Zno / graphene composite material, zn hybrid graphene flame-retardant epoxy acrylate coating and preparation method

Abstract

The application discloses a ZnO / graphene composite material, a Zn-hybridized graphene flame-retardant epoxy acrylate coating and a preparation method. The ZnO / graphene composite material is prepared, and is used as a flame retardant to be compounded with EA to prepare the Zn-hybridized graphene flame-retardant epoxy acrylate coating through light curing. The ZnO in the ZnO / graphene composite material grows in various crystal morphologies such as granular, fusiform, hexagonal and short rod on the surface and between layers of the graphene, the assembly sites are uniformly dispersed, the particle size is uniform, the specific surface area is relatively large, the agglomeration phenomenon is improved, and the mutual modification of the ZnO and the graphene is achieved. The addition of the ZnO / graphene composite material reduces the ultraviolet transmittance of the EA coating, increases the carbon residue rate and the LOI value of the coating, and makes the carbon residue pores dense and small and the thermal stability good, so that the structure and the performance of the composite EA coating are effectively improved, and the application range of the EA coating is widened.

Description

Technical Field

[0001] This invention belongs to the technical field of epoxy acrylate flame retardant materials, specifically relating to a ZnO / graphene composite material, a Zn hybrid graphene flame retardant epoxy acrylate coating, and its preparation method. Background Technology

[0002] A significant characteristic of epoxy acrylate (EA) coatings is their high light transmittance. However, EA coatings cured by conventional UV light have poor heat resistance and flame retardancy, making them highly flammable. In production and daily life, the fire-retardant coatings we choose vary depending on the substrate. The selection principle is to apply a fire-retardant coating for protection without affecting the appearance and use as much as possible. Although EA coatings meet our requirements for high light transmittance, they cannot be used directly as fire-retardant coatings. Flame retardants need to be added beforehand to improve their flame-retardant properties.

[0003] Compared with traditional flame retardants, nano flame retardants have significant advantages in regulating the heat resistance of materials. Nano zinc oxide (ZnO), as an inorganic flame retardant, has the characteristics of small particle size, large specific surface area, and high surface activity, which can improve the compatibility of the system and make the products of polymers more stable during thermal degradation.

[0004] Graphene does not burn when exposed to open flame, and the addition of graphene will improve the flame retardant properties of polymers. First, graphene promotes the rapid carbonization of polymers and releases non-flammable gases; second, the gases generated by thermal decomposition cause the carbon layer to expand, covering the surface and isolating air, thus playing a certain flame retardant role; finally, the graphene material burns in the polymer to form an interpenetrating network structure, and the formation of curved channels reduces the amount of gas permeation [3]. At the same time, graphene with a huge specific surface area can provide crystallization sites for nanoparticles, making them uniformly distributed and reducing their own aggregation, thereby maintaining high surface activity of nanoparticles. However, there are large van der Waals forces between graphene sheets, which have the disadvantage of easy aggregation and poor dispersion effect in the system. Therefore, it is necessary to continue to study and improve it. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a ZnO / graphene composite material, a Zn hybrid graphene flame-retardant epoxy acrylate coating, and a preparation method thereof.

[0006] One of the technical solutions adopted by this invention to solve its technical problem is:

[0007] A method for preparing a ZnO / graphene composite material, characterized in that the method comprises:

[0008] At 60°C, a mixture of silane coupling agent and anhydrous ethanol was added dropwise to a mixture of anhydrous ethanol and graphene and stirred for 24 hours. The mixture was then filtered and dried to obtain silanized modified graphene.

[0009] At 75°C, zinc acetate solution was added dropwise to a mixture of anhydrous ethanol and silanized modified graphene to obtain a mixed solution. Ammonia water was then added dropwise to the mixed solution, and the mixture was stirred for 4 hours. The mixture was then filtered, dried, calcined, and cooled to obtain the ZnO / graphene composite material.

[0010] Furthermore, after the anhydrous ethanol is mixed with graphene, the pH value of the graphene suspension is adjusted to 2-3 using dilute hydrochloric acid.

[0011] Furthermore, the mixture of silane coupling agent and anhydrous ethanol is added dropwise to the mixture of anhydrous ethanol and graphene at a uniform rate of 15-20 min.

[0012] Furthermore, the ammonia solution is added to the mixture at a rate of 1-3 drops / min.

[0013] The second technical solution adopted by this invention to solve its technical problem is:

[0014] A method for preparing a Zn-hybridized graphene flame-retardant epoxy acrylate coating, the method comprising: dispersing and dissolving acrylamide in acrylic acid, then sequentially dispersing ammonium polyphosphate, the ZnO / graphene composite material prepared by the above-mentioned method, epoxy acrylate, and a photoinitiator therein, uniformly coating the obtained mixture onto a coating carrier, and curing by light to obtain the Zn-hybridized graphene flame-retardant epoxy acrylate coating.

[0015] Furthermore, the mass ratio of acrylamide, acrylic acid, ammonium polyphosphate, ZnO / graphene composite material, epoxy acrylate, and photoinitiator is 1.4~1.6:1.8~2.2:0.5~1.5:0.0025~0.05:6.4~6.6:0.3~0.5.

[0016] Furthermore, the amount of ZnO / graphene composite material added is 0.43%.

[0017] Furthermore, the amount of ammonium polyphosphate added is 13%.

[0018] Furthermore, the initiator is photoinitiator 1173.

