present invention did not show corrosion products on the first day, but showed corrosion products on the third day, and the corrosion products gradually increased over time. The zinc-rich anti-corrosion coatings of Comparative Example 5 and Example 4 did not show obvious corrosion products until the 10th day. Compared with the zinc-rich anti-corrosion coating containing 80wt% zinc powder in Comparative Example 5, the zinc-rich coating with a zinc nanowire content of 50wt% in Example 4 can achieve similar corrosion resistance. From the above results, it can be seen that the zinc-rich anti-corrosion coating using zinc nanowires according to the present invention has better anti-corrosion performance than the zinc-rich anti-corrosion coating using zinc powder, and reduces the amount of metallic zinc.

Claims

1. Application of zinc nanowires to replace zinc powder in the preparation of zinc-rich anti-corrosion coatings, wherein: The zinc nanowires were prepared as follows: A 1 mol / L solution of diethylzinc dissolved in n-hexane was added to a reaction flask, and then a 0.034 mol / L solution of titanium tetrabromide in n-hexane solution was added as a catalyst, the volume ratio of the diethylzinc solution to the titanium tetrabromide solution was 2:1, and the mixture was stirred at 70°C for 24 hours. The prepared zinc nanowires were then washed with n-hexane, tetrahydrofuran and isopropanol in turn, vacuum dried and stored in an inert gas environment.

2. A zinc-rich anticorrosive coating comprising zinc nanowires as a conductive medium, wherein: The zinc nanowires were prepared as follows: A 1 mol / L solution of diethylzinc dissolved in n-hexane was added to a reaction flask, and then a 0.034 mol / L solution of titanium tetrabromide in n-hexane solution was added as a catalyst, the volume ratio of the diethylzinc solution to the titanium tetrabromide solution was 2:1, and the mixture was stirred at 70°C for 24 hours. The prepared zinc nanowires were then washed with n-hexane, tetrahydrofuran and isopropanol in turn, vacuum dried and stored in an inert gas environment.

3. The zinc-rich anticorrosive coating according to claim 2, which does not contain zinc powder. The zinc-rich anti-corrosion coating according to claim 2 , comprising: a film-forming base material and zinc nanowires.

5. The zinc-rich anti-corrosion coating according to claim 4, comprising: 20-70% of zinc nanowires based on the total weight of the film-forming base material and the zinc nanowires.

6. The zinc-rich anti-corrosion coating according to claim 4, comprising: 30-60% of zinc nanowires based on the total weight of the film-forming base material and the zinc nanowires.

7. The zinc-rich anticorrosive coating according to claim 4, comprising: 100 parts by weight of a film-forming base material, and 30-200 parts by weight of zinc nanowires.

8. The zinc-rich anticorrosive coating according to claim 4, comprising: 100 parts by weight of a film-forming base material, and 40-150 parts by weight of zinc nanowires.

9. The zinc-rich anticorrosive coating according to claim 4, wherein: The film-forming base material is selected from epoxy resin, chlorinated rubber, vinyl resin, polyurethane resin and silicone resin.

10. A zinc-rich anti-corrosion coating, formed by the zinc-rich anti-corrosion paint according to any one of claims 2 to 9.

11. A method for forming a zinc-rich anti-corrosion coating using the zinc-rich anti-corrosion paint according to any one of claims 2 to 9, comprising: (1) Providing a substrate; (2) The zinc-rich anti-corrosion coating according to any one of claims 2 to 9 is applied on a substrate and cured to form a zinc-rich anti-corrosion coating on the substrate.

12. A device comprising a zinc-rich anti-corrosion coating formed by the zinc-rich anti-corrosion coating according to any one of claims 2 to 9.

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