PO4 3- and 8-OQ intercalated zinc-aluminum hydrotalcite, PO4 3- Preparation method of 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating and its coating

Abstract

The application discloses a PO4 3‑ and a preparation method of a flame-retardant epoxy acrylate coating layer of 8-OQ intercalated zinc-aluminum hydrotalcite, and the coating layer. Phosphate ions are intercalated between layers by using the ion-exchangeability between layers, and other intercalation agents are used to increase the intercalation rate of phosphate ions before the phosphate ions are embedded into the layers. 8-hydroxyquinoline as an intercalation agent can effectively expand the interlayer spacing of hydrotalcite, and provide more space for anion exchange. The Zn / Al-PO4 3‑ -LDHs intercalated with 8-hydroxyquinoline has the optimal flame-retardant and mechanical properties of the coating layer of the EA compound system. The hydrotalcite can make the carbon layer more uniform, more dense and more solid, and increase the carbon content of the coating layer, so as to improve the flame retardancy and thermal stability of the composite coating, and provide a new method for the research on the hydrotalcite modified EA fireproof coating.

Description

Technical Field

[0001] This invention belongs to the technical field of epoxy acrylate flame retardant materials, specifically relating to an intercalated zinc-aluminum hydrotalcite flame retardant epoxy acrylate coating. Background Technology

[0002] Transparent fire-retardant coatings not only preserve the original appearance, designs, and lettering of building substrates but also serve both fire-retardant and decorative purposes. They are a type of coating that combines decorative and fire-retardant properties and can be widely used for fire protection of ancient buildings. Therefore, people are paying increasing attention to transparent fire-retardant coatings.

[0003] Epoxy acrylate (EA) is a widely used photocurable prepolymer with advantages such as easy processing, low cost, chemical resistance, fast curing speed, and strong adhesion. It has been widely used in coatings, inks, adhesives, and other fields. However, due to its flammability, its application range is greatly limited. Therefore, the modification of EA has attracted increasing attention from scholars and has become one of the hot topics in contemporary coatings research.

[0004] Layered double hydroxides (LDHs) are a collective term for hydrotalcite (HT) and hydrotalcite-like compounds. They are two-dimensional layered nanomaterials composed of positively charged metal oxide layers and negatively charged anions. When the fire-retardant coating is heated, the free water between the hydrotalcite layers is first decomposed, carrying away some heat energy. Upon continued heating, the bound water between the hydrotalcite layers is removed, carrying away some heat energy. Simultaneously, some carbonates decompose into CO2, a non-flammable gas that can escape as water vapor. This not only removes heat but also dilutes the oxygen concentration in the air. Furthermore, the addition of hydrotalcite makes the carbon layer more uniform, denser, and stronger, and also allows the carbon layer to better resist flames. This gives the coating stronger fire resistance, increases flame retardant time, and can also increase the carbon content of the fire-retardant coating. Compared with inorganic flame retardants such as Mg(OH)2, LDHs have a wider thermal decomposition temperature range and better fire resistance. They are halogen-free, non-toxic, smoke-suppressing flame retardants that can be used to improve the flame retardancy and thermal stability of composite coatings.

[0005] Given that there are currently no reports on the research of phosphate-intercalated hydrotalcite flame-retardant EA coatings, it is necessary to conduct research and improvement on them. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a PO4 3- and 8-OQ intercalated zinc-aluminum hydrotalcite, PO4 3-The preparation method of 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating and the coating itself.

[0007] One of the technical solutions adopted by this invention to solve its technical problem is:

[0008] PO4 3- And a method for preparing 8-OQ intercalated zinc-aluminum hydrotalcite, the method comprising:

[0009] Zinc nitrate and aluminum nitrate were dissolved in water to prepare a mixed salt solution; sodium hydroxide and sodium carbonate were dissolved in water to prepare a coprecipitant; sodium phosphate was dissolved in water to prepare a sodium phosphate solution; and 8-hydroxyquinoline was dissolved in anhydrous ethanol to prepare a mixed solution.