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

[0020] A Zn-hybridized graphene flame-retardant epoxy acrylate coating is prepared by the above-mentioned method for preparing Zn-hybridized graphene flame-retardant epoxy acrylate coating.

[0021] Compared with the prior art, this technical solution has the following advantages:

[0022] To improve the flame retardant properties of epoxy acrylate (EA) coatings, this invention synthesizes a ZnO / graphene composite material using an in-situ precipitation method. This ZnO / graphene composite material is then used as a flame retardant in conjunction with EA, followed by photocuring to prepare a Zn-hybridized graphene flame-retardant epoxy acrylate coating. In the ZnO / graphene composite material, ZnO exhibits various crystalline morphologies, including granular, spindle-shaped, hexagonal, and short rod-shaped forms, growing on the graphene surface and between layers. The assembly sites are uniformly dispersed, and the particle size is consistent. Furthermore, the ZnO possesses a large specific surface area, mitigating agglomeration and achieving mutual modification between the two materials. The addition of the ZnO / graphene composite material reduces the UV transmittance of the EA coating, increases the char residue and LOI value, densifies and reduces the pore size of the char residue, and improves thermal stability. This effectively improves the structure and performance of the composite EA coating, broadening its application range. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 FKGO electron microscope image of the microstructure of silanized modified graphene;

[0025] Figure 2 SKGO electron microscope image showing the microstructure of silanized modified graphene;

[0026] Figure 3 Electron micrograph of the HO-ZnO system at 100 °C;

[0027] Figure 4 Electron micrograph of EG-ZnO system at 100 °C.

[0028] Figure 5 Electron micrograph of ET-ZnO system at 100 °C.

[0029] Figure 6 Electron micrograph of the ETHO-ZnO system at 75 °C.

[0030] Figure 7 This is an electron microscope image of F-ZnO.

[0031] Figure 8 This is an electron microscope image of S-ZnO.

[0032] Figure 9 This is an electron microscope image of H1-ZnO.

[0033] Figure 10 This is an electron microscope image of H2-ZnO.

[0034] Figure 11 This is an electron microscope image of H3-ZnO.

[0035] Figure 12 This is an electron microscope image of H4-ZnO.

[0036] Figure 13 Electron micrograph of P-ZnO

[0037] Figure 14 Electron micrograph of the coating of sample 6;

[0038] Figure 15 Electron micrograph of carbon residue in the coating of sample 6 at 500 °C;

[0039] Figure 16 The image shows the carbon residue after thermogravimetric analysis of the coating of sample 6.

[0040] Figure 17 The adsorption isotherm of FKGO;

[0041] Figure 18 The adsorption isotherm of SKGO;

[0042] Figure 19 The adsorption isotherm for large-particle-size ZnO / graphene;

[0043] Figure 20 The adsorption isotherm for small-particle-size ZnO / graphene;

[0044] Figure 21 The adsorption isotherm of ZnO;

[0045] Figure 22 The image shows the FT-IR spectrum of graphene.

[0046] Figure 23 FT-IR plot of SKGO;

[0047] Figure 24 FT-IR plots of P-ZnO and SKGO;

[0048] Figure 25 FT-IR images of the coatings for samples 1-3;

[0049] Figure 26 Here are the FT-IR images of the coatings for samples 4-6;

[0050] Figure 27 FT-IR images of the coatings for samples 7-9;

[0051] Figure 28 FT-IR images of residual carbon in the coating of samples 1-3;

[0052] Figure 29 FT-IR images of residual carbon in the coating of samples 4-6;

[0053] Figure 30 FT-IR images of residual carbon in the coating of samples 7-9;

[0054] Figure 31 XRD patterns of graphene and SKGO;

[0055] Figure 32 XRD patterns of ZnO / graphene prepared with different solvents, where curves 1-4 are ZnO, HO-ZnO, EG-ZnO, and ETHO-ZnO, respectively;

[0056] Figure 33 XRD patterns of the coatings for samples 1-3;

[0057] Figure 34 The XRD patterns of the coatings for samples 4-6 are shown.

[0058] Figure 35 The XRD patterns of the coatings for samples 7-9 are shown.

[0059] Figure 36 XRD patterns of carbon residue from the coating of samples 1-3;

[0060] Figure 37 XRD patterns of carbon residue from the coating of samples 4-6;

[0061] Figure 38 XRD patterns of carbon residue from the coating of samples 7-9;

[0062] Figure 39 The UV transmittance curves are for the coating films of samples 1-9, where curves 1-9 correspond to the coating films of samples 1-9 respectively.

[0063] Figure 40 The carbon residue diagrams for the coatings of samples 1-9 are shown.

[0064] Figure 41 DSC images of the coating formulations for samples 1-3;

[0065] Figure 42 DSC images of the coating formulations for samples 4-6;

[0066] Figure 43 DSC images of the coating formulations for samples 7-9;

[0067] Figure 44 The thermogravimetric mass change curves of the coatings of samples 1-9 are shown in the figure. Curves 1-9 in the figure represent the coatings of samples 1-9, respectively.

[0068] Figure 45 The figure shows the DTG diagrams of the coatings of samples 1-9, where curves 1-9 represent the coatings of samples 1-9 respectively. Detailed Implementation

[0069] 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.

