High-silica zeolite / carbon nitride / polyurethane anti-corrosion coating and its preparation method and application

Abstract

A high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating and its preparation method and application relate to the technical field of coatings, and solve the problems of poor compatibility between organic and inorganic components, and unsatisfactory corrosion resistance and wear resistance in traditional metal anti-corrosion coatings. In the present invention, a high-silica zeolite / carbon nitride composite material is synthesized by an in-situ thermal polycondensation method using high-silica zeolite and dicyandiamide, and it is filled into waterborne polyurethane to obtain a high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating. The anti-corrosion coating realizes excellent corrosion resistance and wear resistance of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating by inhibiting the transfer of carriers in the metal, enhancing the charge migration resistance, blocking the contact between corrosion ions and the metal, and forming an effective shielding layer on the metal surface; in addition, after the anti-corrosion coating is damaged by external stimuli, the disulfide bonds in the polyurethane can be reversibly broken and connected through the catalytic action of carbon nitride to achieve self-healing. The present invention is applied to the anti-corrosion of metal surfaces.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly relates to a high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating and its preparation method and application. Background Art

[0002] As an industrial protection material, anti-corrosion coatings are widely used in the fields of concrete facility base surface protection, metal surface protection, and construction equipment protection, etc., aiming to improve the durability of facilities, extend the service life, and reduce maintenance costs. With the acceleration of the industrialization process, metal materials, especially steel, aluminum alloy, etc., are widely used in various buildings, mechanical equipment, and transportation tools. These metal surfaces are prone to oxidation, corrosion, etc. when exposed to harsh environments (such as humidity, corrosive gases, etc.) for a long time, seriously affecting their performance and safety. Therefore, the use of metal anti-corrosion coatings is particularly important.

[0003] Traditional metal anti-corrosion coatings mainly use organic resins as the main component. Common organic resins include epoxy resins, polyurethane (PU) resins, etc. These resins can form a strong protective film to effectively isolate the contact between the metal and corrosion factors (such as moisture, oxygen, acids and alkalis, etc.) in the external environment, achieving the purpose of anti-corrosion. However, in actual applications, the corrosion resistance effect of the organic resin coating is often limited by the nature of the organic resin itself. Therefore, inorganic fillers (such as clay, quartz powder, aluminum powder, etc.) are usually added to improve the corrosion resistance, wear resistance, and other specific properties of the organic resin coating. However, the compatibility problem between the inorganic filler and the organic resin seriously affects the stability of the coating. Inorganic fillers usually have low surface activity and poor binding force with organic resins, which leads to poor dispersion of the fillers during the coating process, easy precipitation or shedding, further reducing the anti-corrosion ability and wear resistance of the coating. For example, Chinese patent document CN108329797A discloses a graphene waterborne coating and its preparation method. This coating can slow down the reaction rate between the magnesium alloy substrate and water, reduce the corrosion of the magnesium alloy by water, and at the same time can increase the surface tension of the aluminum alloy, increase the surface wettability, and play a role in sealing the surface of the aluminum alloy, thereby improving the consistency of the coating appearance; however, the corrosion resistance and wear resistance effects of this coating need to be improved. Chinese patent document CN114369746A discloses a high-temperature aluminum alloy for floor heating pipes and its production process. The surface of the aluminum alloy pipe substrate is treated with a corrosion-resistant coating to improve the corrosion resistance and heat resistance of the aluminum alloy pipe substrate; and modified graphene is introduced to modify the coating to improve the heat dissipation of the silicone ceramic coating, but the wear resistance of this coating needs to be improved.