[0010] The mixed salt solution, co-precipitant, sodium phosphate solution, and mixed solution were added dropwise to a three-necked flask at a constant rate. The mixture was stirred at a constant temperature, and the pH of the system was adjusted to 4. After the addition was complete, stirring was continued for 2 hours. Crystallization was carried out at 80 °C for 12 hours. The mixture was then filtered, and the filter cake was washed with deionized water until the pH reached 7-8. The filter cake was dried at 70 °C for 12 hours to obtain PO4. 3- And 8-OQ intercalated zinc-aluminum hydrotalcite.

[0011] Furthermore, the molar ratio of aluminum nitrate to zinc nitrate is 1:6~8.

[0012] Furthermore, the molar ratio of sodium carbonate to sodium hydroxide is 1:2~4.

[0013] Furthermore, the concentration of the sodium phosphate solution is 140~160 g / L.

[0014] The second technical solution adopted by this invention to solve its technical problem is:

[0015] A type of PO4 3- And a method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating, the method comprising: mixing and dispersing acrylamide and acrylic acid, and then sequentially adding the above-mentioned PO4 3- PO4 prepared by the method of 8-OQ intercalated zinc aluminum hydrotalcite 3- The mixture contains 8-OQ intercalated zinc-aluminum hydrotalcite, epoxy acrylate, and a photoinitiator, which are uniformly dispersed within the mixture. The resulting mixture is then uniformly coated onto a substrate and cured under light to obtain PO4. 3- And 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating.

[0016] Furthermore, the acrylamide, acrylic acid, and PO4... 3- The mass ratio of 8-OQ intercalated zinc-aluminum hydrotalcite, epoxy acrylate, and photoinitiator is 1.4~1.6:1.8~2.2:0.2~1.0:5.5~6.3:0.2~0.4.

[0017] Furthermore, the PO4 3- 8-OQ intercalated zinc-aluminum hydrotalcite was added in small amounts and multiple times to the mixed solution of acrylamide and acrylic acid.

[0018] Furthermore, the pH of the system was adjusted to 4 using HNO3 solution.

[0019] The third technical solution adopted by this invention to solve its technical problem is:

[0020] A type of PO4 3- and 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating, wherein the PO4 3- and the 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is made from the above-mentioned PO4 3- The 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating was prepared by a specific method.

[0021] Compared with the prior art, this technical solution has the following advantages: This invention utilizes the anion exchangeability between the layers to intercalate phosphate groups. Before the phosphate groups are embedded into the layers, other intercalating agents are used to increase the phosphate intercalation rate. 8-Hydroxyquinoline, as an intercalating agent, can effectively expand the interlayer spacing of hydrotalcite, providing more space for anion exchange. The 8-hydroxyquinoline intercalation of Zn / Al-PO4... 3- - The coating system of LDHs and EA has the best flame retardancy and mechanical properties. The addition of hydrotalcite can make the carbon layer more uniform, dense and strong, and increase the carbon content of the coating. It can be used to improve the flame retardancy and thermal stability of composite coatings, and provides a new method for the research of hydrotalcite modified EA fireproof coatings. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 Scanning electron microscope (SEM) image of Zn / Al-LDHs;

[0024] Figure 2 Zn / Al-PO4 3- -LDHs+8 scanning electron microscope (SEM) image;

[0025] Figure 3 XRD patterns of phosphate-intercalated LDHs;

[0026] Figure 4 XRD pattern of LDHs / EA composite material;

[0027] Figure 5 Infrared spectra of LDHs;

[0028] Figure 6Infrared spectrum of LDHs / EA coating;

[0029] Figure 7 Zn / Al-PO4 3- Dynamic infrared image of -LDHs+8;

[0030] Figure 8 The UV-Vis spectrum of the Zn / Al-LDHs / EA coating;

[0031] Figure 9 Zn / Al-PO4 3- -UV-Vis spectrum of LDHs / EA coating;

[0032] Figure 10 Zn / Al-PO4 3- UV-Vis spectrum of -LDHs+8 / EA coating;

[0033] Figure 11 TG curves for the Zn / Al-LDHs / EA coating;

