A graphene-modified antistatic high-gloss powder coating and its preparation method

Abstract

This invention belongs to the field of powder coating technology, specifically relating to a graphene-modified antistatic high-gloss powder coating and its preparation method. This invention aims to solve the problems of insufficient interfacial bonding strength and antistatic durability in existing graphene-modified powder coatings. In this invention, graphene oxide is dispersed and modified using an ionic liquid to obtain modified graphene, which is then blended with branched polyester and extruded to obtain a modified graphene resin. The modified graphene resin is mixed with a matrix resin and heat-treated to obtain a powder coating. After spraying, it undergoes constant-temperature leveling and curing at a higher temperature to obtain the coating product. The coating product prepared by this invention exhibits high interfacial bonding strength, excellent antistatic durability, and good reflectivity and gloss.

Description

Technical Field

[0001] This invention belongs to the field of powder coating technology, specifically relating to a graphene-modified antistatic high-gloss powder coating and its preparation method. Background Technology

[0002] In fields such as electronics and information technology, precision instruments, medical devices, and flammable and explosive chemical environments, powder coatings occupy a crucial position due to their high efficiency, superior performance, environmental friendliness, and cost-effectiveness. In these applications, eliminating static electricity buildup on object surfaces and preventing electrostatic discharge from damaging sensitive electronic components or causing fires and explosions is a core function that coatings must possess. However, with the increasing aesthetic standards of high-end home appliances, automotive interior parts, and consumer electronics products, the market has created an urgent demand for powder coatings that combine excellent conductivity with a mirror-like high gloss and high reflectivity.

[0003] In existing technologies, antistatic powder coatings are mainly prepared through two mechanisms: electronic conductivity and ionic conductivity. Traditional electronic conductivity mechanisms typically involve adding conductive fillers such as carbon black, metal powders, or carbon fibers to the polymer matrix. Building a continuous conductive network often requires a high filler content; however, these fillers typically have high oil absorption, significantly increasing the viscosity of the molten coating and severely hindering resin leveling during curing, leading to defects such as microscopic roughness, orange peel texture, and even pinholes on the coating surface. Ionic conductivity mechanisms involve adding hygroscopic antistatic agents such as quaternary ammonium salts or ionic liquids. While this method causes less damage to the coating's microstructure and helps maintain gloss, its conductivity is heavily dependent on ambient humidity, and the antistatic agent easily migrates to the surface, resulting in short-lasting effects, yellowing at high temperatures, and surface stickiness, making it difficult to achieve permanent antistatic effects. Graphene, as a novel two-dimensional nanomaterial, possesses extremely high conductivity and barrier properties, theoretically making it an ideal material for preparing high-performance antistatic coatings. However, directly adding graphene also faces serious agglomeration problems, and simple physical blending is insufficient to achieve ideal interfacial bonding and leveling performance at low addition levels.

[0004] To address the shortcomings of existing graphene-modified powder coatings in terms of interfacial bonding strength and antistatic durability, a graphene-modified antistatic high-gloss powder coating and its preparation method are proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene-modified antistatic high-gloss powder coating and its preparation method. This invention involves dispersing graphene oxide and modifying it with an ionic liquid to obtain modified graphene, which is then blended with branched polyester and extruded to obtain a modified graphene resin. The modified graphene resin is then mixed with a matrix resin and subjected to heat treatment to obtain a powder coating. After spraying, the coating is subjected to constant-temperature leveling and then cured at a higher temperature to obtain the coating product.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A graphene-modified antistatic high-gloss powder coating and its preparation method, comprising the following steps:

[0008] Unless otherwise specified, the parts in this invention refer to parts by mass.

[0009] Two parts of graphene oxide were added to 400 parts of an ethanol-water solution and ultrasonically dispersed at 400W for 1 hour to obtain a graphene oxide dispersion. The volume fraction of ethanol in the ethanol-water solution was 50%.

[0010] The sheet diameter of graphene oxide is 5-10 μm, the monolayer ratio is >90%, and the oxygen content is >30%.

[0011] One part of ionic liquid was added dropwise to a graphene oxide dispersion. After stirring at 55-70℃ for 2 hours, 0.5 parts of sodium ascorbate were added, and the mixture was refluxed at 80℃ for 4 hours. After the reaction was completed, the mixture was spray-dried at an inlet air temperature of 180℃ and an outlet air temperature of 80℃ to obtain modified graphene.