[0004] Therefore, a technical solution for developing a new organic-inorganic anti-corrosion coating is proposed to optimize the defects of current traditional metal anti-corrosion coatings in terms of corrosion resistance, wear resistance, and compatibility, providing a more reliable and economical protection solution for the industrial and construction fields. Summary of the Invention

[0005] To solve the problems of poor compatibility between organic and inorganic components, and unsatisfactory corrosion resistance and wear resistance of traditional metal anti-corrosion coatings, the present invention proposes a high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating, its preparation method, and application. The specific technical solution is as follows:

[0006] A high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating, by mass, comprises the following components in the following mass parts:

[0007] 1 part of high-silica zeolite / carbon nitride composite material and 100 parts of polyurethane;

[0008] Preferably, it further includes 0.01 - 1.2 parts of penetrant, 0.01 - 1 part of emulsifier, 0 - 0.05 parts of defoamer, 0 - 10 parts of film-forming aid, and 0 - 1 part of other additives;

[0009] The high-silica zeolite / carbon nitride composite material is synthesized by in-situ thermal polycondensation of high-silica zeolite and dicyandiamide; the mass ratio of high-silica zeolite to carbon nitride is 10 - 50:1, and the high-silica zeolite is hydrogen-type β zeolite (Hβ).

[0010] A preparation method of the above high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating includes the following steps:

[0011] S1: Add dicyandiamide and high-silica zeolite to deionized water, stir to mix evenly, then dry in an oven. After the sample is completely dry, transfer it to a crucible and place it in a muffle furnace. Heat up the muffle furnace and calcine the sample to undergo a thermal polycondensation reaction; after grinding the calcined composite material, wash it with absolute ethanol and deionized water, and dry it to obtain the high-silica zeolite / carbon nitride composite material;

[0012] S2: Mix the high-silica zeolite / carbon nitride composite material with polyurethane, ultrasonically treat the mixture, and then mechanically stir it to obtain the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating;

[0013] Furthermore, the carbon nitride is calcined from the precursor dicyandiamide. Among them, dicyandiamide is of analytical purity and does not require further purification; high-silica zeolite is of experimental purity and does not require further purification;

[0014] Furthermore, in the S1, the stirring time is 2 - 3 h and the rotation speed is 200 ppm;

[0015] Further, the drying temperature in S1 is 55 °C;

[0016] Further, the heating rate in S1 is 5 - 10 °C / min;

[0017] Further, the calcination temperature in S1 is 520 °C;

[0018] Further, the calcination time in S1 is 2 h;

[0019] Further, the mass ratio of the high-silica zeolite / carbon nitride composite to polyurethane in S2 is 1:100;

[0020] Further, the ultrasonic time in S2 is 30 min;

[0021] Further, the mechanical stirring time in S2 is 6 h.

[0022] An application of the above high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating for anti-corrosion of metal surfaces.

[0023] Compared with the prior art, the present invention solves the problems of poor compatibility between organic and inorganic components, and unsatisfactory corrosion resistance and wear resistance in traditional metal anti-corrosion coatings. The specific beneficial effects are as follows:

[0024] 1. Excellent structural stability: In the present invention, a high-silica zeolite / carbon nitride composite is synthesized by in-situ thermal polycondensation of high-silica zeolite and dicyandiamide, and is filled into waterborne polyurethane to obtain a high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating. First, the introduction of high-silica zeolite improves the catalytic activity of carbon nitride, and also enhances the structural stability of the anti-corrosion coating through its synergistic effect with carbon nitride; at the same time, the high surface area and pore structure of high-silica zeolite effectively improve the dispersibility of carbon nitride, preventing its aggregation in the polyurethane matrix, thus ensuring the uniform distribution of the high-silica zeolite / carbon nitride composite in the anti-corrosion coating, enhancing its compatibility, and further enhancing the mechanical strength, wear resistance and flexibility of the anti-corrosion coating; secondly, carbon nitride itself has a flaky structure, and the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating prepared by combining with polyurethane presents a dense lamellar structure, effectively enhancing the mechanical strength and wear resistance of the coating; this dense lamellar structure can effectively prevent air, moisture and corrosive ions from entering the metal surface, reducing the oxidation reaction on the metal surface and effectively enhancing the anti-corrosion performance of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating.

[0025] 2. Excellent corrosion resistance: The high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating prepared by the present invention realizes excellent anti-corrosion effects of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating by inhibiting the transfer of carriers in the metal, enhancing the charge migration resistance, blocking the contact between corrosive ions and the metal, and forming an effective shielding layer on the metal surface; meanwhile, with the high impedance performance of the high-silica zeolite and the synergistic effect with carbon nitride, the migration speed of charges is effectively slowed down, the possibility of metal corrosion is reduced, and at the same time, the barrier protection ability of the metal is increased, further improving the anti-corrosion performance of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating, and its metal anti-corrosion protection efficiency can reach 96.62%.