[0034] Figure 12 Zn / Al-PO4 3- TG curves of LDHs / EA coatings;

[0035] Figure 13 Zn / Al-PO4 3- TG curve of -LDHs+8 / EA coating;

[0036] Figure 14 TG-DSC plot of Zn / Al-LDHs / EA;

[0037] Figure 15 Zn / Al-PO4 3- -TG-DSC plot of LDHs / EA;

[0038] Figure 16 Zn / Al-PO4 3- TG-DSC plot of -LDHs+8 / EA. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1: Preparation of zinc-aluminum hydrotalcite

[0041] 8.926 g of zinc nitrate and 3.762 g of aluminum nitrate were weighed and dissolved in 100 mL of deionized water to prepare a mixed salt solution, denoted as solution A. 2.400 g of sodium hydroxide and 2.120 g of sodium carbonate were weighed and dissolved in 100 mL of deionized water to prepare a co-precipitant, denoted as solution B. The completely dissolved solutions A and B were poured into two separatory funnels and added dropwise to a three-necked flask at a constant temperature (80 ℃) with stirring (12 r / min). The pH of the system was adjusted to 12 with 1 mol / L sodium hydroxide. After the addition of solutions A and B was complete, stirring continued for 2 h. Crystallization was carried out at 80 ℃ for 12 h. The filter cake was filtered, washed with deionized water until the pH reached 7-8, and dried at 70 ℃ for 12 h to obtain zinc-aluminum hydrotalcite, denoted as Zn / Al-LDHs.

[0042] Example 2: PO4 3- Preparation of intercalated zinc-aluminum hydrotalcite

[0043] 15.205 g of sodium phosphate was dissolved in 100 mL of deionized water, denoted as solution C. The completely dissolved solutions A, B, and C were poured into a separatory funnel and then added dropwise to a three-necked flask at a constant temperature (80 ℃) with stirring (12 r / min). The pH of the system was adjusted to 4 with 1 mol / L HNO3. After adding solutions A, B, and C, stirring was continued for 2 h. Crystallization was carried out at 80 ℃ for 12 h. The mixture was filtered, and the filter cake was washed with deionized water until the pH reached 7-8. The filter cake was then dried at 70 ℃ for 12 h to obtain PO4. 3- Intercalated zinc-aluminum hydrotalcite, denoted as Zn / Al-PO4 3- -LDHs.

[0044] Example 3: PO4 3- Preparation of 8-OQ intercalated zinc-aluminum hydrotalcite

[0045] Weigh 0.058 g of 8-hydroxyquinoline and dissolve it in a small amount of anhydrous ethanol, denoted as solution E. Pour the completely dissolved solutions A, B, C, and E into a separatory funnel and add them dropwise to a three-necked flask at a uniform rate. Stir at a constant temperature (80 ℃) (12 r / min) and adjust the pH of the system to 4 with 1 mol / L HNO3. After adding solutions A, B, C, and E, continue stirring for 2 h. Crystallize at 80 ℃ for 12 h, filter, wash the filter cake with deionized water until the pH reaches 7-8, and dry the filter cake at 70 ℃ for 12 h to obtain PO4. 3- And 8-OQ intercalated zinc-aluminum hydrotalcite, denoted as Zn / Al-PO4 3- -LDHs+8.

[0046] Example 4: Preparation and curing method of epoxy acrylate coating

[0047] According to the formula in Table 1, a flame-retardant coating with a total mass of 10 g was prepared. The preparation method was as follows: First, prepare 16 dry and clean small beakers and label them. Tare and weigh the beakers. Mix 2.0 g of acrylamide and 1.5 g of acrylic acid and place them in a 1 kW ultrasonic chamber for 0.5 h to disperse completely. Then weigh the intercalated hydrotalcite of the formula and disperse it in the above solution in small amounts several times. After ultrasonic dispersion for 0.25 h, add the epoxy acrylate (EA) of the formula to the system. Stir first, then ultrasonically disperse for 1 h. Then add 0.3 g of 1173 photoinitiator and ultrasonically disperse for another 5 min. Ultrasonic dispersion is continued until the material is uniformly mixed and free of bubbles.

