Solid conductive polyurethane-based coating composition and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a solid conductive polyurethane-based coating composition and a preparation method thereof. Comprising the following steps: adding graphite powder into concentrated H2SO4, cooling, adding KMnO4, stirring, heating for reaction, adding deionized water, cooling, adding water and a H2O2 solution, stirring, adding deionized water, stirring, standing, separating supernate, washing, precipitating, filtering and drying to obtain graphene oxide; thermally reducing the graphene oxide to obtain thermally reduced graphene oxide; dispersing the thermally reduced graphene oxide in a polyvinyl alcohol solution to obtain modified graphene; adding the modified graphene and the modified cardanol into waterborne polyurethane, stirring, performing ultrasonic treatment, baking and cooling to obtain the solid conductive polyurethane-based coating composition. The solid conductive coating solves the problems of dispersion difficulty, coating embrittlement, low toughness, impact resistance and the like of the solid conductive coating.

Description

Technical Field

[0001] This application relates to the field of coating technology, specifically to a solid conductive polyurethane-based coating composition and its preparation method. Background Technology

[0002] Conductive coatings, as a type of special functional material that combines conductivity with the film-forming properties of traditional coatings, represent a significant achievement of the cross-integration of modern materials science and coating technology. Their development is deeply intertwined with technological innovations in fields such as electronics, new energy, and aerospace. Conductive coatings have undergone nearly eighty years of technological evolution, evolving from early single-filler conductive systems to a diversified approach combining various fillers, including metal powders, carbon-based materials, and conductive polymers, with different film-forming resins. After decades of technological accumulation, they have been widely deployed in military and civilian fields such as electronic component packaging, electromagnetic shielding, antistatic coating, and printed circuits, becoming one of the key materials supporting the high-quality development of related industries.

[0003] However, solid conductive coatings still face many key bottlenecks in the process of technological industrialization, which seriously restrict their application scope and performance: First, poor dispersion stability. Conductive fillers (such as graphene, carbon nanotubes, and metal powders) usually have high specific surface areas and strong intermolecular forces, making them prone to agglomeration and sedimentation in solid resin systems. This makes it difficult to form a uniform and continuous conductive network, resulting not only in large fluctuations in the conductivity of the coating and low conductivity efficiency, but also affecting the smoothness and consistency of the coating appearance. Second, imbalance in the mechanical properties of the coating. To ensure conductivity, a certain amount of conductive filler needs to be added. However, the introduction of a high proportion of filler often disrupts the continuous phase structure of the film-forming resin, leading to stress concentration inside the coating and problems such as brittleness and insufficient toughness. This manifests as the coating being prone to cracking and peeling when subjected to slight external impact, bending, or thermal cycling, making it unable to meet the needs of use under complex working conditions. Third, insufficient impact resistance. Traditional solid conductive coatings are mostly made of rigid resins, which have poor interfacial compatibility with conductive fillers and weak interfacial bonding. When subjected to external impact loads, stress cannot be effectively transferred and dispersed, and the coating is prone to local damage, thereby losing its conductive and protective functions.

[0004] Therefore, developing a solid conductive coating that combines good dispersion stability, excellent electrical conductivity, and outstanding mechanical properties (high toughness and strong impact resistance) has become an urgent problem to be solved in the field of coating technology, and is of great significance for promoting the technological upgrading and green development of related industries. Summary of the Invention

[0005] To address the aforementioned problems, this application provides a solid conductive polyurethane-based coating composition and its preparation method, thereby solving the problems of difficult dispersion, brittle coating, low toughness, and poor impact resistance in solid conductive coatings.

[0006] To achieve the above objectives, this application provides a method for preparing a solid conductive polyurethane-based coating composition, comprising the following steps: S1. Add graphite powder to concentrated H2SO4, cool and then add KMnO4, stir and heat to react, then add deionized water, cool and add water and H2O2 solution, stir, add deionized water, stir, let stand, separate the supernatant, wash the precipitate, filter and dry to obtain graphene oxide. In the above process, a strong acid oxidation method is used to intercalate and oxidize graphite. Concentrated H2SO4 is used as an acidic medium and dehydrating agent to destroy the interlayer forces of graphite. KMnO4 is used as a strong oxidizing agent to oxidize the C atoms in graphite and introduce oxygen-containing functional groups such as hydroxyl, epoxy, and carboxyl groups, causing the graphite sheets to expand and peel off to form graphene oxide. Subsequently, H2O2 is used to reduce excess KMnO4 and terminate the oxidation reaction.