[0026] 3. Excellent self-healing performance: During actual use, when the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating is damaged by external stimuli, the high-silica zeolite / carbon nitride composite material doped therein will be exposed. Since the high-silica zeolite can enhance the catalytic ability of carbon nitride to 4-6 times that of carbon nitride's own catalytic performance, when the exposed carbon nitride is irradiated by sunlight, it can catalyze the double bonds in the polyurethane to break, thereby liquefying and flowing into the damaged area, and then shielding the light to achieve re-polymerization and filling the damaged area, realizing self-repair, and further improving the anti-corrosion performance and wear resistance of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating. Brief Description of the Drawings

[0027] Figure 1 is the infrared spectrum of the Hβ 25 / CN composite material;

[0028] Figure 2 is the Hβ 25 SEM image of the / CN / PU anti-corrosion coating;

[0029] Figure 3 is the SEM image of the CN / PU coating;

[0030] Figure 4 is the EIS performance diagram of the iron sheet coated with the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating, the pure polyurethane iron sheet, and the pure iron sheet;

[0031] Figure 5 is the Tafel performance diagram of the iron sheet coated with the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating, the pure polyurethane iron sheet, and the pure iron sheet. Detailed Embodiments

[0032] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as a limitation of the present invention.

[0033] Example 1.

[0034] S1: Add 1 g of dicyandiamide and 25 mg of Hβ into 1.5 ml of deionized water, stir for 2 h to make them mix evenly, then dry in an oven at a drying temperature of 55 °C. After the sample is completely dried, transfer it to a crucible and put it into a muffle furnace. Heat the muffle furnace at a heating rate of 5 °C / min to 520 °C and hold for 2 h to calcine the sample to cause a thermal polycondensation reaction; After grinding the composite material generated by calcination, wash it with absolute ethanol and deionized water and dry it to obtain Hβ 25 / CN composite material;

[0035] Such as Figure 1 is the infrared spectrum of the Hβ 25 / CN composite material. It can be seen from the figure that compared with the peak patterns of Hβ and dicyandiamide, the Hβ 25 / CN composite material has a peak position shift in the range of 1000 - 1200 cm -1 This is because after the carbon nitride is combined with Hβ, the electron cloud distribution of the carbon nitride will affect the electron environment around the silicon-oxygen bond in Hβ, changing the vibration frequency of the Si-O-Si bond, thus causing the peak position to shift; In the range of 1200 - 1600 cm -1 There is a peak position shift in the region. This is because the interaction during the combination of Hβ and dicyandiamide (such as hydrogen bond interaction, π-π stacking interaction, etc.) changes the electron environment, and then changes the force constant of the C-N bond, resulting in a change in the absorption peak position. It can be seen from this that Hβ 25 / CN has all the characteristic peaks of carbon nitride and Hβ, proving that the Hβ 25 / CN composite material is successfully synthesized.

[0036] S2: Mix the Hβ 25 / CN composite material and PU in a mass ratio of 1:100, ultrasonicate the mixture for 30 min, and then mechanically stir for 6 h to obtain the Hβ 25 / CN / PU anticorrosive coating.

[0037] Such as Figure 2 is the SEM image of the Hβ 25 / CN / PU anticorrosive coating. It can be seen from the figure that the surface of the Hβ 25 / CN / PU material presents an irregular agglomerated structure. Among them, the high-silica zeolite presents a relatively regular hexahedral morphology and is evenly distributed in the Hβ 25 / CN / PU material. At the same time, the surface of the composite material presents a dense porous structure, and these pores are intertwined with the high-silica zeolite particles.

[0038] Example 2.