[0048] Table 1 Formulation of LDHs / EA System

[0049]

[0050] Preparation of UV-cured specimens: Lay a layer of tin foil on a clean mold, apply a small amount of silicone oil evenly to the mold groove, pour the compound coating into the mold groove, turn on the UV lamp to preheat for a period of time, for example, 20 seconds, and then irradiate to cure into specimens. The curing time is about 10 seconds.

[0051] To understand the composition and structure of each sample, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet / visible spectrophotometer, thermogravimetric analysis (TG), vertical water combustion tester, and HSC-4 thermal analyzer were used to characterize the samples.

[0052] Experimental Example 1: Scanning Electron Microscopy Analysis

[0053] The external dimensions of the samples were characterized using an SU3500 scanning electron microscope. Figure 1 The scanning electron microscope (SEM) images of Zn / Al-LDHs show that the morphology of unmodified hydrotalcite is mostly hexagonal lamellar structure, with grain sizes ranging from 200 to 400 nm and a thickness of approximately 30 nm. Hydrotalcite grows along either the a-axis or the c-axis, with the growth rates of the (110) crystal plane and the (003) mirror plane depending on the strong chemical interaction within the lamellar structure. Generally, hydrotalcite grows better along the a-axis than along the c-axis, thus making it easier for hydrotalcite to form lamellar grains.

[0054] Figure 2 Zn / Al-PO4 3-Scanning electron microscopy (SEM) images of -LDHs+8 reveal a clear lamellar structure. The addition of 8-hydroxyquinoline as an intercalating agent in this system leads to micelle formation, and the growth of hydrotalcite particles occurs within the aqueous cavities. The morphology of the synthesized particles depends on the shape of the aqueous cavities. Furthermore, hydroxyl groups readily adsorb onto the surface of the hydrotalcite particles, thereby altering their surface properties. The lamellar structure has a high surface energy and spontaneously aggregates to reduce the surface energy and reach a stable state. Therefore, the hydrotalcite prepared by this method exhibits a well-dispersed lamellar structure.

[0055] Experimental Example 2: X-ray Diffraction Analysis

[0056] The sample powder was tested using an XRD-6100 X-ray diffractometer (Cu target, Kα rays, λ=0.15406 nm, voltage 40 kV, current 30 mA, scanning speed 2° / min, angle range: 5~80°). Figure 3 Zn / Al-LDHs, Zn / Al-PO4 3- -LDHs and Zn / Al-PO4 3- X-ray diffraction pattern of Zn / Al-LDHs+8. Clearly, the synthesized LDHs exhibit characteristic hexagonal symmetric phase layers and structural diffraction peaks, with low and stable baselines and narrow, sharp peaks, indicating a single crystal phase in the synthesized Zn / Al-LDHs. The typical peaks (003), (006), (009), and (110) at the 2θ angle in the XRD diffraction pattern are narrow and sharp, demonstrating the high crystallinity of Zn / Al-LDHs. The (110) crystal plane represents a perfect halide-like internal structure. Zn / Al-PO4 3- -LDHs and Zn / Al-PO4 3- The X-ray diffraction pattern of -LDHs+8 shows that crystal planes (003), (006), and (009) still exist, but are clearly displaced. Table 2 shows that both 8-hydroxyquinoline and phosphate were successfully intercalated into the layered double hydroxide (LDH) layers. 8-hydroxyquinoline, as a precursor intercalating agent, widened the interlayer spacing between LDH layers. When phosphate entered the interlayer through ion exchange, the interlayer spacing was significantly wider compared to LDH layers without 8-hydroxyquinoline, achieving an intercalation rate of 54.54%.

[0057] Table 2 Spacing between different types of hydrotalcite layers

[0058]

[0059] Figure 4 This is the X-ray diffraction pattern of the LDHs / EA compound product. The characteristic diffraction peaks of the polymer can be clearly observed from the pattern, but those of the hydrotalcite cannot be observed. This indicates that the diffraction peaks of the hydrotalcite are covered by the epoxy acrylate resin and are not easy to observe.

