A sodium alginate / urushiol-based aqueous coating modifier

Abstract

The application discloses a sodium alginate / urushiol-based water-based paint modifier, which is prepared by the following steps: firstly, pre-supporting treatment of alpha-zirconium phosphate is carried out by using cetyltrimethylammonium bromide, and in-situ reduction of the alpha-zirconium phosphate is carried out to generate urushiol titanium, so as to obtain a urushiol-based corrosion inhibitor; simultaneously, grafting of sodium alginate is carried out by using dodecyl triethoxysilane, so as to obtain amphiphilic sodium alginate; then, the obtained urushiol-based corrosion inhibitor and the obtained amphiphilic sodium alginate are stirred and uniformly mixed in deionized water, and the water-based paint modifier is prepared by ball milling. The prepared water-based paint modifier has good hydrophilicity and corrosion inhibition effect, and when the water-based paint modifier is used in water-based paint, the long-term corrosion resistance of the water-based paint to a metal substrate can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of marine corrosion protection, specifically relating to a sodium alginate / urushiol-based waterborne coating modifier and its preparation method. Background Technology

[0002] Water-based coatings, as the most important type of environmentally friendly coating, have become one of the development directions of the coating industry due to their energy-saving and environmentally friendly characteristics. Currently, there is relatively little research on water-based coatings in China, and only a small number of water-based coatings are applied, while water-based coating production lines already exist in Europe. Therefore, research on environmentally friendly water-based coatings will attract widespread attention in the future.

[0003] Waterborne polyurethane (WPU) coatings, using water as a solvent, possess advantages such as high strength, low-temperature fatigue resistance, environmental friendliness, good compatibility, and ease of modification. They are widely applicable in fields such as biomedicine, chemical industry, building materials, and aerospace, aligning with green production and low-carbon environmental protection goals. However, the following problems still exist: First, the raw material cost is relatively high, resulting in low cost-effectiveness and limited application range; second, using water as a solvent requires the introduction of hydrophilic ionic groups, leading to slow film formation and poor water resistance; third, the anti-corrosion performance is generally poor, necessitating modification to broaden the application range. Summary of the Invention

[0004] This invention addresses the problem of insufficient corrosion resistance of water-based coatings in marine environments by providing a sodium alginate / urushiol-based water-based coating modifier. The coating prepared by this invention not only creates a labyrinth effect due to the barrier effect of the two-dimensional material, extending the corrosion path, but also improves the stability of the oil-water two-phase system through the dispersing effect of APSA. This allows the urushiol-based corrosion inhibitor to be fully dispersed in the water-based coating, resulting in a synergistic corrosion protection effect between the two-dimensional material and UTi. Therefore, compared with the original water-based coating, its corrosion resistance can be improved by 1-2 orders of magnitude.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A sodium alginate / urushiol-based waterborne coating modifier is prepared by first pre-supporting zirconium phosphate (ZrP) with hexadecyltrimethylammonium bromide (CTAB), followed by in-situ reduction of zirconium phosphate in the interlayer to generate urushiol titanium (UTi), thus obtaining an urushiol-based corrosion inhibitor (UTPCZrP). Then, sodium alginate (SA) is grafted with dodecyltriethoxysilane (DTES) to prepare amphiphilic sodium alginate (APSA). Finally, the prepared urushiol-based corrosion inhibitor and amphiphilic sodium alginate are thoroughly mixed to obtain the waterborne coating modifier. The specific operation is as follows:

[0007] 1) Preparation of urushiol-based corrosion inhibitor: Zirconium α-phosphate was ultrasonically dispersed in water, then hexadecyltrimethylammonium bromide was added, and the mixture was ultrasonically treated for 1 h. After centrifugation, washing, and drying, the intercalation product was obtained. The intercalation product was then vigorously stirred and mixed with tetrabutyl titanate in xylene. A xylene solution of urushiol was then added dropwise, and the temperature was raised to 80 °C and kept at that temperature for 1 h. The temperature was then raised to 120 °C and kept at that temperature for 2 h. Finally, the temperature was raised to 138 °C and kept at that temperature for 1 h to obtain the urushiol-based corrosion inhibitor.

[0008] 2) Preparation of amphiphilic sodium alginate: Sodium alginate was dissolved in an ethanol solution, and the pH was adjusted to 9±0.3 by adding ammonia. Dodecyltriethoxysilane was added dropwise, and the reaction was carried out at room temperature for 24 h. The product was washed with ethanol and dried to obtain amphiphilic sodium alginate.

[0009] 3) Preparation of modifier: The prepared urushiol-based corrosion inhibitor, amphiphilic sodium alginate and deionized water are stirred and mixed in proportion, and then ball milled in a ball mill to obtain the water-based coating modifier.