[0039] S1: Add 1 g of dicyandiamide and 50 mg of Hβ to 1.5 ml of deionized water, stir for 2 h to mix evenly, then dry in an oven at a drying temperature of 55 °C. After the sample is completely dried, transfer it to a crucible and place it in a muffle furnace. Heat the muffle furnace at a heating rate of 5 °C / min to 520 °C and hold for 2 h to calcine the sample to cause a thermal polycondensation reaction. After grinding the calcined composite material, wash it with absolute ethanol and deionized water and dry it to obtain the Hβ 50 / CN composite material;

[0040] S2: Mix the Hβ 50 / CN composite material and PU in a mass ratio of 1:100, sonicate the mixture for 30 min, and then mechanically stir for 6 h to obtain the Hβ 50 / CN / PU anticorrosive coating.

[0041] Example 3.

[0042] S1: Add 1 g of dicyandiamide and 100 mg of Hβ to 1.5 ml of deionized water, stir for 2 h to mix evenly, then dry in an oven at a drying temperature of 55 °C. After the sample is completely dried, transfer it to a crucible and place it in a muffle furnace. Heat the muffle furnace at a heating rate of 5 °C / min to 520 °C and hold for 2 h to calcine the sample to cause a thermal polycondensation reaction. After grinding the calcined composite material, wash it with absolute ethanol and deionized water and dry it to obtain the Hβ 100 / CN composite material; S2: Mix the Hβ 100 / CN composite material and PU in a mass ratio of 1:100, sonicate the mixture for 30 min, and then mechanically stir for 6 h to obtain the Hβ 100 / CN / PU anticorrosive coating.

[0043] Comparative Example 1:

[0044] The difference between this comparative example and Example 3 is that Hβ is not added, and the remaining preparation methods and conditions are the same as those in Example 3, and the CN / PU coating is prepared. As Figure 3 is the SEM image of the CN / PU coating. It can be seen from the figure that the CN / PU material mainly presents a blocky stacked structure, with a monotonous morphology and few pore structures, further proving that adding high-silica zeolite successfully introduces a pore structure and effectively improves the dispersion of carbon nitride.

[0045] EIS performance test:

[0046] The Hβ 25 / CN / PU anticorrosive coatings, Hβ 50 / CN / PU Anticorrosive Coating and Hβ 100 The / CN / PU anticorrosive coating was applied to a pure iron sheet to prepare an anticorrosive coating. The iron sheets coated with pure polyurethane coating and pure iron sheets were used as control groups for EIS performance testing. As Figure 1 Figure 137 shows the EIS performance diagrams of the iron sheets coated with high-silica zeolite / carbon nitride / polyurethane anticorrosive coating, pure polyurethane coating, and pure iron sheets. By comparing the inner arc radii shown in the EIS diagrams, it was found that the inner arc radius in the EIS diagram of the pure iron sheet was very small, indicating that corrosion ions and charges could be effectively transported in the iron sheet, which was the main cause of metal corrosion. However, the inner arc radius in the EIS diagram of the iron sheet coated with polyurethane increased, indicating that polyurethane had a certain resistance to the migration of corrosion ions and charges, inhibited the generation of corrosion current, and thus slowed down the occurrence of metal corrosion. The EIS diagrams of the iron sheets coated with high-silica zeolite / carbon nitride / polyurethane anticorrosive coating showed varying degrees of enhancement. Among them, Hβ 25 The inner arc radius in the EIS diagram of the / CN / PU anticorrosive coating was the largest, indicating that the high-silica zeolite / carbon nitride / polyurethane anticorrosive coating achieved excellent anticorrosive effects by inhibiting the transfer of carriers in the metal, enhancing the charge migration resistance, blocking the contact between corrosion ions and the metal, and forming an effective shielding layer on the metal surface.