[0070] The reagents and instruments used in the following examples are as follows:

[0071] Single-layer reduced graphene, Hangzhou Hangdan Optoelectronic Technology Co., Ltd. 1173 photoinitiator, anhydrous ethanol, hydrochloric acid, silane coupling agent KH570, zinc acetate, ammonia, acrylic acid, acrylamide, and ammonium polyphosphate were all purchased from Sinopharm Chemical Reagent Co., Ltd., and were all of analytical grade. EA, SKSHU Paint Co., Ltd.; CP213 electronic balance, Ohaus Instruments (Shanghai) Co., Ltd.; KQ-500VDE three-frequency CNC ultrasonic cleaner, Kunshan Ultrasonic Instrument Co., Ltd.; KSL-1200X muffle furnace, Hefei Kejing Materials Technology Co., Ltd.; BSD-1000 portable UV curing machine, Zhuozhou Best Technology Development Co., Ltd.; QHQ paint film pencil scratch hardness tester, Tianjin Yonglida Materials Testing Machine Co., Ltd.; SU8010 scanning electron microscope (SEM), Hitachi, Japan; APAS2460 specific surface area and porosity meter, McMurray Instruments Co., Ltd.; XRD-6100 X-ray diffractometer, Shimadzu Corporation, Japan; TENSOR27 Fourier transform infrared spectrometer, Bruker GmbH, Germany; UV2550 ultraviolet / visible spectrophotometer, Shimadzu Corporation, Japan; SDT650 thermogravimetric analyzer, Waters Corporation, USA.

[0072] Example 1: Preparation of silanized modified graphene

[0073] Take a clean 250 mL Erlenmeyer flask, add 0.25 g of graphene, and measure 150 mL of anhydrous ethanol. First, add a small amount to wet the graphene, then add a small amount and shake thoroughly to disperse the graphene. Finally, pour in the remaining anhydrous ethanol and sonicate for 1 h. Prepare a 60 °C oil bath and adjust the pH of the ultrasonically dispersed graphene suspension to 2-3 using dilute hydrochloric acid. Then transfer it to a clean 500 mL three-necked flask with a magnetic stir bar pre-placed in the oil bath. Adjust the stir bar speed to approximately 10 rad / min. Take a clean separatory funnel and check for leaks. Measure 10 mL of KH570 and 40 mL of anhydrous ethanol into a clean 100 mL beaker, stir, and transfer to the separatory funnel. Adjust the dropping rate appropriately and add it dropwise to the three-necked flask. The entire titration process should be controlled within 20 minutes. The timing was started from the completion of the titration. The entire system was allowed to react fully at 60 °C for 24 h. After the reaction was completed, the three-necked flask was removed, and the mixture was allowed to cool to room temperature before filtration was started. The product was washed with alcohol and water, and the filter cake was dried in an oven at 50 °C for 24 h to obtain silanized modified graphene.

[0074] Process conditions: Silanized graphene prepared at different KH570 dropping rates was denoted as FKGO and SKGO, respectively.

[0075] Example 2: Preparation of ZnO / graphene composite material

[0076] Take a clean 250 mL Erlenmeyer flask and add 0.033 g of the silanized modified graphene prepared above. Measure 133 mL of anhydrous ethanol, add a small amount to wet the silanized modified graphene, then add a small amount and shake thoroughly to disperse the silanized modified graphene. Finally, pour in the remaining anhydrous ethanol and sonicate for 1 h. Prepare a 75℃ oil bath, then transfer the dispersed silanized modified graphene flotation to a clean 500 mL three-necked flask pre-stirred with a magnetic stirrer. Place the flask in the oil bath and adjust the stirrer speed to approximately 10 rad / min. Take a clean separatory funnel and check for leaks. Weigh 0.117 g of zinc acetate and dissolve it in 133 mL of deionized water in a clean 200 mL beaker. After stirring, transfer the solution to the separatory funnel and adjust the dropping rate appropriately. Add the solution dropwise to the three-necked flask for reaction, controlling the entire titration process at 30°C. After approximately 1 minute, add 1.3 mL of ammonia water to the reaction system at a rate of 2 drops per minute. The entire titration process should be controlled within approximately 10 minutes, starting from the time the ammonia water is added. The entire system should be allowed to react fully at 75°C for 4 hours. After the reaction is complete, remove the three-necked flask and allow the mixture to cool to room temperature before filtration. Wash the product with alcohol and water, and dry the filter cake in an oven at 50°C for 24 hours. Calcinate the product at 400°C for 2 hours, taking precautions to avoid burns. After cooling, remove the product to obtain the ZnO / graphene composite material.

[0077] Process conditions: ZnO / graphene composites prepared with different reaction solvents were designated as HO-ZnO, EG-ZnO, ET-ZnO, and ETHO-ZnO, respectively. The reaction solvent for HO-ZnO was water, for EG-ZnO it was ethylene glycol, for ET it was ethanol, and for ETHO-ZnO it was anhydrous ethanol + water. ZnO / graphene composites prepared with different ammonia droplet rates were designated as F-ZnO and S-ZnO, respectively. ZnO / graphene composites prepared with different reaction times were designated as H1-ZnO, H2-ZnO, H3-ZnO, and H4-ZnO, respectively. The ZnO / graphene composite prepared under the following conditions—anhydrous ethanol + water as the reaction solvent, ammonia added dropwise, reaction temperature of 75 ℃, and reaction time of 4 h—was designated as P-ZnO.