[0010] Furthermore, the mass ratio of hexadecyltrimethylammonium bromide to zirconium α-phosphate used in step 1) is 3.22:1.

[0011] Furthermore, the mass ratio of the intercalation product, tetrabutyl titanate, and urushiol used in step 1) is 3:4:7.44.

[0012] Further, in step 2), the volume ratio of ethanol to water in the ethanol solution is 9:1.

[0013] Furthermore, in step 2), the ratio of sodium alginate to dodecyltriethoxysilane is 3g:2mL.

[0014] Furthermore, in step 3), the mass ratio of urushiol-based corrosion inhibitor, amphiphilic sodium alginate, and deionized water is 1:1:25.

[0015] The sodium alginate / urushiol-based waterborne coating modifier obtained above can be added to waterborne coatings to prepare modified waterborne coatings with long-lasting anti-corrosion properties for metal substrates in marine environments.

[0016] Furthermore, the amount of sodium alginate / urushiol-based waterborne coating modifier added to the waterborne coating is 5 wt%.

[0017] Furthermore, the waterborne coating includes any one or more of waterborne polyurethane (WPU), waterborne epoxy resin (WEP), waterborne polyester (WPE), and waterborne silicone resin (WSR).

[0018] This invention pre-supports ZrP, initially expanding the interlayer spacing. Then, utilizing the ion exchange and intercalation properties of ZrP, UTi is reduced in situ between ZrP layers (the process of in-situ reduction of UTi between layers requires controlling the flowability of the final product by evaporating the solvent, so that it reaches a certain viscosity to be the final product). The heat generated by in-situ polymerization overcomes the Coulomb forces between layers, making the layers easier to exfoliate and preventing the aggregation of nanosheets, ultimately obtaining UTPCZrP. UTPCZrP is then added to the obtained APSA to obtain a modifier that can be efficiently dispersed in water-based coatings.

[0019] The modified waterborne coating prepared using the sodium alginate / urushiol-based waterborne coating modifier of this invention has improved smoothness, thermal stability, and resistance to liquid media corrosion. It not only maintains the good physical and mechanical properties of waterborne coatings, but also significantly improves the corrosion resistance of waterborne coatings in marine environments, and can be used for the protection of metal substrates.

[0020] The sodium alginate / urushiol-based waterborne coating modifier prepared in this invention has the following excellent effects:

[0021] 1. It avoids the problem of two-dimensional material agglomeration. By utilizing the ion exchange and intercalation properties of ZrP, UTi is reduced in situ between ZrP layers. The heat generated by in-situ polymerization overcomes the Coulomb forces between the layers, making it easier to peel off the layers and preventing the agglomeration of nanosheets, ultimately obtaining UTPCZrP.

[0022] 2. Excellent synergistic anti-corrosion performance. Both UTi and ZrP can play a barrier role, preventing corrosive media from entering the matrix resin. At the same time, the lamellar material can also generate a complex labyrinth effect, prolonging the penetration path of corrosive media.

[0023] 3. Outstanding dispersant performance. Grafted SA disperses better in both oil and water phases, enabling the modifier to achieve a highly efficient and stable state and be uniformly dispersed in water-based coatings. This effectively solves the problem of poor dispersibility of traditional phenolic materials in water-based resins. Furthermore, the increased density of the two-dimensional material in the water-based coating reduces the generation of internal defects in the coating, avoids localized microgalvanic corrosion, and further improves the long-term corrosion resistance of the coating.

[0024] In summary, this invention solves the problem that traditional water-based coatings have poor anti-corrosion performance due to their inherent defects, and cannot achieve long-term anti-corrosion in high-salinity environments such as the ocean. It improves the long-term anti-corrosion capability of water-based coatings for metal substrates under extreme conditions, and fills the gap in current research on the modification of water-based coatings and the combined utilization of urushiol and water-based coatings. Attached Figure Description

[0025] Figure 1 Comparison of infrared spectra of ZrP, urushiol, UTi and CZrP and UTPCZrP prepared in Example 1.

[0026] Figure 2 XRD comparison diagrams of ZrP and CZrP and UTPCZrP prepared in Example 1.

[0027] Figure 3 The image shows the EDS-Mapping diagram of the UTPCZrP prepared in Example 1.

[0028] Figure 4 SEM comparison images of ZrP with CZrP and UTPCZrP prepared in Example 1.

[0029] Figure 5 The image shows an IR comparison between SA and APSA prepared in Example 1.

[0030] Figure 6 A graph showing the comparison of suspensions with and without APSA after different number of days.

[0031] Figure 7 Comparison of the microstructure of WPU coatings prepared with different amounts of AUZ.

[0032] Figure 8 Comparison of Tafel polarization curves for WPU coatings prepared with different amounts of AUZ.