[0007] S2. Thermally reduce graphene oxide, during which nitrogen gas is introduced to obtain thermally reduced graphene oxide; In the above process, under a nitrogen atmosphere, the high temperature causes the oxygen-containing functional groups in graphene oxide to decompose, restoring the conjugated sp² carbon network structure of graphene, thereby improving conductivity.

[0008] S3. Disperse thermally reduced graphene oxide in a polyvinyl alcohol solution, stir, sonicate, vacuum filter, and wash to obtain modified graphene. In the above process, the water solubility and amphiphilicity of polyvinyl alcohol are utilized to bind with oxygen-containing groups on the surface of thermally reduced graphene oxide through hydrogen bonds or van der Waals forces, thereby improving its hydrophilicity and preventing aggregation. Ultrasonic treatment promotes the exfoliation of thermally reduced graphene oxide into single-layer or few-layer nanosheets. Vacuum filtration removes unbound polyvinyl alcohol, resulting in monodisperse modified graphene.

[0009] S4. Polytetramethylene ether glycol and dibutyltin dilaurate are added to a reaction vessel, then isophorone diisocyanate is added to react, followed by 2,2-dimethylolpropionic acid to continue the reaction, then 1,4-butanediol is added to continue the reaction, the mixture is cooled, triethylamine is added, the mixture is stirred, deionized water is added, and finally diethylenetriamine is added to react to obtain waterborne polyurethane. In the above process, polytetramethylene ether glycol and isophorone diisocyanate react with -OH and -NCO under the action of the catalyst dibutyltin dilaurate to generate a prepolymer. 2,2-dimethylolpropionic acid is added, and its hydroxyl groups react with the -NCO of the prepolymer to introduce carboxyl groups as hydrophilic groups. 1,4-Butanediol is added to react with the remaining -NCO to extend the molecular chain. Then, triethylamine is used to neutralize the carboxyl groups to form ionic hydrophilic groups. Water is added to emulsify and disperse the mixture into an aqueous emulsion. Diethylenetriamine is added to react with the remaining -NCO in the emulsion to further extend the chain, increase the molecular weight, and enhance the density of the coating.

[0010] S5. Modified graphene and modified cashew phenol are added to waterborne polyurethane, stirred, ultrasonically treated, baked, and cooled to obtain a solid conductive polyurethane-based coating composition.

[0011] The method for preparing the modified cashew phenol is as follows: A1: Add 4-5g of cashew phenol and 3-3.2g of glycidol to the reactor, blow nitrogen into the mixture and stir for 20-25min, and carry out the multi-stage heating reaction. After the reaction is completed, cool to 25-28℃ to obtain hyperbranched cashew phenol polyglycerol. In the above reaction process, cashew phenol undergoes a ring-opening reaction with glycidol. The phenolic hydroxyl group of cashew phenol attacks the epoxy group of glycidol to form a COC bond. At the same time, the hydroxyl group of glycidol forms a hydrogen bond with the phenolic hydroxyl group of cashew phenol, ultimately yielding hyperbranched cashew phenol polyglycerol.

[0012] A2: Under a nitrogen atmosphere, add 12-16 mmol of hyperbranched cashew phenol polyglycerol, 12-16 mmol of hyponitrotriacetic acid and 0.01-0.02 g of p-toluenesulfonic acid to the reactor, react at 85-90℃ for 3-5 h, and then rotary evaporate to obtain modified cashew phenol.

[0013] In the above reaction process, hyperbranched cashew polyglycerol and hypotriacetic acid undergo esterification under the catalysis of p-toluenesulfonic acid to form ester bonds -COO-, introducing hypotriacetic acid into the molecular chain of hyperbranched cashew polyglycerol to obtain modified cashew phenol.

[0014] Furthermore, the mass-to-volume ratio of graphite powder, concentrated H2SO4, and KMnO4 in step S1 is 2-4g: 65-75ml: 9-11g.

[0015] Furthermore, the H2O2 solution mentioned in step S1 has a concentration of 25-30%, and the mass-to-volume ratio of H2O2 solution to KMnO4 is 25-35 ml: 9-11 g.

[0016] Furthermore, the precipitate in step S1 is washed 2-3 times with 5-6% HCl.