[0078] Example 3: Preparation and curing method of epoxy acrylate coating

[0079] Add ingredients according to the formulas in Tables 1 and 2. The order and requirements for adding ingredients are as follows: First, prepare 9 dry and clean 25mL beakers and label them accordingly. Tare and weigh the beaker, then add acrylic acid solution dropwise to 2 g; weigh 1.5 g of acrylamide and add it to the system, stir, and sonicate for 30 min until the acrylamide solid is completely dissolved; weigh the prescribed amount of ammonium polyphosphate and add it to the system, stir evenly with a glass rod, and then place it in an ultrasonic cleaner for ultrasonic vibration for 30 min until the ammonium polyphosphate solid is completely dissolved; weigh the prescribed amount of ZnO / modified graphene and add it to the system, stir, and then sonicate for 15 min until the ZnO / modified graphene is evenly dispersed; tare the small beaker containing part of the prescription by placing it on an analytical balance, take a dry and clean spatula and transfer 6.5 g of EA to the system, stir, and sonicate for 30 min until the system is evenly dispersed and there are no obvious bubbles; finally, tare the small beaker containing part of the prescription by placing it on an analytical balance, take a dry and clean dropper and transfer 0.4 g of 1173 photoinitiator to the system, stir, and then sonicate for 5 min until the system is evenly dispersed and there are no obvious bubbles, thus obtaining the target coating.

[0080] Table 1 ZnO / modified graphene / EA formulation

[0081]

[0082] Table 2 ZnO / Modified Graphene / Ammonium Polyphosphate / EA Formulation

[0083]

[0084] Sample preparation: First, prepare the mold for curing the sample. Then, pour an appropriate amount of coating into the mold. Turn on the UV lamp of the UV curing machine to preheat for 20 seconds. After preheating, the sample can be placed in for curing. The initial curing time is about 15 seconds. Then, demold the sample and place it back in for curing for about 10 seconds to obtain a fully cured sample. The curing time can be adjusted according to the curing situation. The basic principle of curing is complete curing without discoloration.

[0085] Coating preparation: Take a dry, clean, and flat glass plate, rinse it with anhydrous ethanol, and after the glass plate dries, place it horizontally on the experimental table. Use a glass rod to apply the coating to one end of the glass plate, parallel to the short side of the glass plate. The amount applied depends on the size of the glass plate. After applying the coating, use a dry and clean 100 µm wet film preparer to spread the coating evenly to obtain a coating with a thickness of 100 µm. Turn on the UV lamp of the UV curing machine to preheat for 20 seconds. After preheating, place the coating in the machine for curing. The curing time is about 10 seconds. The curing time can be adjusted according to the curing situation. The basic principle of curing is complete curing without discoloration.

[0086] To understand the composition and structure of each sample, scanning electron microscopy (SEM), surface area and porosity analyzer (BET), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), ultraviolet / visible spectrophotometer, and thermogravimetric analyzer (TG) were used to characterize the samples.

[0087] The microstructure, size, and distribution of graphene, modified graphene, and ZnO / graphene samples were observed using a scanning electron microscope (SEM) of model SU8010.

[0088] Experimental Example 1: Microstructure Analysis of Modified Graphene

[0089] Figure 1 and Figure 2 The effect of KH570 dropping rate on graphene modification was investigated. The comparison showed that when the dropping rate was too fast, the coupling effect between KH570 and the surface groups of graphene was poor and the graphene was not dispersed enough. When the dropping rate was slow, the graphene was relatively dispersed and the tendency to agglomerate was reduced, which effectively improved the compatibility between graphene and the matrix.

[0090] Experimental Example 2: Microstructure Analysis of ZnO / Graphene

[0091] (1) Effect of reaction solvent on ZnO morphology

[0092] Figure 3 The image shows an electron microscope image of the HO-ZnO system at 100 °C. The ZnO grows in a three-dimensional cluster-like flower shape on the graphene surface. The growth sites are relatively concentrated and not uniformly dispersed, and the particle size is relatively large, all above 1 µm. Figure 4 The image shows an electron microscope image of EG-ZnO at 100℃. ZnO grows in the form of spherical particles on the surface of graphene and between layers. The particles covered between layers are also clearly visible. The growth sites are relatively dispersed and the particle size is small, around 300 nm. Figure 5 The image shows an electron microscope image of ET-ZnO at 100℃. ZnO particles are dispersed on the graphene surface. The reaction was incomplete due to solvent evaporation, and the fine particles are incompletely grown ZnO. Figure 6 The image shows an electron microscope (EM) image of the ETHO-ZnO system at 75 °C. ZnO grows on the graphene surface and between layers in various morphologies, including spherical, spindle-shaped, hexagonal, and short rod-shaped forms. The growth sites are also very dispersed, and the particle size is relatively small, ranging from 100 to 200 nm. This comparison demonstrates that using anhydrous ethanol and water as the reaction solvent can assemble small-sized and uniformly grown ZnO particles on the graphene surface.

[0093] (2) Effect of ammonia droplet acceleration on ZnO morphology

[0094] Figure 7 and Figure 8The effect of ammonia dripping rate on the morphology of ZnO / graphene was investigated. Comparison revealed that rapid ammonia addition caused ZnO to accumulate and assemble into a three-dimensional cluster-like flower shape on the graphene surface, with a larger particle size of 500-800 nm. In contrast, slowly added ammonia produced spindle-shaped ZnO particles with a more uniform size of 200-300 nm, dispersed on the graphene surface and at growth sites between layers. This indicates that reducing the alkali dripping rate is beneficial for the formation of small-diameter ZnO on the graphene surface.

