High-silicon zeolite / carbon nitride / polyurethane anticorrosive paint as well as preparation method and application thereof

Abstract

The invention discloses a high-silicon zeolite / carbon nitride / polyurethane anticorrosive paint as well as a preparation method and application thereof, relates to the technical field of paints, and solves the problems of poor organic-inorganic component compatibility, poor corrosion resistance and poor wear resistance of the traditional metal anticorrosive paint. According to the invention, high-silicon zeolite and dicyandiamide are subjected to an in-situ thermal polycondensation method to synthesize a high-silicon zeolite / carbon nitride composite material, and waterborne polyurethane is filled with the high-silicon zeolite / carbon nitride / polyurethane composite material to obtain the high-silicon zeolite / carbon nitride / polyurethane anticorrosive paint. By inhibiting transfer of carriers in metal, enhancing charge migration resistance, blocking corrosion ions from making contact with the metal and forming an effective shielding layer on the surface of the metal, excellent corrosion resistance and wear resistance of the high-silicon zeolite / carbon nitride / polyurethane anticorrosive paint are achieved; in addition, after the anti-corrosion coating is damaged due to external stimulation, disulfide bonds in polyurethane can be subjected to reversible fracture-connection under the catalytic action of carbon nitride, and self-repairing is achieved. The method is applied to metal surface corrosion prevention.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a high-silicon zeolite / carbon nitride / polyurethane anticorrosive coating and a preparation method and application thereof. Background Art

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

[0003] Traditional metal anti-corrosion coatings are mainly composed of organic resins. Common organic resins include epoxy resins, polyurethane (PU) resins, etc. These resins can form a solid protective film, effectively isolating the metal from the contact with corrosive factors in the external environment (such as moisture, oxygen, acid and alkali, etc.) to achieve the purpose of corrosion prevention. However, in practical applications, the corrosion resistance of organic resin coatings is often limited by the properties of the organic resins themselves. 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 organic resin coatings. However, the compatibility problem between inorganic fillers and organic resins 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 fillers during the coating process, easy precipitation or shedding, and further reduces the corrosion resistance and wear resistance of the coating. For example, Chinese patent document CN108329797A discloses a graphene water-based coating and a preparation method, which can slow down the reaction rate between magnesium alloy substrate and water, reduce water corrosion to magnesium alloy, and at the same time improve the surface tension of aluminum alloy, increase surface wettability, and play a sealing role on the surface of aluminum alloy, thereby improving the consistency of coating appearance; however, the corrosion resistance and wear resistance of the coating need to be improved. Chinese patent document CN114369746A discloses a high-temperature aluminum alloy for floor heating pipes and its production process, which uses corrosion-resistant coating to treat the surface of aluminum alloy pipe substrate, thereby improving the corrosion resistance and heat resistance of aluminum alloy pipe substrate; and introduces modified graphene to modify the coating, thereby improving the heat dissipation of silicone ceramic coating, but the wear resistance of the coating needs to be improved.

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

[0005] In order to solve the problems of poor compatibility of organic and inorganic components, poor corrosion resistance and wear resistance in traditional metal anti-corrosion coatings, the present invention proposes a high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating and its preparation method and application. The specific technical scheme is as follows: A high-silicon zeolite / carbon nitride / polyurethane anticorrosive coating, comprising the following components in parts by mass: 1 part of high silicon zeolite / carbon nitride composite material, 100 parts of polyurethane; Preferably, it also includes 0.01-1.2 parts of penetrant, 0.01-1 parts of emulsifier, 0-0.05 parts of defoamer, 0-10 parts of film-forming aid, and 0-1 parts of other additives; The high-silicon zeolite / carbon nitride composite material is synthesized from high-silicon zeolite and dicyandiamide by an in-situ thermal polycondensation method; the mass ratio of the high-silicon zeolite to the carbon nitride is 10-50:1, and the high-silicon zeolite is hydrogen-type beta zeolite (Hβ).