[0060] Experimental Example 3: Infrared Spectroscopy Analysis

[0061] A TENSOR 27 Fourier transform spectrometer was used to measure wavelengths ranging from 500 to 4000 cm⁻¹. -1 . Figure 5 The infrared spectrum of hydrotalcite shows a series of absorption peaks, with wavenumber 1360 cm⁻¹ in curve a. -1 At this point, the absorption peak corresponds to that caused by the stretching vibration of carbonates between LDH layers, at 1640 cm⁻¹. -1 The corresponding vibrational peak of interlayer water molecules is 3399 cm⁻¹. -1 This corresponds to the intermolecular OH stretching vibration, while 8-hydroxyquinoline contains a phenolic hydroxyl group. At 1022 cm⁻¹ -1 The peak at the corresponding position is the characteristic absorption peak of the PO bond. This characteristic peak can be observed at the corresponding positions in curves b and c in the figure, indicating that the phosphate has been inserted into Zn / Al-LDHs.

[0062] Figure 6 Infrared spectrum of LDHs / EA coating, 1720 cm⁻¹ -1 This corresponds to the C=O stretching vibration of esters, 1180 cm⁻¹ -1 This corresponds to the COC stretching vibration of esters, 1509 cm⁻¹ -1 The characteristic absorption peak corresponding to phenyl at 915 cm⁻¹ -1 The peak at this location corresponds to the stretching vibration of CO and is a characteristic peak of the epoxy group.

[0063] Experimental Example 4: Dynamic Infrared Analysis

[0064] The test sample was broken into pieces the size of a mung bean, and the surface of the sample was measured by infrared spectroscopy at different calcination temperatures. Figure 7 Zn / Al-PO4 modified with 8-hydroxyquinoline 3- -LDHs, as shown in the figure, appeared at 3446 cm. -1 and 1714 cm -1 The nearby characteristic peaks are stretching vibration peaks of hydroxyl groups and interlayer water in LDHs, which are completely degraded at 300℃; 2930 cm⁻¹ -1 The characteristic peak is the CH antisymmetric stretching vibration absorption peak, which is completely degraded at 250 °C; 1508 cm⁻¹ -1 The skeletal vibration at this position is a substitution for benzene ν (C=C) and it degrades completely at 370 °C; 1035 cm -1 The peak at 565 cm⁻¹ is a characteristic peak for phosphate, indicating complete degradation at 350 °C; the peak at 565 cm⁻¹ is also present. -1 and 823 cm -1The nearby peaks are absorption peaks of the stretching vibration of the Al-O bond, and the structure is completely degraded at 370 °C.

[0065] Experimental Example 5: Coating Transmittance Analysis

[0066] The composite coating was tested using a UV-2550 ultraviolet / visible spectrophotometer with a wavelength range of 200~800nm. Figure 8 The image shows the UV-Vis spectrum of the Zn / Al-LDHs / EA coating. It can be seen from the image that the change in the hydrotalcite ratio has no obvious effect on the light transmittance of the coating. This may be related to the film preparation method and the coating thickness, so it will not be discussed in detail here.

[0067] Figure 9 Zn / Al-PO4 3- The UV-Vis spectrum of the LDHs / EA coating shows that in the 200–300 nm UV region, the transmittance of the coating is almost zero, indicating that the coating has good UV protection. In the 300–400 nm region, the transmittance of the coating increases with increasing wavelength. In the 400–800 nm region, the transmittance of the control group without LDHs is as high as 89.92%, while the transmittance of the coating is between 50% and 90%. The transmittance of the coating decreases with increasing LDHs content. This is because as the proportion of LDHs in the compound system increases, the polymer containing LDHs structure in the system changes the compatibility of the system after photocuring, thus leading to a decrease in the transmittance of the coating.

[0068] Figure 10 Zn / Al-PO4 3- The UV-Vis spectrum of the -LDHs+8 / EA coating, and... Figure 9 In comparison, it can be seen that adding 8-hydroxyquinoline to the Zn / Al-PO4 composite coating in the 400~800 nm range is more effective. 3- The transmittance of LDHs is between 57% and 87%. The transmittance decreases slightly but the difference is not significant. The transmittance of the coating decreases with the increase of LDHs addition.