[0095] (3) Effect of reaction time on ZnO morphology

[0096] Figure 9-12 The effect of different reaction times on the morphology of ZnO / graphene was investigated. The particle size of ZnO was 600-800 nm after 1 h of reaction, 600-800 nm after 2 h, 200-300 nm after 3 h, and 100-200 nm after 4 h. The comparison shows that the particle size of ZnO is inversely proportional to the reaction time; as the reaction time increases, the particle size of ZnO loaded on graphene gradually decreases, reaching a minimum of 100-200 nm after 4 h. Figure 13 The image shows an electron microscope image of ZnO / graphene after the reaction conditions were optimized. The above investigation revealed that the optimal reaction conditions were anhydrous ethanol + water as the solvent, dropwise addition of alkali, a reaction temperature of 75 ℃, and a reaction time of 4 h. The optimized ZnO grew on the graphene surface and between layers in various crystalline morphologies, including granules, spindles, hexagons, and short rods. The assembly sites were evenly dispersed, and the particle size was uniform between 100-200 nm, which met the expected target.

[0097] Experimental Example 3: Microstructure Analysis of Coating

[0098] Figure 14 The image shows an electron microscope (EMS) image of the coating of sample 6. Under the EMS, it can be seen that most of the ZnO / graphene added as a flame retardant is encapsulated by the polymer, while a small portion of graphene can still be observed, indicating that the ZnO / graphene is relatively uniformly dispersed in the EA formulation system.

[0099] Experimental Example 4: Microscopic Morphology Analysis of Residual Carbon in Coating

[0100] Figure 15The images show electron micrographs of the char residue from the coating of Sample 6 at 500 °C. Figures a and b show the outer surface morphology of the char residue from Sample 6 at 500 °C. The white particles observed on the outer surface are ZnO particles remaining after combustion. Enlarged gas chambers are also visible, some of which ruptured at 500 °C. Figures c, d, e, and f show the internal morphology of the char residue from Sample 6 at 500 °C. Numerous gas chambers of varying sizes, ranging from tens to hundreds of micrometers in pore size, are observed after combustion. The addition of graphene helps form an interpenetrating network structure inside the coating after combustion. The tortuous channels effectively block the penetration of heat and oxygen, improving the flame-retardant properties of the EA coating.

[0101] Experimental Example 5: Microstructure Analysis of Coating After Thermogravimetric Analysis

[0102] Figure 16 The image shows an electron microscope (EM) image of the carbon residue after thermogravimetric analysis of the coating of sample 6. Under the EM, it can be observed that the coating completely burns after being heated to 800 ℃, generating more gas than when it burns in a muffle furnace at 500 ℃. The generation of a large amount of gas causes all the gas chambers formed by combustion to rupture, forming pores. Pores of different sizes can be observed on the surface of the carbon residue, with pore diameters ranging from tens to hundreds of nanometers.

[0103] The specific surface area of ​​graphene, modified graphene, and ZnO / graphene was determined using an APAS2460 specific surface area and porosity meter.

[0104] Experimental Example 6: Specific Surface Area Analysis of Modified Graphene

[0105] Figure 17 and Figure 18 These are adsorption isotherms of graphene modified with different KH570 dropping rates. Measurements show that the BET specific surface area of ​​FKGO is 263.0370 m² / g, while that of SKGO is 264.9678 m² / g, slightly higher than the former.

[0106] Figure 19 and Figure 20 These are adsorption isotherms for ZnO / graphene with different particle sizes. Figure 21 This is the adsorption isotherm of ZnO. Measurements show that the BET specific surface area of ​​large-particle ZnO / graphene is 72.7630 m² / g, the BET specific surface area of ​​small-particle ZnO / graphene is 150.3156 m² / g, and the BET specific surface area of ​​ZnO itself is 30.8766 m² / g. Figure 18The modified graphene has a BET specific surface area of ​​264.9678 m² / g. This indicates that assembling ZnO onto the graphene surface causes a slight decrease in the BET specific surface area of ​​the ZnO / graphene ratio compared to graphene alone, but the final BET specific surface area falls between that of ZnO and graphene. Comparatively, smaller ZnO particle sizes loaded on graphene result in a larger measured BET specific surface area for the ZnO / graphene ratio, indicating better performance.

[0107] A TENSOR27 Fourier transform infrared spectrometer was used in the wavenumber range of 250-4000 cm⁻¹. -1 Infrared absorption spectra and functional group analysis were performed on samples such as graphene, modified graphene, and ZnO / graphene.

[0108] Experimental Example 6: Infrared Analysis of Modified Graphene

[0109] Figure 22 This is the FT-IR spectrum of graphene, showing three characteristic peaks of graphene, located at 1750 cm⁻¹. -1 1560cm -1 1192cm -1 At each location, the corresponding peaks are the characteristic absorption peaks of C=O, C=C, and CO bonds in graphene. Figure 23 The FT-IR spectrum of SKGO shows two new peaks compared to graphene, at 1065 cm⁻¹. -1 Si-OC bond at 779 cm -1 The characteristic absorption peaks of the Si-C bonds at the point indicate that KH570 was used to modify the graphene.

[0110] Experimental Example 7: Infrared Analysis of ZnO / Graphene

[0111] Figure 24 The figures show the FT-IR spectra of P-ZnO and SKGO, with curves 1 and 2 representing P-ZnO and SKGO, respectively. The comparison shows that loading ZnO onto graphene does not cause the disappearance of graphene characteristic peaks; the peak at 1733 cm⁻¹ remains intact. -1 1570 cm -1 1220cm -1 Each peak corresponds to a characteristic absorption peak of the C=O double bond, C=C double bond, and CO single bond in graphene.