[0006] A method for preparing the above-mentioned high-silicon zeolite / carbon nitride / polyurethane anticorrosive coating comprises the following steps: S1: Add dicyandiamide and high-silicon zeolite into deionized water, stir to mix evenly, and then dry in an oven. After the sample is completely dried, transfer it to a crucible and put it into a muffle furnace. Heat the muffle furnace to calcine the sample to cause a thermal polycondensation reaction; grind the calcined composite material, wash it with anhydrous ethanol and deionized water, and dry it to obtain a high-silicon zeolite / carbon nitride composite material; S2: mixing the high-silicon zeolite / carbon nitride composite material with polyurethane, subjecting the mixture to ultrasonic treatment, and then subjecting the mixture to mechanical stirring to obtain a high-silicon zeolite / carbon nitride / polyurethane anticorrosive coating; Furthermore, the carbon nitride is calcined from a precursor dicyandiamide, wherein the dicyandiamide is analytically pure and does not need to be further purified; the high-silica zeolite is experimentally pure and does not need to be further purified; Furthermore, the stirring time in S1 is 2 to 3 h, and the rotation speed is 200 ppm; Further, the drying temperature in S1 is 55°C; Furthermore, the heating rate in S1 is 5-10°C / min; Further, the calcination temperature in S1 is 520°C; Further, the calcination time in S1 is 2 h; Furthermore, the mass ratio of the high silicon zeolite / carbon nitride composite material to the polyurethane in the S2 is 1:100; Furthermore, the ultrasonic time in S2 is 30 min; Furthermore, the mechanical stirring time in S2 is 6 h.

[0007] An application of the high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating is applied to metal surface anti-corrosion.

[0008] Compared with the prior art, the present invention solves the problems of poor compatibility of organic and inorganic components, poor corrosion resistance and wear resistance in traditional metal anticorrosion coatings, and has the following specific beneficial effects: 1. Excellent structural stability: The present invention synthesizes a high-silicon zeolite / carbon nitride composite material by in-situ thermal polycondensation of high-silicon zeolite and dicyandiamide, and fills the composite material into waterborne polyurethane to obtain a high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating. First, the introduction of high-silicon zeolite improves the catalytic activity of carbon nitride, and also enhances the structural stability of the anti-corrosion coating through the synergistic effect with carbon nitride; at the same time, the high surface area and pore structure of high-silicon zeolite effectively improve the dispersibility of carbon nitride, avoiding its aggregation in the polyurethane matrix, thereby ensuring the uniform distribution of the high-silicon zeolite / carbon nitride composite material in the anti-corrosion coating, enhancing its compatibility, and thereby enhancing the mechanical strength, wear resistance and flexibility of the anti-corrosion coating; secondly, carbon nitride itself has a flaky structure, and the high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating prepared in combination with polyurethane presents a dense lamellar structure, which effectively enhances 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, reduce the oxidation reaction on the metal surface, and effectively enhance the anti-corrosion performance of the high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating.

[0009] 2. Excellent anti-corrosion performance: The high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating prepared by the present invention achieves excellent anti-corrosion effect 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; at the same time, by virtue of the high impedance performance of high-silicon zeolite and the synergistic effect between it and carbon nitride, the migration speed of the charge is effectively slowed down, the possibility of metal corrosion is reduced, and the barrier protection ability of the metal is increased, thereby further improving the anti-corrosion performance of the high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating, and its metal anti-corrosion protection efficiency can reach 96.62%.

[0010] 3. Excellent self-healing performance: In actual use, the high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating is damaged by external stimuli, which will cause the high-silicon zeolite / carbon nitride composite material doped therein to be exposed. Since high-silicon zeolite can enhance the catalytic ability of carbon nitride to 4 to 6 times the catalytic performance of carbon nitride itself, when the exposed carbon nitride is exposed to sunlight, it can catalyze the breaking of double bonds in polyurethane, thereby liquefying and flowing into the damaged area, and then shielding the light to achieve re-polymerization and fill the damaged area, achieving self-repair, and further improving the anti-corrosion performance and wear resistance of the high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Hβ 25 Infrared spectra of / CN composites; Figure 2 Hβ 25 / SEM image of CN / PU anti-corrosion coating; Figure 3 This is the SEM image of CN / PU coating; Figure 4 EIS performance diagram of iron sheet coated with high silicon zeolite / carbon nitride / polyurethane anti-corrosion coating, pure polyurethane and pure iron sheet; Figure 5 Tafel performance diagram of iron sheet coated with high silicon zeolite / carbon nitride / polyurethane anti-corrosion coating, pure polyurethane and pure iron sheet. DETAILED DESCRIPTION

[0012] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as a limitation to the present invention.

[0013] Example 1. S1: 1 g of dicyandiamide and 25 mg of Hβ were added to 1.5 ml of deionized water, stirred for 2 h to mix evenly, and then dried in an oven at a drying temperature of 55 °C. After the sample was completely dried, it was transferred to a crucible and placed in a muffle furnace. The temperature of the muffle furnace was raised to 520 °C at a heating rate of 5 °C / min and then kept at this temperature for 2 h. The sample was calcined to cause a thermal polycondensation reaction. The calcined composite material was ground, washed with anhydrous ethanol and deionized water, and dried to obtain Hβ 25 / CN composite materials; like Figure 1 Hβ 25 The infrared spectrum of the / CN composite material shows that compared with the peaks of Hβ and dicyandiamide, Hβ 25 / CN composite materials at 1000~1200 cm -1 The peak position of the region moves. This is because after carbon nitride is combined with Hβ, the electron cloud distribution of carbon nitride will affect the electronic environment around the silicon-oxygen bond in Hβ, changing the vibration frequency of the Si-O-Si bond, thus moving the peak position; at 1200~1600 cm -1 The peak position of the region moves. This is because the interaction between Hβ and dicyandiamide (such as hydrogen bonding, π-π stacking, etc.) changes the electronic environment, thereby changing the force constant of the CN bond, causing the absorption peak position to change. 25 / CN has all the characteristic peaks of carbon nitride and Hβ, proving that Hβ 25 / CN composite materials were successfully synthesized.