[0017] Furthermore, the thermal reduction in step S2 is carried out at a temperature of 1000-1200℃ for 1-2 minutes.

[0018] Furthermore, the polyvinyl alcohol solution mentioned in step S3 has a concentration of 1-2 wt%, and the mass-to-volume ratio of the polyvinyl alcohol solution to the thermally reduced graphene oxide is 450-500 ml: 1 g.

[0019] Furthermore, in step S3, the ultrasonic treatment has an ultrasonic frequency of 20-30 kHz and an ultrasonic time of 30-40 min.

[0020] Furthermore, in step S4, the mass-to-volume ratio of polytetramethylene ether diol, dibutyltin dilaurate, and isophorone diisocyanate is 30-35g: 0.015-0.02ml: 20-22ml.

[0021] Furthermore, in step S4, the mass-to-volume ratio of 2,2-dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate is 5-6 g: 0.3-0.4 g: 20-22 ml.

[0022] Furthermore, the mass ratio of triethylamine to 2,2-dimethylolpropionic acid in step S4 is 0.3-0.4:5-6.

[0023] Furthermore, in step S4, the mass-to-volume ratio of diethylenetriamine to isophorone diisocyanate is 1.1-1.3 g: 20-22 ml.

[0024] Furthermore, in step S5, the amount of modified graphene added is 2-3% of the mass of the waterborne polyurethane; and the amount of modified cashew phenol added is 2-4% of the mass of the waterborne polyurethane.

[0025] Furthermore, in step S5, the ultrasonic treatment has an ultrasonic frequency of 20-30 kHz and an ultrasonic time of 30-40 min.

[0026] Furthermore, the baking process described in step S5 is carried out at a temperature of 70-80°C for 2-3 hours.

[0027] Furthermore, the multi-stage heating described in step A1 involves reacting at 75-85℃ for 2-2.5 hours, then increasing the temperature at 10℃ / min to 90-100℃ for 4-5 hours, and finally increasing the temperature at 10℃ / min to 110-120℃ for 2-4 hours.

[0028] This application also provides a method for preparing a solid conductive polyurethane-based coating composition, which yields the solid conductive polyurethane-based coating composition.

[0029] In summary, this application has the following beneficial effects: This application presents a solid conductive polyurethane-based coating composition. Through controlled oxidation, graphene oxide with a high specific surface area and abundant oxygen-containing functional groups is obtained, providing a foundation for subsequent exfoliation and thermal reduction. After washing and drying, the composition exhibits high purity, facilitating subsequent processing. Rapid and efficient reduction of graphene oxide preserves its complete sp² structure, resulting in superior conductivity compared to graphene oxide. Temperature and time control remove most oxygen-containing groups, enabling subsequent bonding between polyvinyl alcohol and the oxygen-containing groups on the thermally reduced graphene oxide surface. The modified graphene obtained through polyvinyl alcohol modification increases its dispersibility in aqueous systems, prevents agglomeration, enhances compatibility with aqueous polyurethane, and improves conductivity. Its two-dimensional layered structure can serve as a nano-reinforcing phase dispersed within the aqueous polyurethane matrix, sharing matrix stress by bearing external loads and preventing cracking. By expanding and reducing brittleness, graphene sheets can bend, slip, and wrinkle under stress, absorbing energy and delaying crack propagation, similar to a bridging effect, further improving toughness and impact resistance. Modified cashew nut shells, through their hyperbranched structure and long-chain alkyl groups, can form hydrogen bonds or van der Waals forces with the soft segments of waterborne polyurethane at one end, while the long-chain alkyl groups at the other end can enhance compatibility with waterborne polyurethane, preventing the modified graphene from agglomerating due to polarity differences. Modified cashew nut shells, by introducing carboxyl groups, can form hydrogen bonds with modified graphene and waterborne polyurethane, further improving the dispersibility of modified graphene. The long-chain alkyl groups of modified cashew nut shells enhance the flexibility of waterborne polyurethane. Combining the high conductivity and high dispersibility of modified graphene, the high compatibility of modified cashew nut shells with waterborne polyurethane, and the film-forming properties of waterborne polyurethane, a solid, flexible, and conductive coating is obtained. Detailed Implementation

[0030] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0031] The raw materials involved in the specific embodiments of this application are analytical grade. Additionally: the graphite powder has a purity of 99%, the concentrated H2SO4 concentration is 98%, the KMnO4 purity is 99%, the polyvinyl alcohol molecular weight is 145,000, the polytetramethylene ether glycol molecular weight is 1,000, and the isophorone diisocyanate purity is 98%.