[0047] Tafel Performance Testing:

[0048] The Hβ 25 / CN / PU anticorrosive coatings, Hβ 50 / CN / PU anticorrosive coatings, and Hβ 100 / CN / PU anticorrosive coatings prepared in Examples 1-3 were applied to pure iron sheets to prepare anticorrosive coatings. The iron sheets coated with pure polyurethane and pure iron sheets were used as control groups for Tafel performance testing. Among them, the scanning rate was set at 0.01 V / s, and the potential range was set between the open-circuit potential plus or minus 0.5 V. As Figure 2 Figure 142 shows the Tafel performance diagrams of the iron sheets coated with high-silica zeolite / carbon nitride / polyurethane anticorrosive coating, pure polyurethane, and pure iron sheets. The following table shows the Tafel fitting data of the iron sheets coated with high-silica zeolite / carbon nitride / polyurethane anticorrosive coating, pure polyurethane, and pure iron sheets. Combining the Tafel performance diagrams and the Tafel fitting data in the table, the metal anticorrosion protection efficiency calculated according to the following formula was greater than 90%. The corrosion potentials of the Hβ 25 / CN / PU anticorrosive coating, Hβ 50 / CN / PU anticorrosive coating, and Hβ 100 / CN / PU anticorrosive coating were -0.59 V, -0.66 V, and -0.71 V, respectively. This was mainly because high-silica zeolite / carbon nitride had a strong charge blocking effect, hindered charge migration, further blocked the occurrence of corrosion, and enhanced the corrosion resistance of the high-silica zeolite / carbon nitride / polyurethane anticorrosive coating.

[0049]

[0050] wherein, i corr,0 is the corrosion current density of the uncoated paint, and i corr,i is the corrosion current density after applying various coatings.

[0051]

[0052] In summary, in the present invention, a high-silica zeolite / carbon nitride composite material is synthesized by an in-situ thermal polycondensation method using high-silica zeolite and dicyandiamide, and filled into waterborne polyurethane to obtain a high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating. By inhibiting the transfer of carriers in the metal, enhancing the charge migration resistance, blocking the contact between corrosive ions and the metal, and forming an effective shielding layer on the metal surface, the excellent anti-corrosion effect of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating is achieved; at the same time, by virtue of the high impedance performance of the high-silica zeolite and the synergistic effect with carbon nitride, the migration speed of charges is effectively slowed down, the possibility of metal corrosion is reduced, and the barrier protection ability of the metal is increased, further improving the anti-corrosion performance of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating.

[0053] It can be understood that the present invention is described by some embodiments. Those skilled in the art know that, without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating, characterized in that, By mass parts, it is composed of the following components in mass parts: 1 part of high-silica zeolite / carbon nitride composite material and 100 parts of polyurethane; The high-silica zeolite / carbon nitride composite material is obtained by adding dicyandiamide and high-silica zeolite into deionized water, stirring evenly, drying, calcining at 520 °C for 2 h, grinding, and then washing and drying with absolute ethanol and deionized water; the mass ratio of the high-silica zeolite to carbon nitride is 10-50:1; the high-silica zeolite is hydrogen-type β zeolite.

2. A preparation method of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating according to claim 1, characterized in that, It includes the following steps: S1: Add dicyandiamide and high-silica zeolite into deionized water, stir evenly, then dry in an oven. After the sample is completely dry, transfer it to a crucible and put it into a muffle furnace. Heat up the muffle furnace and calcine the sample; grind the calcined product and wash and dry it with absolute ethanol and deionized water to obtain a high-silica zeolite / carbon nitride composite material; S2: Mix the high-silica zeolite / carbon nitride composite material with polyurethane, ultrasonicate the mixture, and then carry out mechanical stirring to obtain a high-silica zeolite / carbon nitride / polyurethane anticorrosive coating.

3. The preparation method of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating according to claim 2, wherein In S1, the stirring time is 2-3 h and the rotation speed is 200 ppm.

4. The preparation method of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating according to claim 2, characterized in that, In S1, the drying temperature is 55 °C.

5. The preparation method of the high-silica zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 2, characterized in that, In S1, the heating rate is 5-10 °C / min.

6. The preparation method of the high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating according to claim 2, characterized in that, In S2, the ultrasonication time is 30 min; the mechanical stirring time is 6 h.

7. Use of a high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating as described in claim 1 or a high-silica zeolite / carbon nitride / polyurethane anti-corrosion coating prepared by the preparation method described in any one of claims 2-6, characterized in that, It is applied to the anticorrosion of metal surfaces.

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