[0014] S2: Place Hβ 25 The / CN composite material was mixed with PU at a mass ratio of 1:100, and the mixture was subjected to ultrasound for 30 min and then mechanically stirred for 6 h to obtain Hβ 25 / CN / PU anti-corrosion coating.

[0015] like Figure 2 Hβ 25 / CN / PU anti-corrosion coating SEM picture, from which we can see that Hβ 25 The surface of the / CN / PU material presents an irregular agglomerate structure, among which the high-silicon zeolite presents a relatively regular hexahedral morphology. 25 / CN / PU material is evenly distributed, and the surface of the composite material presents a dense porous structure, and these pores are intertwined with high-silicon zeolite particles.

[0016] Example 2. S1: 1 g of dicyandiamide and 50 mg of Hβ were added to 1.5 ml of deionized water, stirred for 2 h to mix evenly, and then dried in an oven at a drying temperature of 55 °C. After the sample was completely dried, it was transferred to a crucible and placed in a muffle furnace. The temperature of the muffle furnace was raised to 520 °C at a heating rate of 5 °C / min and then kept at this temperature for 2 h. The sample was calcined to cause a thermal polycondensation reaction. The calcined composite material was ground, washed with anhydrous ethanol and deionized water, and dried to obtain Hβ 50 / CN composite materials; S2: Place Hβ 50 The / CN composite material was mixed with PU at a mass ratio of 1:100, and the mixture was subjected to ultrasound for 30 min and then mechanically stirred for 6 h to obtain Hβ 50 / CN / PU anti-corrosion coating.

[0017] Example 3. S1: 1 g of dicyandiamide and 100 mg of Hβ were added to 1.5 ml of deionized water, stirred for 2 h to mix evenly, and then dried in an oven at a drying temperature of 55 °C. After the sample was completely dried, it was transferred to a crucible and placed in a muffle furnace. The temperature of the muffle furnace was raised to 520 °C at a heating rate of 5 °C / min and then kept at this temperature for 2 h. The sample was calcined to cause a thermal polycondensation reaction. The calcined composite material was ground, washed with anhydrous ethanol and deionized water, and dried to obtain Hβ 100 / CN composite material; S2: Hβ 100 The Hβ / CN composite material was mixed with PU at a mass ratio of 1:100, and the mixture was subjected to ultrasound for 30 min and then mechanically stirred for 6 h to obtain 100 / CN / PU anti-corrosion coating.

[0018] Comparative Example 1: The difference between this comparative example and Example 3 is that Hβ is not added, and the rest of the preparation method and conditions are the same as those of Example 3 to prepare a CN / PU coating. Figure 3 This is the SEM image of the CN / PU coating. It can be seen from the figure that the CN / PU material mainly presents a block stacking structure with a monotonous morphology and a sparse porous structure, which further proves that the addition of high-silicon zeolite successfully introduced a pore structure and effectively improved the dispersibility of carbon nitride.

[0019] EIS performance test: The Hβ prepared in Example 1-3 25 / CN / PU anti-corrosion coating, Hβ 50 / CN / PU anti-corrosion coating and Hβ 100 The / CN / PU anti-corrosion coating was applied on pure iron sheets to prepare anti-corrosion coatings, and the iron sheets coated with pure polyurethane coatings and pure iron sheets were used as control groups for EIS performance tests. Figure 1 These are the EIS performance graphs of iron sheets coated with high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coatings, pure polyurethane coatings, and pure iron sheets. By comparing the inner arc radius shown in the EIS graph, it was found that the inner arc radius in the EIS graph of the pure iron sheet was very small, which indicates that the corrosion ions and charges can be effectively transmitted in the iron sheet, which is the main cause of metal corrosion. However, the inner arc radius in the EIS graph of the iron sheet coated with polyurethane becomes larger, which indicates that polyurethane has a certain resistance to the migration of corrosion ions and charges, inhibiting the generation of corrosion current, thereby slowing down the occurrence of metal corrosion. The EIS graphs of the iron sheets coated with high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coatings show different degrees of enhancement, among which Hβ 25The inner arc radius in the EIS diagram of the / CN / PU anti-corrosion coating is the largest, which indicates that the high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating achieves excellent anti-corrosion effect by inhibiting the transfer of carriers within 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.