[0033] Figure 9 Electrochemical impedance spectroscopy (EIC) analysis of WPU coatings prepared with different amounts of AUZ after immersion in 3.5 wt% NaCl for different numbers of days.

[0034] Figure 10 Comparison of the anti-corrosion effects of modified coatings prepared with only CTAB and APSA, and without either.

[0035] Figure 11 The image shows a comparison of the Tafel polarization curves of the modified waterborne coatings obtained in Examples 2-4.

[0036] Figure 12 Electrochemical impedance spectroscopy (EIS) diagrams are shown for the modified waterborne coatings obtained in Examples 2-4 after immersion in a 3.5 wt% NaCl environment for different numbers of days. Detailed Implementation

[0037] A sodium alginate / urushiol-based waterborne coating modifier, the preparation steps of which are as follows:

[0038] 1) Zirconium α-phosphate (ZrP) was ultrasonically dispersed in water, then hexadecyltrimethylammonium bromide (CTAB) was added, and the mixture was ultrasonically treated for 1 hour. After centrifugation, washing, and drying, the intercalation product was obtained. The mass ratio of hexadecyltrimethylammonium bromide to zirconium α-phosphate used was 3.22:1.

[0039] 2) The obtained intercalation product and tetrabutyl titanate were vigorously mixed in xylene, and then a xylene solution of urushiol was added dropwise. The temperature was raised to 80°C and the reaction was maintained for 1 hour. Then the temperature was raised to 120°C and the reaction was maintained for 2 hours. Finally, the temperature was raised to 138°C and the reaction was maintained for 1 hour to obtain urushiol-based corrosion inhibitor (UTPCZrP). The mass ratio of the intercalation product, tetrabutyl titanate and urushiol used was 3:4:7.44.

[0040] 3) Sodium alginate (SA) was dissolved in a mixed solution of ethanol and water (9:1, v / v), and the pH was adjusted to 9±0.3 with ammonia. Dodecyltriethoxysilane (DTES) was then added dropwise, and the mixture was reacted at room temperature for 24 h. The product was washed with ethanol and dried to obtain amphiphilic sodium alginate (APSA). The ratio of sodium alginate to dodecyltriethoxysilane used was 3 g: 2 mL.

[0041] 4) The prepared UTPCZrP, APSA and deionized water are mixed at a mass ratio of 1:1:25 and then ball-milled in a ball mill to obtain the water-based coating modifier.

[0042] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0043] In the examples, the adhesion test was conducted in accordance with national standard GB / T5210-2006; the impact resistance test was conducted in accordance with national standard GB / T1732-1993; the flexibility test was conducted in accordance with national standard GB / T6742-2007; and the pencil hardness test was conducted in accordance with national standard GB / T 6739-2006.

[0044] The preparation of pure urushiol titanium was carried out by thoroughly mixing 50 g of urushiol and 50 g of xylene at 138 °C and then refluxing to dehydrate for 1 h. The temperature was then lowered to 70 °C, and a mixed solution of 3 g tetrabutyl titanate and 30 g xylene was added dropwise. After reacting uniformly for 40 min, 3 g of sodium carbonate was added, and the temperature was raised to 120 °C and reacted for 1 h to obtain UTi.

[0045] Example 1

[0046] (1) Weigh 1 g of ZrP and disperse it in 300 mL of distilled water. Sonicate for a certain time until the dispersion is uniform. Then add 3.22 g of CTAB to the above dispersion and sonicate for 1 h. Centrifuge and wash the obtained product three times with ethanol. Then vacuum dry overnight. The intercalated compound is denoted as CZrP.

[0047] (2) Take 3 g of CZrP obtained in step (1), add 4 g of tetrabutyl titanate and 6 g of xylene into a 250 mL three-necked round-bottom flask, set up the reaction apparatus, and install a thermometer, a dropping funnel and a reflux condenser in the three necks respectively. Stir the mixture vigorously at room temperature until homogeneous, then add a solution prepared by 7.44 g of xylene and 7.44 g of urushiol dropwise, while gradually heating the system to 80 °C and reacting for 1 h. Then gradually heat the system to 120 °C and react for 2 h, and then heat it to 138 °C and react for 1 h. The product is named UTPCZrP.

[0048] (3) Measure 3 g of SA and add it to a mixture of ethanol and deionized water in a volume ratio of 9:1. Stir evenly at room temperature, and adjust the pH value to 9.0±0.3 with ammonia water. Then add 2 mL of DTES dropwise using a dropper. React at room temperature for 24 h. Wash the product three times with ethanol and vacuum dry overnight. The obtained product is called APSA.

[0049] (4) Add the UTPCZrP obtained in step (2), the APSA obtained in step (3), and deionized water into a beaker at a ratio of 1g:1g:25mL and stir evenly. Then place the mixture in a ball mill and ball mill it. The resulting product is denoted as AUZ.