[10] At 490 cm -1 The peak at this point is a characteristic absorption peak of the Zn-O bond, which fully indicates that the graphene has been loaded with ZnO.

[0112] Experimental Example 8: Infrared Analysis of Coating

[0113] Figure 25-27The figure shows the FT-IR spectra of the formulation coatings, with curves 1-9 representing the formulation coatings of samples 1-9, respectively. As can be seen from the figure, at 1720 cm⁻¹... -1 1600 cm -1 1238 cm -1 Each peak corresponds to a characteristic absorption peak of the C=O, C=C, and CO bonds.

[10] ; at 473 cm -1 The peak at this location is a characteristic absorption peak of ZnO.

[0114] Experimental Example 9: Infrared Analysis of Residual Carbon in Coatings

[0115] Figures 28-30 The figure shows the FT-IR spectra of the char residue of the coating, with curves 1-9 representing the char residue of the coating at 500℃ for samples 1-9, respectively. As can be seen from the figure, the char residue of the coating after calcination in a muffle furnace at 500℃ has a char content of approximately 1700 cm⁻¹. -1 1610 cm -1 1242 cm -1 The intensity of the C=O, C=C, and CO characteristic peaks of graphene at 464 cm⁻¹ decreased compared to before combustion; -1 The characteristic absorption peak of ZnO is still present at that location.

[0116] The crystal structure, texture and stress of graphene, modified graphene, ZnO / graphene and other samples were measured using an XRD-6100X X-ray diffractometer within an angle range of 10-80°.

[0117] Experimental Example 9: XRD Analysis of Modified Graphene

[0118] Figure 31 The figures show the XRD patterns of graphene and SKGO, with curve 1 representing the original graphene and curve 2 representing SKGO. As can be seen from the figures, the diffraction peaks of the graphene before and after modification are at the same positions, appearing at diffraction angles of 2θ = 23.2° and 2θ = 43.4°, corresponding to the (002) and (100) crystal planes of graphene, respectively. Furthermore, the diffraction peaks of the modified graphene are higher, possibly due to the introduction of new substances onto the surface of the modified graphene.

[0119] Experimental Example 10: XRD Analysis of ZnO / Graphene

[0120] Figure 32XRD patterns of ZnO / graphene prepared with different solvents are shown. Curves 1-4 in the figure are ZnO, HO-ZnO, EG-ZnO, and ETHO-ZnO, respectively. As can be seen from the figure, ZnO, HO-ZnO, EG-ZnO, and ETHO-ZnO all have characteristic peaks at 2θ=31.8°, 2θ=34.4°, 2θ=36.3°, 2θ=47.5°, 2θ=56.6°, 2θ=63.1°, 2θ=66.4°, 2θ=67.9°, and 2θ=69.1°, which correspond to the (100), (002), (101), (102), (110), (103), (200), (112), and (201) crystal planes of ZnO, respectively, proving that ZnO prepared with anhydrous ethanol + water as solvent belongs to the hexagonal wurtzite type.

[0121] Experimental Example 11: Coating XRD Analysis

[0122] Figure 33-35 The XRD patterns of the coatings for samples 1-9 are shown. As can be seen from the figures, all coatings for samples 1-9 exhibit a polymer peak at 2θ=17°, while the characteristic peak of graphene was not observed. The peak heights of the coatings for samples 1-6 at 2θ=17° are essentially consistent and do not change with the amount of ZnO / graphene added. The peak heights of the coatings for samples 7-9 at 2θ=17° decrease with increasing ammonium polyphosphate content, showing an inverse relationship with the amount of ammonium polyphosphate added.

[0123] Experimental Example 12: XRD Analysis of Residual Carbon in Coatings

[0124] Figures 36-38 The XRD patterns of the carbon residue from the coatings of samples 1-9 at 500 °C are shown. As can be seen from the figures, all carbon residues from the coatings of samples 1-9 at 500 °C exhibit a polymer peak at 2θ=17°. Due to the proximity of the polymer peak and the characteristic peak of the graphene peak, they influence each other, causing a shift in the graphene peak position and a decrease in intensity. The shifted graphene peak is located at 2θ=25.5°. Furthermore, the peak heights of the diffraction peaks at 2θ=17° and 2θ=25.5° in the carbon residues of the coatings of samples 1-9 at 500 °C gradually decrease.

[0125] Example 13: The transmittance of the coating was measured using a UV2550 UV / Vis spectrophotometer in the wavelength range of 200-800 nm.

[0126] Figure 39The figures show the UV transmittance curves of the coating films for samples 1-9, with curves 1-9 corresponding to the coating films for samples 1-9, respectively. As can be seen from the figure, in the 200-300 nm UV region, the transmittance of the coating film first decreases and then increases, eventually approaching 0; in the 300-400 nm near-UV region, the transmittance of the coating film increases at the fastest rate; the transmittance of the coating films for samples 1-6 in the 400-800 nm visible region is inversely proportional to the amount of ZnO / graphene added, decreasing from 86% to 73%; the transmittance of the coating films for samples 7-9 in the 400-800 nm visible region is inversely proportional to the amount of ammonium polyphosphate added, decreasing from 69% to 57%.

[0127] Test Example 14: The hardness of the sample was tested using a QHQ pencil scratch hardness tester according to the national standard GB 6739-86.