[0069] Experimental Example 6: Flame Retardant and Mechanical Property Analysis of Solid Coatings

[0070] According to GB / T 6739-1996, the mechanical properties of samples are measured by the pencil hardness method. The coating is placed horizontally and fixed on the test sample platform. A square-sharpened pencil is then fixed in a pencil holder, with the tip of the pencil lead contacting the coating surface at a 45° angle. The handwheel is rotated at a constant speed of 0.5 mm / s, causing the pencil lead to scratch the coating surface at five marks at different locations. The hardness of the pencil with fewer than two marks is recorded as the coating hardness grade.

[0071] After curing, different types of coatings were cut and dried at 7°C for 24 hours, and the weight was recorded as m1 (g). The coatings were then immersed in a beaker containing tap water (simulating a natural environment) for 24 hours. After wiping the water off the surface of the coatings, the weight was recorded as m2 (g). The water absorption rate of the coating is then calculated. The calculation formula is:

[0072]

[0073] Cut the cured strip into small pieces, weigh them, and record the weight as follows: (g) Place the sample bar into the crucible and weigh it, recording the total weight as follows: (g) The sample was placed in a high-temperature muffle furnace for calcination at a carbonization temperature of 500 °C and a heating rate of 10 °C / min. It was removed immediately when the temperature reached 500 °C. The total weight of the calcined sample and crucible was recorded as follows: (g) then the residual carbon content of the coating The calculation formula is:

[0074]

[0075] Using an oxygen index meter, according to ASTM D2863-77 standard, the LOI value was determined by burning the coated sample vertically on top under mixed O2 and N2 gas conditions. The test was conducted using a vertical water combustion tester from Wuhan Glamour Testing Equipment Co., Ltd., according to UL-94 standard.

[0076] Table 3 shows the flame retardant and mechanical properties of the solid coatings. The system without added LDHs exhibits lower coating hardness, water absorption, and char residue. The flame retardant and mechanical properties of the solid coating vary depending on the type and mass of hydrotalcite in the system. Specifically, the solid coating exhibits the highest hardness when the mass of added hydrotalcite is 1.0 g. The Zn / Al-PO4 system with added 8-hydroxyquinoline shows the highest hardness. 3- The LDHs / EA composite system exhibits relatively high and stable water absorption. After calcination at 500 ℃, the 0 g hydrotalcite composite system showed a char residue of up to 62.07% and an LOI of 37. Comparison of samples 2-6 and 7-11 revealed that phosphate-intercalated hydrotalcite improved the flame retardant properties of the system (individual cases affected by the muffle furnace calcination position are not discussed). Among them, the phosphate-intercalated Zn / Al-LDHs composite system containing 8-hydroxyquinoline showed a char residue of up to 79.68%, which was significantly higher than that of the Zn / Al-LDHs and unmodified intercalated hydrotalcite composite systems. This is because 8-hydroxyquinoline, as an intercalating agent, expanded the distance between hydrotalcite layers, providing more sites for phosphate intercalation.

[0077] Table 3 Flame retardant and mechanical properties of solid coatings

[0078]

[0079] Experimental Example 7: Thermogravimetric (TG) Analysis of Coating

[0080] An SDT650 thermal analyzer was used in an air atmosphere at a heating rate of 10 °C / min to 800 °C. The sample mass was 20–30 mg. Figure 11 The graph shows the thermal stability (TG) curves of the unintercalated Zn / Al-LDHs / EA composite coating. As can be seen from the graph, the sample weight decreases very little in the 25–300 °C range, primarily due to the removal of surface water and interlayer bound water. In the 300–600 °C range, the sample weight decreases sharply, mainly due to the rapid degradation of the polymer at high temperatures, generating CO2 and other gaseous impurities. After 600 °C, the sample weight remains essentially unchanged, because after the previous degradation, only a small carbon layer remains, making further degradation unlikely. The order of thermal stability of the sample coatings in the graph is: Sample 6 > Sample 4 > Sample 5 > Sample 3 > Sample 2 > Sample 1. Compared to the coating without LDHs, the composite coating exhibits higher thermal stability, indicating that increasing the Zn / Al-LDHs content within a certain range increases the char residue and improves the flame retardant effect.