[0050] (5) Add 5 wt% AUZ to waterborne polyurethane (WPU) and stir evenly to obtain modified waterborne coating.

[0051] The modified water-based coating prepared in this embodiment has an adhesion grade of 0, an impact resistance distance of 80cm, a flexibility of 0.5mm, and a pencil hardness of 6H.

[0052] A comparison of the infrared spectra of ZrP, urushiol, UTi, and the prepared CZrP and UTPCZrP is shown in the figure. Figure 1 .Depend on Figure 1 It can be seen that, compared to ZrP, CZrP has a higher growth rate at 2920 cm⁻¹. -1 and 2848 cm -1 The presence of distinct stretching vibration absorption peaks for -CH3 and -CH2- in the vicinity is attributed to the functional groups introduced by CTAB. Similarly, due to the hydrogen bonding between -NH2 and P-OH, PO4 exhibits a peak at 1017 cm⁻¹. -1 and 958 cm -1The absorption bands shifted to 1021 cm⁻¹. -1 and 964 cm -1 This confirms the successful introduction of CTAB. And 3600-3200, 3010, 2923, 2852, 982 and 945 cm -1 The absorption peak at 3200-3600 cm⁻¹ is a characteristic peak of urushiol, UTi, and UTPZrP. -1 The broad peak at [value missing] is attributed to the -OH stretching vibration on the urushiol benzene ring. It can be seen that the hydroxyl content decreases due to the chelation reaction between the hydroxyl group and titanium ions, resulting in a weakening of the UTPCZrP peak. [Values ​​missing] are located at 982 and 945 cm⁻¹. -1 The bands at that location are attributed to the triene bonds (-C=CC=CC=C-) on the side chains of the benzene ring. Due to the opening of the double bonds and polymerization, the triene bonds in UTi and UTPCZrP disappear. These results demonstrate the formation of urushiol titanium polymers.

[0053] XRD comparison images of ZrP with prepared CZrP and UTPCZrP are shown below. Figure 2 As shown in the figure, ZrP exhibits good crystallinity, with three typical peaks appearing at 2θ = 11.8°, 19.9°, and 25.1°, corresponding to the diffraction peaks of the (002), (110), and (112) planes of ZrP, respectively. The interlayer spacing of its (002) diffraction peak is 0.76 nm (calculated according to the Bragg equation 2dsinθ = nλ). After CTAB pretreatment, its (002) diffraction peak shifts to a 2θ value of 4.7°, with a corresponding interlayer spacing of 1.90 nm. A weak peak still exists at a 2θ value of 11.8°, indicating that ZrP was not completely modified by CTAB. The interlayer spacing of CZrP is 1.14 nm larger than that of ZrP, indicating that CTAB has a pre-supporting effect. The diffraction peak of the (002) plane of UTPCZrP containing urushiol titanium polymer appears at a 2θ value of 2.7°, with a corresponding interlayer spacing of 3.27 nm. The interplanar spacing of UTPCZrP is 2.51 nm larger than that of ZrP. These results indicate that the urushiol titanium polymer has been successfully embedded into ZrP.

[0054] The EDS-Mapping diagram of the prepared UTPCZrP is shown below. Figure 3 .from Figure 3As can be seen, the nanosheets in the selected region contain six elements: P, Zr, O, Si, C, and Ti, which are distributed throughout the sample. The distribution of P (A), Zr (B), and O (C) indicates the location of ZrP nanosheets; the distribution of Si (D) indicates the location of APSA; and C (E) and Ti (F) represent the location of UTi. The surface scan analysis of Ti element shows that the Ti element introduced by the in-situ polymerization of UTi is distributed in ZrP, indicating that the urushiol titanium polymer was successfully intercalated into ZrP.

[0055] SEM comparison images of ZrP with prepared CZrP and UTPCZrP are shown below. Figure 4 .Depend on Figure 4 It is evident that unsupported ZrP (A, B) exhibits a hexagonal lamellar structure with dense interlayer connections, relatively thick layers, and a stacked appearance. After pre-support, the CTAB long chain is embedded in ZrP to synthesize CZrP (C, D), which does not disrupt the hexagonal lamellar structure of ZrP, but increases the interlayer spacing. However, the UTPCZrP (E, F) obtained after in-situ reduction does not show a similar stacking phenomenon; instead, it unfolds as thin sheets with a significantly increased interlayer spacing. This is consistent with the XRD test results and proves the successful generation of UTPCZrP.