[0128] Table 3 Coating Hardness Test Results

[0129]

[0130] As shown in Table 3, the hardness of the ZnO / graphene coating does not change with the amount of ZnO / graphene and ammonium polyphosphate. The hardness of the coatings of samples 1-9 is HB.

[0131] Test Example 14: Water Absorption Rate Test

[0132] After drying the coating film, weigh it and record the weight as m1 (g). After soaking it in water for 24 hours, weigh it quickly and record the weight as m2 (g). The formula for calculating the water absorption rate is:

[0133]

[0134] Table 4. Results of Coating Water Absorption Test

[0135]

[0136] Table 4 shows the water absorption test results of the coating formulations of samples 1-9. Comparing the water absorption rates of the coating formulations of samples 1-6, it can be seen that as the amount of ZnO / graphene added increases, the water absorption of the coating first decreases and then increases. This is because the ZnO / graphene composite material has a certain barrier effect on water. However, the greater the amount of ZnO / graphene added, the easier it is to agglomerate in the EA system, causing local defects and resulting in a larger water absorption rate. The water absorption rate of sample 4 is the lowest, at 5.08%. Comparing the water absorption rates of the coating formulations of samples 7-9, it can be seen that the water absorption rate of the coating decreases as the amount of ammonium polyphosphate added increases.

[0137] Experimental Example 15: Flame Retardant Performance Analysis

[0138] The samples were tested using a KSL-1200X muffle furnace. The mass of the empty crucible was recorded as m1 (g), and the mass after placing the sample in was recorded as m2 (g). The crucible was heated to 500℃ in the muffle furnace at a rate of 10℃ / min, immediately removed, cooled, and then weighed (recorded as m3 (g)). The formula for calculating the char residue rate is:

[0139]

[0140] Figure 40 To determine the morphology of the char residue generated after drying the coating, it was placed in a muffle furnace with a heating rate of 10 °C / min and calcined immediately at 500 °C. Comparison shows that with increasing amounts of ZnO / graphene and ammonium polyphosphate in the formulation, the expansion ratio of the char residue at 500 °C gradually increased, the char residue became more intact, and the pores inside the char residue gradually changed from large pores to dense small pores.

[0141] Table 5. Test results of flame retardant performance of coating

[0142]

[0143] Table 5 shows that the char residue of the coatings in samples 1-6 increases with the increase of ZnO / graphene addition, while the char residue of the coatings in samples 7-9 increases with the increase of ammonium polyphosphate addition, with sample 9 having the highest char residue at 36.18%. The LOI value of the coatings in samples 1-6 increases with the increase of ZnO / graphene addition, while the LOI value of the coatings in samples 7-9 increases with the increase of ammonium polyphosphate addition, with sample 9 having the highest LOI value at 38. With the increase of ZnO / graphene and ammonium polyphosphate addition, the vertical flammability rating of the coatings in samples 1-9 changes from No to V-0, showing a significant improvement in flame retardant performance compared to EA. Comparing samples 6 and 7, it can be seen that the addition of ammonium polyphosphate significantly improves the char residue of the coating, and the flame retardant effect of ammonium polyphosphate is better than that of ZnO / graphene. The higher the char residue rate, the higher the LOI value, and the better the flame retardant performance of the coating. As shown in the table, the coating of sample 9 has the best flame retardant performance, with a char residue rate of 36.18%, an LOI value of 38, and a vertical burning rating of V-0.

[0144] Experimental Example 16: DSC Analysis

[0145] Figures 41-43The figures show the DSC patterns of the coatings of samples 1-9, heated to 800 °C at a rate of 10 °C / min. The figures indicate that during the heating process, the endothermic peak temperatures of the coatings of samples 1-9 were 363.2 °C, 365.8 °C, 367.7 °C, 369.5 °C, 371.3 °C, 373.1 °C, 357.7 °C, 355.1 °C, and 351.5 °C, respectively, while the exothermic peak temperatures were 429.5 °C, 431.3 °C, 432.4 °C, 434.9 °C, 438.6 °C, 441.5 °C, 463.2 °C, 467.8 °C, and 473.3 °C, respectively. Comparing the coating formulations of samples 1-6, it can be seen that the endothermic and exothermic temperatures of the coating increase with the increase of ZnO / graphene addition. This may be because graphene and the ZnO particles loaded on it promote the formation of a more stable carbon layer in the coating, effectively improving the thermal stability of the coating. Comparing the coating formulations of samples 7-9, it can be seen that with the addition of ammonium polyphosphate, the endothermic peak temperature of the coating decreases and the exothermic peak temperature increases. This may be because ammonium polyphosphate decomposes first upon heating to generate new substances that protect the coating, hindering the decomposition of the coating and further improving the thermal stability of the coating.

[0146] Example 17: The sample was tested using a thermogravimetric analyzer of model SDT650.

[0147] Take an appropriate amount of sample powder and put it into a small crucible. Set the heating rate to 10 ℃ / min and the ending temperature to 800 ℃. The changes in the heat release rate and mass of the sample with temperature can be observed.

[0148] Figure 44 The thermogravimetric mass change curves of the coatings for samples 1-9 are shown in the figure. Curves 1-9 represent the coatings for samples 1-9, respectively. The comparison shows that the coating for sample 9 has the best thermal stability and the highest char residue rate of 30.73%. As can be seen from the figure, the thermal degradation process of this ZnO / graphene flame-retardant EA coating can be roughly divided into three stages: the first stage is 0-200 ℃, during which the thermal degradation rate is slow and the mass loss is small; the second stage is 200-450 ℃, during which the thermal degradation rate is extremely fast and the mass loss is large; the third stage is 450-800 ℃, during which the thermal degradation rate and the mass loss rate of the coating decrease. At lower temperatures, the coating performance is relatively stable. As the temperature increases, the internal structure of the coating is destroyed, and the coating begins to degrade rapidly, resulting in severe mass loss. Because the degraded char layer has a certain degree of stability, the thermal degradation and mass loss rates gradually level off after 450 ℃.