[0012] The ionic liquid is specifically 1-(2,3-epoxypropyl)-3-methylimidazolium chloride, which is synthesized as follows: 8.2 parts of N-methylimidazolium are dissolved in ethyl acetate under nitrogen protection, and 10.2 parts of epichlorohydrin are added under stirring. The mixture is heated to 80°C and then refluxed and stirred for 36 hours. After cooling, the product is ultrasonically washed with ethyl acetate and then vacuum dried to obtain the ionic liquid.

[0013] Five parts of modified graphene, 0.5 parts of dispersant, and 95 parts of branched polyester were mixed at 40°C and 3000 rpm for 3 minutes, and then extruded. The extrusion process involved four zones: zone 1 at 80°C, zone 2 at 90°C, and zones 3 and 4 at 95°C. The screw speed was set to 400 rpm. After cooling, the extruded sheet was pulverized to D... 50 After reaching a thickness of <5μm, a modified graphene resin is obtained.

[0014] The dispersant is BYK-163; the branched polyester comprises a main chain formed by esterification of 2,2-dimethylolpropionate, with trimethylolpropane as the end group, a weight-average molecular weight of 3000-4000 g / mol, and a hydroxyl value of 470-520 mg KOH / g.

[0015] Mix 50-60 parts of bisphenol A type epoxy resin and 40 parts of carboxylated polyester resin, add 5 parts of blocked isocyanate, 1 part of leveling agent, 0.5 parts of degassing agent, and 25 parts of titanium dioxide. Extrude the mixture at a temperature range of 110-120℃, cool, and then pulverize to D... 50 The matrix resin was obtained with a particle size range of 35-50 μm.

[0016] Specifically, the bisphenol A type epoxy resin is E-12 (604) type, with a number average molecular weight of 1400-1600 g / mol and an epoxy equivalent of 700-800 g / eq; the carboxylated polyester resin is a random polymer of terephthalic acid, isophthalic acid and neopentyl glycol, wherein the molar content of isophthalic acid is 5-10%, the number average molecular weight of the carboxylated polyester resin is 3000-4500 g / mol, and the acid value is 70-85 mg KOH / g; the blocked isocyanate is a trimer of isophorone diisocyanate, the end-capping agent is ε-caprolactam, and the initial unblocking temperature is 160℃; the degassing agent is benzyl alcohol; the titanium dioxide is rutile titanium dioxide with an average particle size of 0.22-0.25 μm; and the leveling agent is BYK-361N.

[0017] 96-102 parts of matrix resin and 4 parts of modified graphene resin were mixed under nitrogen protection, and the mixing temperature was controlled within the range of 55-65℃. After mixing at 700 rpm for 5 minutes, the mixture was passed through a heat treatment zone at 105℃ for 10 seconds. Then, cooling water was introduced to cool the mixture down to 30℃ before discharge to obtain powder coating.

[0018] The powder coating is applied under a voltage of 60-70kV and a powder supply pressure of 0.2MPa. After spraying, the powder is kept at 140℃ for 5 minutes to level it. Then, the temperature is increased to 200℃ at a rate of 5-10℃ / min and kept at 20℃ for 10 minutes to obtain the coating.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. Graphene oxide is modified using ionic liquids with epoxy groups. During liquid-phase reduction, the ionic liquid not only acts as a reduction stabilizer to prevent graphene stacking, but its side-chain epoxy groups also chemically crosslink with the matrix resin during subsequent curing. The modified graphene transforms from a heterogeneous filler into crosslinking nodes, effectively improving the coating's impact resistance and adhesion. Meanwhile, the ionic liquid is chemically anchored on the graphene surface and within the resin network, ensuring the coating's antistatic durability.

[0021] 2. A branched polyester with terminal hydroxyl groups was used as the primary carrier for modified graphene. While increasing the graphene loading, a high-shear premixing and low-temperature extrusion process was employed. The wettability of the branched polyester at low viscosity facilitated the exfoliation of the modified graphene sheets, yielding a modified graphene resin. When the modified graphene resin was subsequently mixed with the matrix resin, due to the rheological viscosity difference, the low-viscosity modified masterbatch preferentially carried graphene to the coating surface and interparticle spaces after melting, thereby constructing a surface-enriched conductive network. This ensured the coating's excellent antistatic properties while avoiding interference with the glossy base color.