[0056] The IR comparison diagram of SA and the prepared APSA is shown below. Figure 5 .Depend on Figure 5 It can be seen that 3272 cm -1 2922 cm -1 The peak is attributed to the stretching vibrations of OH and CH atoms in saturated carbon atoms. After modification with DTES, it is located at 2922 cm⁻¹. -1 The absorption peak of the CH stretching vibration is enhanced at 1025 cm⁻¹. -1 The absorption peak shifted slightly and showed a more obvious enhancement, indicating that long-chain alkyl groups were successfully grafted and O-Si-O bonds were formed under these conditions.

[0057] The prepared UTPCZrP and the modifier AUZ were added to water respectively, and the state of the suspension was observed after different number of days to investigate the effect of APSA addition on dispersion. The results are shown in [Figure number missing]. Figure 6 .pass Figure 6It can be observed that at 1 day, both the suspensions without and with APSA were relatively uniformly dispersed. However, after 1 day, the dispersion of the suspensions differed. The upper layer of the suspension without APSA began to become clear, indicating that the suspended particles had settled, while no significant change was observed in the suspension with APSA. After 24 days, the clarity of the upper layer of the suspension without APSA increased significantly, and many suspended particles could be seen deposited at the bottom, while the sample with APSA began to show some precipitation. By 33 days, the upper layer of the suspension with APSA showed some stratification. In comparison, the suspension without APSA performed well overall.

[0058] Modified waterborne coatings were prepared by adding different amounts of AUZ to waterborne polyurethane (WPU), and then brushed onto the surface of an iron substrate to form a coating. The microstructure of the different coatings was observed using scanning electron microscopy, and the results are as follows: Figure 7 As shown. By Figure 7 As can be seen, the surface of pure WPU is not smooth, with many lines and deep cracks, indicating serious defects (A). This may be due to the evaporation of moisture contained in the coating during natural drying. After adding 3 wt% AUZ, the coating lines disappeared, cracks decreased, and smoothness improved (B). This is because the layered material compensated for the defects of the WPU coating after curing, but it can still be seen that its surface is not smooth enough and has some defects. When adding 5 wt% AUZ, the coating cracks were further reduced, the smoothness was significantly improved, and the coating morphology was the best (C). When the AUZ dosage was further increased to 7%, a small amount of layered material precipitated on the surface (D). It can be seen that the use of an appropriate amount of AUZ can compensate for the defects in the morphology of WPU coating, resulting in a denser and more uniform coating with better corrosion resistance.

[0059] Figure 8 Comparison of Tafel polarization curves for WPU coatings prepared with different amounts of AUZ. Corrosion current density (I0), corrosion potential (E0), and polarization resistance (R) of different samples were calculated from the Tafel polarization curves according to the Butler-Volmer equation. p The values ​​of corrosion current (CR) and corrosion rate (CR) are summarized in Table 1. Table 1 shows that the bare metal substrate exhibits a very high corrosion current, which is significantly reduced after coating the surface. For water-based coatings without the modifier AUZ, the corrosion current also decreases by two orders of magnitude, indicating that the coating effectively prevents corrosive media from penetrating the substrate and plays a significant role in improving corrosion resistance. After adding the modifier, the corrosion current decreases by another order of magnitude, and the rate of decrease first increases and then decreases with increasing addition amount, reaching its lowest value of 7.69 × 10⁻⁶ at an addition amount of 5 wt%. -9 A·cm-2 Compared to bare metal substrates, the corrosion resistance decreased by three orders of magnitude, and compared to unmodified coatings, it decreased by two orders of magnitude. This indicates that the modifier has good compatibility with WPU and can fully utilize the labyrinth effect brought by two-dimensional materials. Furthermore, the modified coating with an addition of 5 wt% showed the best anti-corrosion effect. Simultaneously, compared to water-based coatings without AUZ modifier, the modified coating with AUZ modifier showed a 1-2 order of magnitude increase in polarization resistance and a 1-2 order of magnitude decrease in corrosion rate, exhibiting higher overall polarization resistance and lower corrosion rate, indicating further improved corrosion resistance. In particular, at an addition of 5 wt%, the polarization resistance of the modified coating was 3.17 × 10⁻⁶. 6 Ω, corrosion rate is 2.39×10 -5 mm / year, with the greatest improvement in corrosion resistance. The protection efficiency more directly reflects the protective performance of the modified coating; at an addition level of 5 wt%, the modified coating exhibits a protection efficiency as high as 99.92%. This demonstrates that the modifier AUZ can significantly improve the corrosion resistance of water-based coatings as a highly efficient corrosion inhibitor.