[0081] Figure 12 The TG curves are for samples 7, 8, 9, 10, 11, and sample 1. Figure 12 It can be seen that the thermal stability order of the phosphate-intercalated Zn / Al-LDHs composite coatings is: Sample 10 > Sample 9 > Sample 11 > Sample 8 > Sample 7. Compared with unintercalated Zn / Al-LDHs, the high-temperature resistance of the coating is improved in the composite system with phosphate intercalation. This is because water vapor and phosphoric acid are released during the thermal decomposition of the phosphate-intercalated hydrotalcite. This promotes the formation of the residual carbon layer and plays a synergistic flame-retardant role.

[0082] Figure 13 The TG curves are for samples 12, 13, 14, 15, 16 and sample 1. The thermal stability order of the composite coating of 8-hydroxyquinoline intercalated Zn / Al-LDHs is: sample 16 > sample 14 > sample 15 > sample 13 > sample 12.

[0083] Experimental Example 8: TG-DSC Analysis of Coating

[0084] An HSC-4 thermal analyzer was used, with the initial temperature set at 25 ℃, the final temperature at 650 ℃, and the sampling interval at 10 ℃ / min. Figure 14The figure shows the TG-DSC curve of Zn / Al-LDHs / EA, where the mass of LDHs is 0.4 g. As can be seen from the figure, the thermal decomposition of Zn / Al-LDHs / EA occurs in two stages: the first thermal degradation stage is between 350 and 400 °C, corresponding to the first absorption peak on the DSC curve (371 °C), during which the removal of interlayer adsorbed water and water of crystallization is mainly carried out; the second thermal degradation stage is between 405 and 515 °C, corresponding to the second absorption peak on the DSC curve (464 °C), during which the removal of OH groups from the interlayer is mainly carried out. - and interlayer CO3 2- This is caused by the decomposition of [something].

[0085] Figure 15 Zn / Al-PO4 3- The TG-DSC plot of -LDHs / EA, where the mass of LDH is 0.4 g. The plot shows that Zn / Al-PO4... 3- The thermal decomposition of LDHs / EA occurs in two stages: the first thermal degradation stage is between 350 and 400 °C, corresponding to the first absorption peak on the DSC curve (367 °C), during which the removal of interlayer adsorbed water and water of crystallization is mainly carried out; the second thermal degradation stage is between 450 and 550 °C, corresponding to the second absorption peak on the DSC curve (518 °C), during which the deOH groups are mainly removed from the laminae of phosphate-intercalated LDHs. - and interlayer CO3 2- This is due to the decomposition of phosphate-intercalated LDHs, at which point the layered structure of the LDHs is gradually disrupted.

[0086] Figure 16 Zn / Al-PO4 intercalated with 8-hydroxyquinoline 3- The TG-DSC plot of the modified LDHs / EA system shows that the thermal decomposition of the LDHs / EA system also proceeds in two stages: the first thermal degradation stage occurs between 350 and 400 °C, corresponding to the first absorption peak (370 °C) on the DSC curve; the second thermal degradation stage occurs between 500 and 550 °C, corresponding to the second absorption peak (520 °C) on the DSC curve.