[0022] 3. A specific matrix resin formulation is employed, combining the characteristics of bisphenol A type epoxy resin and carboxylated polyester, and introducing blocked isocyanate as an auxiliary curing agent. This ensures that the matrix resin maintains a low-viscosity, leveling state within a specific temperature range and rapidly crosslinks upon heating. This wide low-viscosity window guarantees the coating's gloss while allowing sufficient rearrangement time for the modified graphene sheets in the melt, enabling them to automatically assemble into a more complete conductive network under thermodynamic drive. Furthermore, the active groups contained in the ionic liquid also participate in the crosslinking reaction under the action of the matrix resin's curing agent, not only preventing the migration or aggregation of graphene during long-term use but also significantly improving the coating's impact resistance and adhesion.

[0023] 4. The modified graphene resin composited with branched polyester is pulverized to D... 50 The particle size is <5μm, while the matrix resin is pulverized to D. 50 With a particle size range of 35-50 μm, the modified graphene resin powder is first mixed at a low temperature, allowing it to adhere to the surface of a larger matrix resin. This is followed by a short heat treatment to achieve surface spheroidization. Traditional melt extrusion mixing easily cuts the graphene sheets, while this invention's process, through external bonding, protects the high aspect ratio of the graphene and concentrates the conductive material on the particle surface. During curing, the contact interfaces between the particles become highly conductive pathways, significantly reducing surface resistivity. Simultaneously, the spheroidization treatment eliminates micro-roughness, further enhancing the coating's gloss and reflectivity. Attached Figure Description

[0024] Figure 1 This is a flow chart of the preparation process of powder coatings and coatings in this invention. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below through some embodiments and experimental examples. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Reference Figure 1 The process flow diagram shown illustrates that this invention provides a graphene-modified antistatic high-gloss powder coating and its preparation method. The technical solution is as follows:

[0027] Example 1

[0028] Two parts of graphene oxide were added to 400 parts of an ethanol-water solution and ultrasonically dispersed at 400W for 1 hour to obtain a graphene oxide dispersion. The volume fraction of ethanol in the ethanol-water solution was 50%.

[0029] The sheet diameter of graphene oxide is 5-10 μm, the monolayer ratio is >90%, and the oxygen content is >30%.

[0030] One part of ionic liquid was added dropwise to a graphene oxide dispersion, and after stirring at 55°C for 2 hours, 0.5 parts of sodium ascorbate were added. The mixture was then heated to 80°C and refluxed for 4 hours. After the reaction was completed, the mixture was spray-dried at an inlet air temperature of 180°C and an outlet air temperature of 80°C to obtain modified graphene.

[0031] The ionic liquid is specifically 1-(2,3-epoxypropyl)-3-methylimidazolium chloride, which is synthesized as follows: 8.2 parts of N-methylimidazolium are dissolved in ethyl acetate under nitrogen protection, and 10.2 parts of epichlorohydrin are added under stirring. The mixture is heated to 80°C and then refluxed and stirred for 36 hours. After cooling, the product is ultrasonically washed with ethyl acetate and then vacuum dried to obtain the ionic liquid.

[0032] Five parts of modified graphene, 0.5 parts of dispersant, and 95 parts of branched polyester were mixed at 40°C and 3000 rpm for 3 minutes, and then extruded. The extrusion process involved four zones: zone 1 at 80°C, zone 2 at 90°C, and zones 3 and 4 at 95°C. The screw speed was set to 400 rpm. After cooling, the extruded sheet was pulverized to D... 50 After reaching a thickness of <5μm, a modified graphene resin is obtained.

[0033] The dispersant is BYK-163; the branched polyester comprises a main chain formed by esterification of 2,2-dimethylolpropionate, with trimethylolpropane as the end group, a weight-average molecular weight of 3000-4000 g / mol, and a hydroxyl value of 470-520 mg KOH / g.

[0034] Mix 50 parts of bisphenol A type epoxy resin and 40 parts of carboxylated polyester resin, add 5 parts of blocked isocyanate, 1 part of leveling agent, 0.5 parts of degassing agent, and 25 parts of titanium dioxide, and extrude the mixture at a temperature range of 110-120℃. After cooling, pulverize to D. 50 The matrix resin was obtained with a particle size range of 35-50 μm.