[0060] Table 1

[0061]

[0062] Figure 9 Electrochemical impedance spectroscopy (EIS) plots of WPU coatings prepared with different amounts of AUZ, immersed in 3.5 wt% NaCl for different numbers of days, are shown. From the EIS spectra at 1 h (A, B), it can be seen that all coatings exhibit a capacitive arc, indicating that the coatings have a good barrier effect. Furthermore, the capacitive arc radius of the modified coatings with added modifiers is significantly increased, especially the modified coating with 5 wt% AUZ, which has the largest capacitive arc radius and the best anti-corrosion performance, with an impedance value reaching 5.64 × 10⁻⁶. 6 Ω∙cm 2 After soaking for 2 days (C), it can be seen that the capacitive arc of the coatings has decreased. The EIS spectrum of WPU shows two semicircular arcs, indicating that corrosive substances have penetrated the coating, leading to corrosion. In contrast, the modified coating with added AUZ still shows only one capacitive arc, demonstrating better protection. Furthermore, it is evident that the 5 wt% modified coating still exhibits the largest capacitive arc radius. This is because UTPCZrP can block O2 and Cl... -The penetration of corrosive substances such as H2O creates a complex labyrinth effect, prolonging the corrosion protection time. After immersion for 24 days (E), only one capacitive arc was observed. Although the impedance value of the modified coating decreased to some extent, corrosion still did not occur (it is worth noting that the capacitive arc radius of the modified coating is longer than the impedance arc radius of the WPU coating after 1 hour, especially the 5 wt% coating, which still shows an order of magnitude improvement). After immersion in salt water for up to 49 days (G, H), the modified coating showed corrosion. The above results fully demonstrate that the AUZ modifier has a significant effect on improving the corrosion protection performance of WPU coatings, maintaining corrosion resistance for more than 49 days and exhibiting a good synergistic corrosion protection effect.

[0063] The effects of adding CTAB and APSA on the anti-corrosion performance of the modified coating were investigated, and the results are shown in [Figure number missing]. Figure 10 From the EIS spectra at 1 hour (A, B), it can be seen that compared with the modified coatings prepared without either addition, the impedance value of the modified coatings prepared by adding only CTAB or using APSA increased by about one order of magnitude. This is because after pre-supporting ZrP, the urushiol titanium polymer was successfully reduced in the ZrP interlayer. Therefore, even if the mixing is uneven, it can still utilize the "maze effect" to prolong the time for the corrosive medium to enter the water-based coating, thereby improving the corrosion performance. After only amphoteric modification of SA, the high dispersion effect brought by the dispersant greatly reduces the occurrence of agglomeration, thus achieving an overall improvement in anti-corrosion performance. After immersion for 3 days (C), it can be seen that the capacitive arc of the coatings has decreased. The EIS spectrum of the modified coatings without any addition shows two semi-circular arcs, indicating that the coating has been corroded. The coating with only one modification still has only one capacitive arc, showing a better protective effect, indicating that pre-support or amphoteric modification can significantly improve the anti-corrosion performance of the coatings. After immersion for 7 days (E, F), the samples all show two capacitive arcs, indicating that they have been corroded. The above results fully demonstrate that using CTAB for pre-support and modifying SA with amphiphilic properties can synergistically improve the anti-corrosion performance of waterborne coatings.

[0064] Example 2

[0065] (1) Weigh 1 g of ZrP and disperse it in 300 mL of distilled water. Sonicate for a certain time until the dispersion is uniform. Then add 3.22 g of CTAB to the above dispersion and sonicate for 1 h. Centrifuge and wash the obtained product three times with ethanol. Then vacuum dry overnight. The intercalated compound is denoted as CZrP.

[0066] (2) Take 3 g of CZrP obtained in step (1), add 4 g of tetrabutyl titanate and 6 g of xylene into a 250 mL three-necked round-bottom flask, set up the reaction apparatus, and install a thermometer, a dropping funnel and a reflux condenser in the three necks respectively. Stir the mixture vigorously at room temperature until homogeneous, and then add a solution prepared by 7.44 g of xylene and 7.44 g of urushiol dropwise. At the same time, gradually heat the system to 80 °C and react for 1 h. Then gradually heat the system to 120 °C and react for 2 h. Then heat it to 138 °C and react for 1 h. The product is recorded as UTPCZrP.

[0067] (3) Measure 3 g of SA and add it to a mixture of ethanol and deionized water in a volume ratio of 9:1. Stir evenly at room temperature, and adjust the pH value to 9.0±0.3 with ammonia water. Then add 2 mL of DTES dropwise using a dropper. React at room temperature for 24 h. Wash the product three times with ethanol and vacuum dry overnight. The obtained product is called APSA.

[0068] (4) Add the UTPCZrP obtained in step (2), the APSA obtained in step (3), and deionized water into a beaker at a ratio of 1 g: 1 g: 25 mL and stir evenly. Then place the mixture in a ball mill and ball mill it. The resulting product is denoted as AUZ.

[0069] (5) Add 5 wt% AUZ to waterborne epoxy resin (WEP), stir evenly, and obtain modified waterborne coating.