[0032] Example 1 A method for preparing a solid conductive polyurethane-based coating composition includes the following steps: S1. Add 4g of graphite powder to 130ml of concentrated H2SO4, cool to 25℃, add 18g of KMnO4, stir (100rpm) and heat to 40℃ for 2h, then add 240ml of deionized water, cool to 25℃, add 400ml of water and 70ml of 25% H2O2, stir (100rpm) for 30min, then add 1.2L of deionized water, continue stirring for 10min, let stand for 10h, separate the supernatant, wash the precipitate 3 times with 5% HCl, vacuum filter (vacuum degree -0.08MPa, filter membrane pore size 5μm), and dry at 60℃ for 48h to obtain graphene oxide; S2. Take 5g of graphene oxide and place it in a sealed quartz tube. Place the quartz tube in a horizontal furnace preheated to 1000℃ for 2 minutes, during which nitrogen gas is continuously passed through. Remove it and cool it to 25℃ to obtain thermally reduced graphene oxide. S3. Disperse 1g of thermally reduced graphene oxide in 500ml of 2% polyvinyl alcohol solution, stir (200rpm) for 30min, sonicate (20kHz, 30min), vacuum filter (0.08MPa, 5μm pore size), and wash three times with purified water to obtain modified graphene. S4. Add 35g of polytetramethylene ether glycol and 0.02ml of dibutyltin dilaurate to a reaction vessel, add 22ml of isophorone diisocyanate, stir at 80℃ (250rpm) for 2h, add 6g of 2,2-dimethylolpropionic acid, continue stirring at 80℃ for 3h, add 0.4g of 1,4-butanediol, continue stirring at 80℃ for 1h, cool to 30℃, add 0.4g of triethylamine and continue stirring for 15min, add 210ml of deionized water, and finally add 1.3g of diethylenetriamine, react for 1h to obtain waterborne polyurethane; S5. Add 2% modified graphene and 2% modified cashew phenol to waterborne polyurethane, mechanically stir (200 rpm) for 1 hour, then ultrasonically treat (ultrasonic frequency 20 kHz, ultrasonic time 30 min), bake at 80℃ for 2 hours, and cool to 25℃ to obtain a solid conductive polyurethane-based coating composition.

[0033] The method for preparing the modified cashew phenol is as follows: A1: Add 4g of cashew phenol and 3g of glycidol to the reactor, blow nitrogen into the mixture and stir evenly (120 rpm) for 20 min to remove air, react at 75℃ for 2 h, then increase the temperature to 90℃ at 10℃ / min and react for 4 h, and finally increase the temperature to 110℃ at 10℃ / min and react for 2 h. After the reaction is completed, cool to 25℃ to obtain hyperbranched cashew phenol polyglycerol. A2: Under a nitrogen atmosphere, 12 mmol of hyperbranched cashew phenol polyglycerol, 12 mmol of hyponitrotriacetic acid and 0.01 g of p-toluenesulfonic acid were added to the reactor and reacted at 85 °C for 3 h. After the reaction was completed, the mixture was rotary evaporated to obtain modified cashew phenol.