[0035] Specifically, the bisphenol A type epoxy resin is E-12 (604) type, with a number average molecular weight of 1400-1600 g / mol and an epoxy equivalent of 700-800 g / eq; the carboxylated polyester resin is a random polymer of terephthalic acid, isophthalic acid and neopentyl glycol, wherein the molar content of isophthalic acid is 5-10%, the number average molecular weight of the carboxylated polyester resin is 3000-4500 g / mol, and the acid value is 70-85 mg KOH / g; the blocked isocyanate is a trimer of isophorone diisocyanate, the end-capping agent is ε-caprolactam, and the initial unblocking temperature is 160℃; the degassing agent is benzyl alcohol; the titanium dioxide is rutile titanium dioxide with an average particle size of 0.22-0.25 μm; and the leveling agent is BYK-361N.

[0036] 96 parts of matrix resin and 4 parts of modified graphene resin were mixed under nitrogen protection, and the mixing temperature was controlled within the range of 55-65℃. After mixing at 700 rpm for 5 minutes, the mixture was passed through a heat treatment zone at 105℃ for 10 seconds. Then, cooling water was introduced to cool the mixture down to 30℃ before discharge to obtain powder coating.

[0037] The powder coating is applied under a voltage of 60-70kV and a powder supply pressure of 0.2MPa. After spraying, the powder is kept at 140℃ for 5 minutes to level it. Then, the temperature is increased to 200℃ at a rate of 5℃ / min and kept at 20℃ for 10 minutes to obtain the coating.

[0038] Examples 2-16 differ from Example 1 in operating parameters, but the other process steps and the range of raw material selection are the same.

[0039] The specific changes in operating parameters are summarized in Table 1.

[0040] Table 1. Changes in operating parameters in Examples 1-16

[0041]

[0042] Comparative Example 1

[0043] Unlike Example 1, no ionic liquid was added, but all other process parameters remained the same.

[0044] Comparative Example 2

[0045] Unlike Example 1, an equal mass fraction of 1-butyl-3-methylimidazolium chloride was used instead of the ionic liquid, while all other process parameters remained the same.

[0046] Comparative Example 3

[0047] Unlike Example 1, liquid-phase reduction was not performed. Instead, the reduced graphene powder, ionic liquid, and branched polyester were directly mixed in an extruder, with all other process parameters remaining the same.

[0048] Comparative Example 4

[0049] Unlike Example 5, no modified graphene resin was prepared. Instead, modified graphene, dispersant, and branched polyester were directly mixed and extruded with the matrix resin, followed by the same nitrogen-protected mixing and heat treatment process, with all other process parameters being the same.

[0050] Comparative Example 5

[0051] Unlike Example 5, the temperatures of the three and four zones of the modified graphene resin extrusion were set to 120°C, while all other process parameters remained the same.

[0052] Comparative Example 6

[0053] Unlike Example 9, a trimer of isophorone diisocyanate without ε-caprolactam capping was used instead of the blocked isocyanate, while all other process parameters remained the same.

[0054] Comparative Example 7

[0055] Unlike Example 9, no blocked isocyanate was added, but all other process parameters were the same.

[0056] Comparative Example 8

[0057] Unlike Example 9, constant temperature leveling at 140°C was not performed. After spraying, the coating was directly cured at 200°C for 15 minutes. All other process parameters were the same.

[0058] Comparative Example 9

[0059] Unlike Example 13, the modified graphene resin was pulverized to D... 50 The particle size range is 35-50μm, and all other process parameters are the same.

[0060] Comparative Example 10

[0061] Unlike Example 13, no short-term heat treatment was performed, but all other process parameters remained the same.

[0062] Experimental Example 1

[0063] The adhesion, impact resistance and antistatic durability of the coating products prepared in Examples 1-4 and Comparative Examples 1-3 were tested, and the relevant results are summarized in Table 2.

[0064] All substrates used in the tests were made of Q235B carbon steel with an average surface roughness Ra of 5 μm.

[0065] The adhesion test method refers to the relevant test method in GB / T 9286. The target coating thickness is 100μm and the grid spacing is 2mm. The adhesion level is tested (0-5, with 0 being the best).