[0020] Tafel performance test: The Hβ prepared in Example 1-3 25 / CN / PU anti-corrosion coating, Hβ 50 / CN / PU anti-corrosion coating and Hβ 100 The anti-corrosion coating was prepared by brushing the / CN / PU anti-corrosion coating on the pure iron sheet, and the iron sheet coated with pure polyurethane and the pure iron sheet were used as the control group for Tafel performance test, in which the scanning rate was set to 0.01 V / s and the potential range was set to the open circuit potential plus or minus 0.5 V. Figure 2 The following table shows the Tafel performance diagram of iron sheets coated with high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating, pure polyurethane, and pure iron sheets. The following table shows the Tafel fitting data of iron sheets coated with high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating, pure polyurethane, and pure iron sheets. Combining the Tafel performance diagram and the Tafel fitting data in the table, the metal anti-corrosion protection efficiency is calculated according to the following formula to be greater than 90%, Hβ 25 / CN / PU anti-corrosion coating, Hβ 50 / CN / PU anti-corrosion coating and Hβ 100 The corrosion potentials of the / CN / PU anti-corrosion coatings are -0.59V, -0.66V and -0.71V, respectively. This is mainly because high-silicon zeolite / carbon nitride has a strong charge blocking effect, which hinders charge migration, further blocks the occurrence of corrosion, and enhances the corrosion resistance of high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coatings.

[0021]

[0022] In the formula, i corr,0 is the corrosion current density without coating, i corr,i Corrosion current density after applying various coatings.

[0023]

[0024] In summary, the present invention synthesizes a high-silicon zeolite / carbon nitride composite material by in-situ thermal polycondensation of high-silicon zeolite and dicyandiamide, and fills it into waterborne polyurethane to obtain a high-silicon 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 high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating achieves an excellent anti-corrosion effect; at the same time, by virtue of the high impedance performance of high-silicon zeolite and the synergistic effect with carbon nitride, the migration speed of the charge 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-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating.

[0025] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances 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 are within the scope of protection of the present invention.

Claims

1. A high silicon zeolite / carbon nitride / polyurethane anticorrosion coating, characterized in that: By weight, it contains the following components: 1 part of high silicon zeolite / carbon nitride composite material, 100 parts of polyurethane; The high-silicon zeolite / carbon nitride composite material is synthesized from high-silicon zeolite and dicyandiamide by an in-situ thermal polycondensation method, and the high-silicon zeolite is a hydrogen-type beta zeolite.

2. The high silicon zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 1, characterized in that: The mass ratio of the high silicon zeolite to carbon nitride is 10-50:

1.

3. A method for preparing the high silicon zeolite / carbon nitride / polyurethane anticorrosive coating as claimed in claim 1 or 2, characterized in that: The following steps are involved: S1: Add dicyandiamide and high-silicon zeolite to deionized water, stir evenly, and then dry in an oven. After the sample is completely dried, transfer it to a crucible and put it into a muffle furnace. Heat the muffle furnace to calcine the sample; grind the calcined product, wash it with anhydrous ethanol and deionized water, and dry it to obtain a high-silicon zeolite / carbon nitride composite material; S2: Mix the high-silicon zeolite / carbon nitride composite material with polyurethane, perform ultrasound on the mixture, and then perform mechanical stirring to obtain a high-silicon zeolite / carbon nitride / polyurethane anti-corrosion coating.

4. The method for preparing the high silicon zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 3, characterized in that: The stirring time in S1 is 2-3 h, and the rotation speed is 200 ppm.

5. The method for preparing the high silicon zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 3, characterized in that: The drying temperature in S1 is 55°C.

6. The method for preparing the high silicon zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 3, characterized in that: The heating rate in S1 is 5-10°C / min.

7. The method for preparing the high silicon zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 3, characterized in that: The calcination temperature in S1 is 520°C.

8. The method for preparing the high silicon zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 3, characterized in that: The calcination time in S1 is 2 h.

9. The method for preparing the high silicon zeolite / carbon nitride / polyurethane anticorrosive coating according to claim 3, characterized in that: The ultrasonic time in S2 is 30 min; and the mechanical stirring time is 6 h.

10. An application of the high silicon zeolite / carbon nitride / polyurethane anticorrosion coating according to claim 1 or 2 or the high silicon zeolite / carbon nitride / polyurethane anticorrosion coating prepared by the preparation method of any one of claims 3 to 9, characterized in that: Used for corrosion protection of metal surfaces.

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