[0034] Example 2 A method for preparing a solid conductive polyurethane-based coating composition includes the following steps: S1. Add 6g of graphite powder to 140ml of concentrated H2SO4, cool to 25℃, add 20g of KMnO4, stir (100rpm) and heat to 40℃ for 2h, then add 240ml of deionized water, cool to 25℃, add 400ml of water and 60ml of 30% H2O2, stir (100rpm) for 30min, then add 1.2L of deionized water, continue stirring for 10min, let stand for 10h, separate the supernatant, wash the precipitate 3 times with 5% HCl, vacuum filter (vacuum degree -0.08MPa, filter membrane pore size 5μm), and dry at 60℃ for 48h to obtain graphene oxide; S2. Take 5g of graphene oxide and place it in a sealed quartz tube. Place the quartz tube in a horizontal furnace preheated to 1100℃ for 1 minute for thermal reduction. During this period, nitrogen gas is continuously introduced. Remove the tube and cool it to 25℃ to obtain thermally reduced graphene oxide. S3. Disperse 1g of thermally reduced graphene oxide in 500ml of 1% polyvinyl alcohol solution, stir (200rpm) for 30min, sonicate (20kHz, 30min), vacuum filter (0.08MPa, 5μm pore size), and wash three times with purified water to obtain modified graphene. S4. Add 35g of polytetramethylene ether glycol and 0.02ml of dibutyltin dilaurate to a reaction vessel, add 22ml of isophorone diisocyanate, stir at 80℃ (250rpm) for 2h, add 6g of 2,2-dimethylolpropionic acid, continue stirring at 80℃ for 3h, add 0.4g of 1,4-butanediol, continue stirring at 80℃ for 1h, cool to 30℃, add 0.4g of triethylamine and continue stirring for 15min, add 210ml of deionized water, and finally add 1.3g of diethylenetriamine, react for 1h to obtain waterborne polyurethane; S5. Add 2.5% modified graphene and 3% modified cashew phenol to waterborne polyurethane, mechanically stir (200 rpm) for 1 hour, then ultrasonically treat (ultrasonic frequency 20 kHz, ultrasonic time 30 min), bake at 80℃ for 2 hours, and cool to 25℃ to obtain a solid conductive polyurethane-based coating composition.

[0035] The method for preparing the modified cashew phenol is as follows: A1: Add 4.5g of cashew phenol and 3.1g of glycidol to the reactor, blow nitrogen into the mixture and stir evenly (120rpm) for 20min to remove air, react at 80℃ for 2h, then increase the temperature to 95℃ at 10℃ / min and react for 4h, and finally increase the temperature to 115℃ at 10℃ / min and react for 2h. After the reaction is completed, cool to 25℃ to obtain hyperbranched cashew phenol polyglycerol; A2: Under a nitrogen atmosphere, 14 mmol of hyperbranched cashew phenol polyglycerol, 14 mmol of hyponitrotriacetic acid and 0.01 g of p-toluenesulfonic acid were added to the reactor and reacted at 85 °C for 3 h. After the reaction was completed, the mixture was rotary evaporated to obtain modified cashew phenol.

[0036] Example 3 A method for preparing a solid conductive polyurethane-based coating composition includes the following steps: S1. Add 6g of graphite powder to 140ml of concentrated H2SO4, cool to 25℃, add 20g of KMnO4, stir (100rpm) and heat to 40℃ for 2h, then add 240ml of deionized water, cool to 25℃, add 400ml of water and 60ml of 30% H2O2, stir (100rpm) for 30min, then add 1.2L of deionized water, continue stirring for 10min, let stand for 10h, separate the supernatant, wash the precipitate 3 times with 5% HCl, vacuum filter (vacuum degree -0.08MPa, filter membrane pore size 5μm), and dry at 60℃ for 48h to obtain graphene oxide; S2. Take 5g of graphene oxide and place it in a sealed quartz tube. Place the quartz tube in a horizontal furnace preheated to 1200℃ for 1 minute for thermal reduction, during which nitrogen gas is continuously introduced. Remove and cool to 25℃ to obtain thermally reduced graphene oxide. S3. Disperse 1g of thermally reduced graphene oxide in 500ml of 1% polyvinyl alcohol solution, stir (200rpm) for 30min, sonicate (20kHz, 30min), vacuum filter (0.08MPa, 5μm pore size), and wash three times with purified water to obtain modified graphene. S4. Add 35g of polytetramethylene ether glycol and 0.02ml of dibutyltin dilaurate to a reaction vessel, add 22ml of isophorone diisocyanate, stir at 80℃ (250rpm) for 2h, add 6g of 2,2-dimethylolpropionic acid, continue stirring at 80℃ for 3h, add 0.4g of 1,4-butanediol, continue stirring at 80℃ for 1h, cool to 30℃, add 0.4g of triethylamine and continue stirring for 15min, add 210ml of deionized water, and finally add 1.3g of diethylenetriamine, react for 1h to obtain waterborne polyurethane; S5. Add 3% modified graphene and 4% modified cashew phenol to waterborne polyurethane, mechanically stir (200 rpm) for 1 hour, then ultrasonically treat (ultrasonic frequency 20 kHz, ultrasonic time 30 min), bake at 80℃ for 2 hours, and cool to 25℃ to obtain a solid conductive polyurethane-based coating composition.