[0087] This paper describes the synthesis of zinc aluminum double hydroxides (Zn / Al-LDHs) and phosphate-intercalated zinc aluminum double hydroxides (Zn / Al-PO4) via a co-precipitation method using zinc nitrate, aluminum nitrate, sodium carbonate, sodium phosphate, and 8-OQ. 3-Intercalation of Zn / Al-LDHs with 8-hydroxyquinoline, 8-OQ, and phosphate groups in Zn / Al-LDHs (Zn / Al-LDHs+8+16). The intercalation rate of 8-hydroxyquinoline and phosphate groups in Zn / Al-LDHs reached 54.54%. 8-hydroxyquinoline, as an intercalating agent, effectively widened the interlayer spacing of the hydrotalcite, providing more space for anion exchange. 8-hydroxyquinoline-intercalated Zn / Al-PO4 3- The coating system with LDHs and EA has the best flame retardant and mechanical properties. The ratio of phosphate to LDHs in this system is 1:1. When the mass of hydrotalcite mixed with EA is 0.4 g, the coating has the highest char rate of 79.68%, an oxygen index of 40, a vertical burning rating of V-0, a light transmittance of 85.69%, and a hardness of 5H. Compared with the modified EA system without hydrotalcite, the residual char rate of the coating increased by 17.61%, indicating that the addition of hydrotalcite makes the carbon layer more uniform, dense, and robust, and increases the carbon content of the coating, which can be used to improve the flame retardancy and thermal stability of composite coatings. Currently, there is no research on phosphate-intercalated hydrotalcite and EA composite coatings. This paper utilizes the anion exchangeability between the laminations to intercalate phosphate into the interlaminar space. Before the phosphate is embedded into the laminations, other intercalating agents are used to increase the phosphate intercalation rate. The influence of the phosphate intercalation rate on the flame retardant performance of the fireproof coating and the optimal ratio when compounded with EA are studied, providing a new method for the research of hydrotalcite-modified EA fireproof coatings.

[0088] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A type of PO4 3- The method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is characterized by, The method includes: mixing and dispersing acrylamide and acrylic acid, and then sequentially adding PO4 3- The mixture, consisting of 8-OQ intercalated zinc-aluminum hydrotalcite, epoxy acrylate, and a photoinitiator, is uniformly dispersed within the substrate. The resulting mixture is then uniformly coated onto a substrate and cured under light to obtain PO4. 3- and 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating; Wherein, the PO4 3- The preparation methods of 8-OQ intercalated zinc-aluminum hydrotalcite include: Zinc nitrate and aluminum nitrate were dissolved in water to prepare a mixed salt solution; sodium hydroxide and sodium carbonate were dissolved in water to prepare a coprecipitant; sodium phosphate was dissolved in water to prepare a sodium phosphate solution; and 8-hydroxyquinoline was dissolved in anhydrous ethanol to prepare a mixed solution. The mixed salt solution, co-precipitant, sodium phosphate solution, and mixed solution were added dropwise to a three-necked flask at a constant rate. The mixture was stirred at a constant temperature, and the pH of the system was adjusted to 4. After the addition was complete, stirring was continued for 2 hours. Crystallization was carried out at 80 °C for 12 hours. The mixture was then filtered, and the filter cake was washed with deionized water until the pH reached 7-8. The filter cake was dried at 70 °C for 12 hours to obtain PO4. 3- And 8-OQ intercalated zinc-aluminum hydrotalcite.

2. The PO4 according to claim 1 3- The method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is characterized by: The molar ratio of aluminum nitrate to zinc nitrate is 1:6~8.

3. The PO4 according to claim 1 3- The method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is characterized by: The molar ratio of sodium carbonate to sodium hydroxide is 1:2~4.

4. The PO4 according to claim 1 3- The method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is characterized by: The concentration of the sodium phosphate solution is 140~160 g / L.

5. The PO4 according to claim 1 3- The method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is characterized by: Acrylamide, acrylic acid, PO4 3- The mass ratio of 8-OQ intercalated zinc-aluminum hydrotalcite, epoxy acrylate, and photoinitiator is 1.4~1.6:1.8~2.2:0.2~1.0:5.5~6.3:0.2~0.

4.

6. The PO4 according to claim 1 3- The method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is characterized by: The PO4 3- 8-OQ intercalated zinc-aluminum hydrotalcite was added in small amounts and multiple times to the mixed solution of acrylamide and acrylic acid.

7. The PO4 according to claim 1 3- The method for preparing an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is characterized by: The pH of the system was adjusted to 4 using HNO3 solution.

8. A type of PO4 3- and an 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating, characterized in that: The PO4 3- and the 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating is made of PO4 as described in any one of claims 1 to 7. 3- The 8-OQ intercalated zinc-aluminum hydrotalcite flame-retardant epoxy acrylic coating was prepared by a specific method.

Images