[0066] The impact resistance test method refers to the relevant test method in GB / T 1732. The target coating thickness is 100μm. A 1kg hammer is used to drop freely onto the sample and the maximum height (cm) that does not cause damage to the paint film is recorded. The maximum pass limit of the test is 50cm.

[0067] The test method for antistatic durability is as follows: refer to the relevant test method of GB / T 1410, the target coating thickness is 100μm, the initial resistivity R0 of the coating surface is tested at 100V, wiped with anhydrous ethanol and allowed to dry naturally, and the surface resistivity R1 is tested again after 50 cycles. The resistance change rate δ=lgR1-lgR0 is calculated. The smaller the δ value, the better the antistatic durability.

[0068] Table 2. Adhesion, impact resistance, and antistatic durability of the coating products prepared in Examples 1-4 and Comparative Examples 1-3.

[0069]

[0070] As shown in Table 2, Examples 1 to 4 are significantly better than Comparative Examples 1, 2 and 3 in terms of adhesion, impact resistance and antistatic durability. This indicates that the present invention has significant advantages in improving the mechanical properties and functional stability of the coating by using an ionic liquid with epoxy groups to modify graphene oxide in situ.

[0071] Comparative Example 1, without the addition of ionic liquid during preparation, resulted in graphene oxide readily stacking and agglomerating during reduction. These agglomerates, acting as heterogeneous fillers, disrupted the continuity of the resin matrix, leading to a significant decrease in coating adhesion and impact resistance. Furthermore, due to the lack of ionic liquid's auxiliary conductivity and chemical anchoring effects, its antistatic durability was the worst. Comparative Example 2 used an ionic liquid without active groups to replace the epoxy-functionalized ionic liquid. While this improved dispersibility to some extent, the lack of epoxy groups that could react with the matrix resin prevented the ionic liquid from being chemically locked within the resin network. During ethanol wiping, it easily migrated and was lost, resulting in a large change in resistivity and the inability to form an effective cross-linked reinforcing structure, thus limiting the improvement in impact resistance. Comparative Example 3 omitted the liquid-phase reduction modification step and directly used physical mixing and extrusion. This resulted in the ionic liquid failing to achieve uniform molecular-level coating and interface modification of the graphene. The weak interfacial bonding between graphene and the resin matrix led to poor coating adhesion, failing to realize the reinforcing effect of the modified material.

[0072] In summary, this invention introduces ionic liquids with epoxy groups and combines them with a liquid-phase in-situ modification process, resulting in a significant synergistic effect. In the liquid-phase system, the ionic liquid acts as a dispersant and stabilizer, effectively inhibiting the stacking of graphene. During the curing and film-forming stage, the epoxy groups on the side chains of the ionic liquid chemically crosslink with the matrix resin, transforming the graphene from a simple filler particle into a crosslinked node within the resin network. This chemical bond anchoring mechanism not only firmly locks the ionic liquid onto the graphene surface and within the polymer network, ensuring excellent and durable antistatic properties, but also significantly enhances the adhesion and impact resistance of the coating by constructing a high-strength interfacial bond, achieving simultaneous optimization of antistatic function and coating mechanical properties.

[0073] Experimental Example 2

[0074] The surface resistivity and gloss under 60° light were tested on the coating products prepared in Examples 5-8 and Comparative Examples 4-5. The relevant results are summarized in Table 3.

[0075] The surface resistivity was tested under the same conditions as in Experiment 1, but only the initial resistivity (Ω / sq) was recorded.

[0076] For gloss under 60° illumination, refer to the relevant test method in GB / T 9754. Measure five points on the sample in parallel at an incident angle of 60°, record the gloss (GU), and take the average value.

[0077] Table 3. Surface resistivity and gloss of the coated products prepared in Examples 5-8 and Comparative Examples 3-5

[0078]

[0079] As shown in Table 3, Examples 5 to 8 are significantly better than Comparative Examples 4 and 5 in terms of surface resistivity and gloss, indicating that the process of preparing modified graphene resin using branched polyester as a carrier has obvious advantages in constructing a highly efficient conductive network and maintaining a high-gloss appearance.