[0070] The modified water-based coating prepared in this embodiment has an adhesion grade of 0, an impact resistance distance of 80cm, a flexibility of 0.5mm, and a pencil hardness of 6H.

[0071] Example 3

[0072] (1) Weigh 1 g of ZrP and disperse it in 300 mL of distilled water. Sonicate for a certain time until the dispersion is uniform. Then add 3.22 g of CTAB to the above dispersion and sonicate for 1 h. Centrifuge and wash the obtained product three times with ethanol. Then vacuum dry overnight. The intercalated compound is denoted as CZrP.

[0073] (2) Take 3 g of CZrP obtained in step (1), add 4 g of tetrabutyl titanate and 6 g of xylene into a 250 mL three-necked round-bottom flask, set up the reaction apparatus, and install a thermometer, a dropping funnel and a reflux condenser in the three necks respectively. Stir the mixture vigorously at room temperature until homogeneous, and then add a solution prepared by 7.44 g of xylene and 7.44 g of urushiol dropwise. At the same time, gradually heat the system to 80 °C and react for 1 h. Then gradually heat the system to 120 °C and react for 2 h. Then heat it to 138 °C and react for 1 h. The product is recorded as UTPCZrP.

[0074] (3) Measure 3 g of SA and add it to a mixture of ethanol and deionized water in a volume ratio of 9:1. Stir evenly at room temperature, and adjust the pH value to 9.0±0.3 with ammonia water. Then add 2 mL of DTES dropwise using a dropper. React at room temperature for 24 h. Wash the product three times with ethanol and vacuum dry overnight. The obtained product is called APSA.

[0075] (4) Add the UTPCZrP obtained in step (2), the APSA obtained in step (3), and deionized water into a beaker at a ratio of 1 g: 1 g: 25 mL and stir evenly. Then place the mixture in a ball mill and ball mill it. The resulting product is denoted as AUZ.

[0076] (5) Add 5 wt% AUZ to waterborne polyester (WPE) and stir evenly to obtain modified waterborne coating.

[0077] The modified water-based coating prepared in this embodiment has an adhesion grade of 0, an impact resistance distance of 80cm, a flexibility of 0.5mm, and a pencil hardness of 6H.

[0078] Example 4

[0079] (1) Weigh 1 g of ZrP and disperse it in 300 mL of distilled water. Sonicate for a certain time until the dispersion is uniform. Then add 3.22 g of CTAB to the above dispersion and sonicate for 1 h. Centrifuge and wash the obtained product three times with ethanol. Then vacuum dry overnight. The intercalated compound is denoted as CZrP.

[0080] (2) Take 3 g of CZrP obtained in step (1), add 4 g of tetrabutyl titanate and 6 g of xylene into a 250 mL three-necked round-bottom flask, set up the reaction apparatus, and install a thermometer, a dropping funnel and a reflux condenser in the three necks respectively. Stir the mixture vigorously at room temperature until homogeneous, then add a solution prepared by 7.44 g of xylene and 7.44 g of urushiol dropwise, while gradually heating the system to 80 °C and reacting for 1 h. Then gradually heat the system to 120 °C and react for 2 h, and then heat it to 138 °C and react for 1 h. The product is named UTPCZrP.

[0081] (3) Measure 3 g of SA and add it to a mixture of ethanol and deionized water in a volume ratio of 9:1. Stir evenly at room temperature, and adjust the pH value to 9.0±0.3 with ammonia water. Then add 2 mL of DTES dropwise using a dropper. React at room temperature for 24 h. Wash the product three times with ethanol and vacuum dry overnight. The obtained product is called APSA.

[0082] (4) Add the UTPCZrP obtained in step (2), the APSA obtained in step (3), and deionized water into a beaker at a ratio of 1g:1g:25mL and stir evenly. Then place the mixture in a ball mill and ball mill it. The resulting product is denoted as AUZ.

[0083] (5) Add 5 wt% AUZ to waterborne silicone resin (WSR), stir evenly, and obtain modified waterborne coating.

[0084] The modified water-based coating prepared in this embodiment has an adhesion grade of 0, an impact resistance distance of 80cm, a flexibility of 0.5mm, and a pencil hardness of 6H.

[0085] The comparison chart of Tafel polarization curves of the modified waterborne coatings obtained in Examples 2-4 is shown below. Figure 11 Its corrosion current density (I0), corrosion potential (E0), and polarization resistance (R) p The corrosion current and corrosion rate (CR) are shown in Table 2. The data in Table 2 show that the bare metal exhibits the highest corrosion current. After the surface is covered with coating, the corrosion current shows varying degrees of decrease, with the modified water-based coating showing a more significant decrease, further indicating that the addition of AUZ can improve the anti-corrosion performance of the coating to some extent. Simultaneously, the modified coating with added AUZ exhibits higher polarization resistance and a lower corrosion rate, indicating that AUZ can improve the corrosion resistance of the coating. Compared with the unmodified water-based coating, the protection efficiency exceeds 80% after adding the modifier.