[0037] The method for preparing the modified cashew phenol is as follows: A1: Add 5g of cashew phenol and 3.2g of glycidol to the reactor, blow nitrogen into the mixture and stir evenly (120rpm) for 20min to remove air, react at 85℃ for 2h, then increase the temperature to 100℃ at 10℃ / min and react for 4h, and finally increase the temperature to 120℃ at 10℃ / min and react for 2h. After the reaction is completed, cool to 25℃ to obtain hyperbranched cashew phenol polyglycerol; A2: Under a nitrogen atmosphere, 16 mmol of hyperbranched cashew phenol polyglycerol, 16 mmol of hyponitrotriacetic acid and 0.02 g of p-toluenesulfonic acid were added to the reactor and reacted at 90 °C for 3 h. After the reaction was completed, the mixture was rotary evaporated to obtain modified cashew phenol.

[0038] Comparative Example 1 The difference between this comparative example and Example 3 is that the amount of modified graphene added is 4%.

[0039] Comparative Example 2 The difference between this comparative example and Example 3 is that the thermal reduction temperature is 1300°C.

[0040] Comparative Example 3 The difference between this comparative example and Example 3 is that graphene is used instead of modified graphene.

[0041] Comparative Example 4 The difference between this comparative example and Example 3 is that cashew phenol is used instead of modified cashew phenol.

[0042] Performance testing Functionality tests were performed on the solid conductive polyurethane-based coating compositions prepared in Examples 1-3 and Comparative Examples 1-4.

[0043] Conductivity test: The coating is evenly applied to a clean glass plate. The coating thickness is controlled to be 150μm using a scraping method. After curing, the coating is peeled off from the glass plate and cut into 10×10cm² square samples. The samples are fixed on a four-probe test stage, ensuring that the probes are perpendicular to the coating surface and in close contact. The test current is set to 10mA, and the conductivity is calculated in mS / cm. Impact resistance test: The maximum impact height without damaging the coating was recorded using the GB / T 1732-2020 standard "Test Method for Impact Resistance of Coating Film". The unit is cm. Toughness test: Fix the mold on the glass plate, and use the scraping method to evenly fill the dumbbell-shaped mold with the coating. The mold thickness is 2mm. After curing, peel it off from the mold to obtain a dumbbell-shaped coated sample with a length of 20mm and a width of 4mm. Install the sample on the fixture of the tensile testing machine, ensuring that the fixture is aligned with the sample axis. The tensile speed is 50mm / min, and record the elongation at break. Brittleness test: The coating was uniformly applied to the polycarbonate board to form a 150 μm thick coating. After curing, it was peeled off from the substrate to obtain a rectangular coating sample with a length of 100 mm, a width of 10 mm, and a thickness of 0.1 mm. The sample was fixed on the two support rollers of the bending tester with a loading rate of 1 mm / min. The maximum bending strain without cracking was recorded. The test was repeated 3 times and the average value was taken.

[0044] The test results are shown in Table 1.

[0045] Table 1 Group Conductivity mS / cm Maximum impact height (cm) Elongation at break % Maximum bending strain % Example 1 3.86 43.5 112 5.1 Example 2 4.12 46.7 116 5.3 Example 3 3.75 38.5 105 4.6 Compare with Example 1 2.13 26.8 86 1.7 Compare with Example 2 3.52 24.5 83 1.5 Compare with Example 3 3.43 23.1 80 1.2 Compare with Example 4 3.25 23.8 87 3.5 As shown in Table 1, the solid conductive polyurethane-based coating compositions prepared in the embodiments of this application have excellent electrical conductivity and mechanical properties, exhibiting high electrical conductivity, high impact resistance, high toughness, and low brittleness. Example 2, in particular, demonstrates the best performance. The difference between Comparative Example 1 and Example 3 lies in the addition amount of modified graphene, which is 4%. This high addition amount makes the modified graphene prone to agglomeration, leading to a decrease in mechanical properties and electrical conductivity, resulting in inferior performance compared to Example 3. The difference between Comparative Example 2 and Example 3 lies in the thermal reduction temperature of 1300℃, which leads to excessive reduction and decomposition of oxygen-containing groups. This results in unstable bonding between polyvinyl alcohol and the oxygen-containing groups on the surface of thermally reduced graphene oxide during modification, resulting in poor subsequent dispersibility and reduced electrical and mechanical properties. The test results... The results showed that the conductivity, impact resistance, toughness, and brittleness were all relatively low, which was not as good as in Example 3. The difference between Comparative Example 3 and Example 3 was that graphene was used instead of modified graphene. Graphene has high conductivity, but poor dispersion performance, which resulted in low conductivity and poor mechanical properties of the solid conductive polyurethane-based coating composition prepared in Comparative Example 3. The test results showed that the conductivity, impact resistance, toughness, and brittleness of the solid conductive polyurethane-based coating composition prepared in Comparative Example 3 were not as good as in Example 3. The difference between Comparative Example 4 and Example 3 was that cashew nut shell powder was used instead of modified cashew nut shell powder, which led to changes in compatibility and reduced the dispersion effect of modified graphene, thus reducing the test performance. For example, the test results showed that the conductivity, impact resistance, toughness, and brittleness were all reduced, and the performance was not as good as in Example 3.