[0149] Figure 45The DTG diagrams for the coatings of samples 1-9 are shown. Comparing samples 1-6, it can be seen that with the increase of ZnO / graphene addition, the degradation rate corresponding to the coating reaching the maximum heat release rate decreases, indicating that the addition of ZnO / graphene composite material can improve the flame retardant performance of the coating. Comparing samples 7-9, it can be seen that with the increase of ammonium polyphosphate addition, the temperature corresponding to the coating reaching the maximum heat release rate decreases. This is because as the temperature increases, ammonium polyphosphate first catalyzes the decomposition of the polymer to generate new substances with higher flame retardancy, protecting the polymer from rapid degradation and generating a more stable char layer to hinder coating decomposition. This indicates that the addition of ammonium polyphosphate improves the flame retardant performance of the coating to a greater extent.

[0150] This paper synthesizes ZnO / graphene composite materials using an in-situ precipitation method and adds them as flame retardants to the EA system to improve flame retardant properties, thus broadening their application range. Specific conclusions are as follows:

[0151] (1) Electron microscopy and infrared results show that the addition of KH570 effectively improves the dispersibility of graphene.

[0152] (2) By controlling the reaction conditions, small-particle-size ZnO / graphene composite materials can be synthesized. Electron microscopy and XRD results show that ZnO grows on the surface and between layers of graphene in various crystalline morphologies such as granules, spindles, hexagons, and short rods. The assembly sites are evenly dispersed, the particle size is uniform, between 100-200 nm, the crystallinity is high, and it also has a large specific surface area.

[0153] (3) As the amount of ZnO / graphene composite material added increases, the UV transmittance of the EA coating decreases, the residual carbon content and LOI value of the coating increase, the residual carbon pores become denser and smaller, and the thermal stability becomes better.

[0154] (4) ZnO / graphene composite material can effectively improve the flame retardant performance of EA coating as a flame retardant. When the addition amount of ZnO / graphene composite material and ammonium polyphosphate is 0.43% and 13.0% respectively, the char rate is the highest at 36.18%, the LOI value is 38, the vertical burning level is V-0, and the flame retardant performance of the prepared target coating is the best.

[0155] 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 method for preparing a ZnO / graphene composite material, characterized in that, The method includes: At 60°C, a mixture of silane coupling agent and anhydrous ethanol was added dropwise to a mixture of anhydrous ethanol and graphene and stirred for 24 hours. The mixture was then filtered and dried to obtain silanized modified graphene. At 75°C, zinc acetate solution was added dropwise to a mixture of anhydrous ethanol and silanized modified graphene to obtain a mixed solution. Ammonia water was then added dropwise to the mixed solution, and the mixture was stirred for 4 hours. The mixture was then filtered, dried, calcined, and cooled to obtain the ZnO / graphene composite material.

2. The method for preparing the ZnO / graphene composite material according to claim 1, characterized in that: The anhydrous ethanol was mixed with graphene, and the pH of the graphene suspension was adjusted to 2-3 using dilute hydrochloric acid.

3. The method for preparing the ZnO / graphene composite material according to claim 1, characterized in that: The mixture of silane coupling agent and anhydrous ethanol is added dropwise to the mixture of anhydrous ethanol and graphene at a uniform rate of 15-20 min.

4. The method for preparing the ZnO / graphene composite material according to claim 1, characterized in that: The ammonia solution is added to the mixture at a rate of 1-3 drops / min.

5. A method for preparing a Zn-hybridized graphene flame-retardant epoxy acrylate coating, characterized in that, The method includes: dispersing and dissolving acrylamide in acrylic acid, then sequentially dispersing ammonium polyphosphate, the ZnO / graphene composite material prepared by the method of any one of claims 1 to 4, epoxy acrylate, and photoinitiator therein, uniformly coating the prepared mixture onto a coating carrier, and curing by light to obtain a Zn hybrid graphene flame-retardant epoxy acrylate coating.

6. The method for preparing the Zn hybrid graphene flame-retardant epoxy acrylate coating according to claim 5, characterized in that: The mass ratio of acrylamide, acrylic acid, ammonium polyphosphate, ZnO / graphene composite material, epoxy acrylate, and photoinitiator is 1.4~1.6:1.8~2.2:0.5~1.5:0.0025~0.05:6.4~6.6:0.3~0.

5.

7. The method for preparing the Zn hybrid graphene flame-retardant epoxy acrylate coating according to claim 5, characterized in that: The ZnO / graphene composite material is added at a rate of 0.43%.

8. The method for preparing the Zn hybrid graphene flame-retardant epoxy acrylate coating according to claim 5, characterized in that: The amount of ammonium polyphosphate added is 13%.

9. The method for preparing the Zn hybrid graphene flame-retardant epoxy acrylate coating according to claim 5, characterized in that: The initiator is photoinitiator 1173.

10. A Zn-hybridized graphene flame-retardant epoxy acrylate coating, characterized in that: The Zn-hybridized graphene flame-retardant epoxy acrylate coating is prepared by the method described in any one of claims 5 to 9.

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