[0080] Comparative Example 4 did not prepare a modified graphene resin masterbatch. Instead, modified graphene, dispersant, and branched polyester were directly mixed with the matrix resin and extruded. This lacked the high-shear pre-dispersion and sheet-peeling processes, and prevented the formation of a directional migration mechanism based on viscosity differences. Consequently, graphene could not be effectively enriched on the coating surface, significantly increasing surface resistivity. Simultaneously, the randomly distributed fillers interfered with overall leveling, leading to a decrease in gloss. Comparative Example 5, although using a masterbatch method, had an excessively high extrusion temperature, resulting in an excessively low melt viscosity of the branched polyester. This insufficient shear force was unable to peel off the graphene sheets, causing uneven dispersion and even agglomeration of graphene in the masterbatch. These agglomerates not only severely hindered the construction of conductive pathways but also acted as microscopic defects, significantly damaging the surface smoothness of the coating and resulting in the worst gloss performance.

[0081] In summary, this invention utilizes terminally hydroxylated branched polyester as a carrier and strictly controls the high-shear premixing and low-temperature extrusion process parameters, resulting in a significant synergistic effect. The low-temperature, high-shear environment leverages the wettability of the branched polyester to effectively exfoliate and disperse the graphene sheets. Subsequently, the rheological viscosity difference between the modified masterbatch and the matrix resin drives the low-viscosity masterbatch to preferentially migrate graphene to the coating surface and interparticle spaces. This surface enrichment mechanism significantly reduces surface resistivity while minimizing the interference of conductive fillers on the glossy base color of the resin matrix, achieving a balance between excellent antistatic properties and a high-gloss appearance.

[0082] Experimental Example 3

[0083] The gloss, impact resistance, and adhesion of the coatings prepared in Examples 9-12 and Comparative Examples 6-8 were tested. The results are summarized in Table 4.

[0084] For the gloss test method, refer to Experiment Example 2; for the impact resistance and adhesion test methods, refer to Experiment Example 1.

[0085] Table 4. Gloss, impact resistance, and adhesion of the coatings prepared in Examples 9-12 and Comparative Examples 6-8

[0086]

[0087] As shown in Table 4, Examples 9 to 12 are significantly better than Comparative Examples 6, 7 and 8 in terms of gloss, impact resistance and adhesion, indicating that the introduction of closed isocyanate combined with gradient curing process in this invention has obvious advantages in controlling the leveling window and enhancing interfacial bonding.

[0088] Comparative Example 6 used unblocked isocyanate instead of blocked isocyanate, causing the active groups to react rapidly in the early stages of melting, drastically increasing the system viscosity, losing the necessary leveling time, resulting in a significant decrease in gloss and impaired uniformity of the cured network, as well as poorer impact resistance. Comparative Example 7 did not add blocked isocyanate, lacking components that regulate melt rheological behavior and key crosslinking points with the ionic liquid active groups, resulting in insufficient leveling ability and inability to form a chemically anchored structure, with neither gloss nor mechanical properties reaching optimal levels. Comparative Example 8 omitted the isothermal leveling step, directly curing at high temperature, causing the resin to quickly cross the low viscosity range, leaving the modified graphene insufficient time for thermodynamic rearrangement and self-assembly, severely affecting the final surface smoothness and gloss performance.

[0089] In summary, this invention introduces blocked isocyanate into a bisphenol A type epoxy resin and carboxylated polyester resin system, combined with a specific gradient curing process, resulting in a significant synergistic effect. During the low-temperature leveling stage, the inertness of the blocked isocyanate maintains a wide low-viscosity window, providing ample time for sufficient resin leveling and ordered rearrangement of the modified graphene, ensuring excellent gloss. During the high-temperature curing stage, the unblocked isocyanate not only promotes rapid cross-linking of the matrix but also chemically reacts with the active groups of the ionic liquid side chains, firmly anchoring the graphene within the polymer network. This significantly improves the coating's impact resistance and adhesion while maintaining high appearance quality.

[0090] Experiment Example 4

[0091] The surface resistivity, gloss, and sharpness of the coating products prepared in Examples 13-16 and Comparative Examples 9-10 were tested, and the results are summarized in Table 5.

[0092] For the surface resistivity test method, refer to Experiment Example 1; for the gloss test method, refer to Experiment Example 2.