[0046] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A method for preparing a solid conductive polyurethane-based coating composition, characterized in that, Includes the following steps: S1. Add graphite powder to concentrated H2SO4, cool and then add KMnO4, stir and heat to react, then add deionized water, cool and add water and H2O2 solution, stir, add deionized water, stir, let stand, separate the supernatant, wash the precipitate, filter and dry to obtain graphene oxide. S2. Thermally reduce graphene oxide, during which nitrogen gas is introduced to obtain thermally reduced graphene oxide; S3. Disperse thermally reduced graphene oxide in a polyvinyl alcohol solution, stir, sonicate, vacuum filter, and wash to obtain modified graphene. S4. Polytetramethylene ether glycol and dibutyltin dilaurate are added to a reaction vessel, then isophorone diisocyanate is added to react, followed by 2,2-dimethylolpropionic acid to continue the reaction, then 1,4-butanediol is added to continue the reaction, the mixture is cooled, triethylamine is added, the mixture is stirred, deionized water is added, and finally diethylenetriamine is added to react to obtain waterborne polyurethane. S5. Modified graphene and modified cashew phenol are added to waterborne polyurethane, stirred, ultrasonically treated, baked, and cooled to obtain a solid conductive polyurethane-based coating composition. The method for preparing the modified cashew phenol is as follows: A1: Add 4-5g of cashew phenol and 3-3.2g of glycidol to the reactor, blow nitrogen into the mixture and stir for 20-25min, and carry out the multi-stage heating reaction. After the reaction is completed, cool to 25-28℃ to obtain hyperbranched cashew phenol polyglycerol. A2: Under a nitrogen atmosphere, add 12-16 mmol of hyperbranched cashew phenol polyglycerol, 12-16 mmol of hyponitrotriacetic acid and 0.01-0.02 g of p-toluenesulfonic acid to the reactor, react at 85-90℃ for 3-5 h, and then rotary evaporate to obtain modified cashew phenol.

2. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The thermal reduction in step S2 is carried out at a temperature of 1000-1200℃ for 1-2 minutes.

3. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The polyvinyl alcohol solution mentioned in step S3 has a concentration of 1-2 wt%, and the mass-to-volume ratio of the polyvinyl alcohol solution to the thermally reduced graphene oxide is 450-500 ml: 1 g.

4. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The mass-to-volume ratio of polytetramethylene ether glycol, dibutyltin dilaurate, and isophorone diisocyanate in step S4 is 30-35g: 0.015-0.02ml: 20-22ml.

5. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The mass-to-volume ratio of 2,2-dimethylolpropionic acid, 1,4-butanediol and isophorone diisocyanate in step S4 is 5-6 g: 0.3-0.4 g: 20-22 ml.

6. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The mass ratio of triethylamine to 2,2-dihydroxymethylpropionic acid in step S4 is 0.3-0.4:5-6.

7. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The mass-to-volume ratio of diethylenetriamine to isophorone diisocyanate in step S4 is 1.1-1.3g: 20-22ml.

8. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The modified graphene mentioned in step S5 is added at an amount of 2-3%; the modified cashew nut shell is added at an amount of 2-4%.

9. The method for preparing a solid conductive polyurethane-based coating composition according to claim 1, characterized in that, The multi-stage heating described in step A1 involves reacting at 75-85℃ for 2-2.5 hours, then increasing the temperature at 10℃ / min to 90-100℃ for 4-5 hours, and finally increasing the temperature at 10℃ / min to 110-120℃ for 2-4 hours.

10. A solid conductive polyurethane-based coating composition, prepared by the preparation method according to any one of claims 1-9.