[0086] Table 2

[0087]

[0088] Figure 12The images show the electrochemical impedance spectroscopy (EIS) results of the modified waterborne coatings obtained in Examples 2-4 after immersion in 3.5 wt% NaCl for different numbers of days. From the EIS spectra at 1 hour (A, B), it can be seen that all coatings exhibit a single capacitive arc, indicating good anti-corrosion properties. Furthermore, the addition of AUZ increased the impedance of the modified coatings by 1-2 orders of magnitude, especially for WPE and WSR, where the increase was two orders of magnitude. After 2 days of immersion (C), the capacitive arcs of the coatings decreased. The EIS spectra of the unmodified coatings showed two semicircular arcs, indicating corrosion. The modified coatings with AUZ still showed only one capacitive arc, demonstrating good protection. After 20 days of immersion (E, F), only one capacitive arc was observed throughout. Although the impedance of the modified coatings decreased to some extent, no corrosion was observed. After 48 days of immersion in salt water (G and H), the AUZ / WPE sample showed two capacitive arcs, indicating corrosion. However, the other two modified coatings still showed only one capacitive arc, indicating they retain some corrosion resistance. These results fully demonstrate that the AUZ modifier significantly improves the corrosion resistance of different types of water-based coatings, maintaining corrosion resistance for more than 48 days.

[0089] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A sodium alginate / urushiol-based aqueous coating modifier, characterized by: The preparation comprises the following steps: 1) first, the α-zirconium phosphate is pre-supported by using cetyltrimethylammonium bromide, and a titanium urushiol is generated in situ between the layers of the α-zirconium phosphate by reduction to obtain a urushiol-based corrosion inhibitor; 2) the sodium alginate is grafted by using dodecyltriethoxysilane to prepare amphiphilic sodium alginate; 3) the urushiol-based corrosion inhibitor prepared in step 1) and the amphiphilic sodium alginate prepared in step 2) are stirred and mixed uniformly in deionized water, and then ball milling is performed to prepare the water-based coating modifier; The specific operation steps of step 1) are as follows: a) the α-zirconium phosphate is ultrasonically dispersed in water, then cetyltrimethylammonium bromide is added, ultrasonic treatment is performed for 1 h, centrifugal washing is performed, and drying is performed to prepare an intercalation product; b) the obtained intercalation product and tetrabutyl titanate are mixed by vigorous stirring in dimethylbenzene, then dimethylbenzene solution of urushiol is added dropwise, and the temperature is increased to 80 ℃, and the reaction is kept for 1 h, then the temperature is continuously increased to 120 ℃, and the reaction is kept for 2 h, and then the temperature is increased to 138 ℃, and the reaction is kept for 1 h to obtain the urushiol-based corrosion inhibitor; Step 2) is specifically that the sodium alginate is dissolved in an ethanol solution, ammonia water is added to adjust the pH to 9±0.3, then dodecyltriethoxysilane is added dropwise, and the reaction is performed at room temperature for 24 h, and the product is washed with ethanol and dried to obtain the amphiphilic sodium alginate; The mass ratio of the urushiol-based corrosion inhibitor, the amphiphilic sodium alginate, and deionized water used in step 3) is 1:1:

25.

2. The sodium alginate / furfuryl alcohol based waterborne coating modifier according to claim 1, characterized in that: The mass ratio of cetyltrimethylammonium bromide to α-zirconium phosphate used in step a) is 3.22:

1.

3. The sodium alginate / furfuryl alcohol based waterborne coating modifier according to claim 1, characterized in that: The mass ratio of the intercalation product, tetrabutyl titanate, and urushiol used in step b) is 3:4:7.

44.

4. The sodium alginate / furfuryl alcohol based aqueous coating modifier according to claim 1, characterized in that: The volume ratio of ethanol to water in the ethanol solution is 9:1; and the dosage ratio of sodium alginate to dodecyltriethoxysilane is 3 g:2 mL.

5. Use of the sodium alginate / urushiol-based aqueous coating modifier according to claim 1 in an aqueous coating, characterized in that: The sodium alginate / urushiol-based water-based coating modifier is added to the water-based coating to prepare a modified water-based coating for the protection of metal substrates.

6. Use according to claim 5, characterized in that: The addition amount of the sodium alginate / urushiol-based water-based coating modifier in the water-based coating is 5 wt%.

7. Use according to claim 5 or 6, characterized in that: The water-based coating comprises any one or several of water-based polyurethane, water-based epoxy resin, water-based polyester, and water-based silicone resin.

Images