[0093] The test method for sharpness of light refers to the relevant test method of ASTM D5767 standard. The test is conducted using a 60° point light source, and the surface DOI value of the sample is recorded. The higher the DOI value, the better the sharpness of light.

[0094] Table 5. Surface resistivity, gloss, and sharpness of the coated products prepared in Examples 13-16 and Comparative Examples 9-10

[0095]

[0096] As shown in Table 5, Examples 13 to 16 are significantly better than Comparative Examples 9 and 10 in terms of reflectivity, gloss, and surface resistivity. This indicates that the present invention uses micro-powder particle size matching and short-time heat treatment, which makes the complete technical solution have obvious advantages in constructing surface conductive pathways and eliminating micro-roughness.

[0097] Comparative Example 9 pulverized the modified graphene resin to the same particle size range as the matrix resin, disrupting the particle size distribution design of small particles coating large particles. This resulted in the conductive components failing to form a continuous and dense coating layer on the matrix surface, instead exhibiting a random distribution. Consequently, the surface resistivity increased significantly, and the non-uniform contact between particles reduced the appearance quality of the coating. Comparative Example 10, although it performed particle size matching of the microparticles, omitted the short-time heat treatment step. This allowed the microparticles adsorbed on the matrix surface to maintain their original physical morphology, resulting in microscopic roughness on the coating surface. While maintaining conductivity, this severely affected the clarity of reflected images, leading to a significant decrease in sharpness.

[0098] In summary, this invention prepares modified graphene resin into micropowder and attaches it to the surface of a matrix resin with a larger particle size using an external bonding method. This is followed by a short-time heat treatment process, which produces a significant synergistic effect. The micropowder attachment process utilizes particle size differences to force conductive materials to concentrate on the particle surface. During film curing, highly efficient conductive pathways are directly constructed at the particle contact interface, significantly reducing the percolation threshold. The subsequent heat treatment process eliminates the surface micro-roughness caused by micropowder adsorption, achieving spheroidization and shaping of the particle surface. While ensuring excellent conductivity, this significantly improves the coating's reflectivity and final appearance, solving the technical problem that external fillers typically lead to a decline in appearance.

[0099] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a graphene-modified antistatic high-gloss coating, characterized in that: The preparation method is as follows: Ionic liquid was added dropwise to a graphene oxide dispersion for liquid-phase reduction treatment, and the modified graphene was obtained after drying. The modified graphene is premixed and extruded with a dispersant and branched polyester, and the resulting sheet is pulverized to obtain modified graphene resin. Bisphenol A type epoxy resin, carboxylated polyester resin and blocked isocyanate are mixed, extruded, cooled and then pulverized to obtain the matrix resin; The matrix resin and the modified graphene resin are mixed under nitrogen protection and passed through a heat treatment zone. After cooling, the mixture is discharged to obtain a powder coating. After the powder coating is sprayed, it is kept at a constant temperature for leveling, and then heated and kept at a constant temperature to obtain the coating. The ionic liquid is specifically 1-(2,3-epoxypropyl)-3-methylimidazolium chloride. The specific synthesis method is as follows: N-methylimidazolium is dissolved in ethyl acetate under nitrogen protection, epichlorohydrin is added under stirring, the mixture is heated and stirred to react, the product is ultrasonically washed with ethyl acetate after cooling, and the ionic liquid is obtained after vacuum drying.

2. The method for preparing a graphene-modified antistatic high-gloss coating according to claim 1, characterized in that: The particle size range of the matrix resin pulverization is D. 50 =35-50μm.

3. The method for preparing a graphene-modified antistatic high-gloss coating according to claim 1, characterized in that: The blocked isocyanate is specifically a trimer of isophorone diisocyanate, and the capping agent is ε-caprolactam.

4. The method for preparing a graphene-modified antistatic high-gloss coating according to claim 1, characterized in that: The powder coating is kept at a constant temperature of 140°C, and then heated to 200°C at a rate of 5-10°C / min and held at that temperature for 10 min to obtain the coating.

5. The method for preparing a graphene-modified antistatic high-gloss coating according to claim 1, characterized in that: The heat treatment zone has a treatment temperature of 105°C and a treatment time of 10 seconds.

6. A graphene-modified antistatic high-gloss coating, characterized in that: The graphene-modified antistatic high-gloss coating is prepared by the preparation method described in any one of claims 1-5.

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