Fluorocarbon powder coating

Abstract

The application relates to the technical field of powder coating, and particularly discloses fluorocarbon powder coating. The preparation raw materials of the fluorocarbon powder coating include polyester resin, FEVE resin, PVDF resin, modified graphene composite material, straight-chain dibasic acid, crosslinking agent, isocyanuric acid triglycidyl ester, accelerator, leveling agent, antioxidant and pigment; the preparation raw materials of the modified graphene composite material include graphene nanosheet, precipitated barium sulfate, citric acid and trihydroxyethyl isocyanurate. The fluorocarbon powder coating has the advantages of FEVE resin and PVDF resin, the cost is reduced, the modified graphene composite material can enhance the structural stability and weather resistance of the coating, and the problems of gloss loss, discoloration and cracking of the coating in a long-term exposure to ultraviolet radiation, rain erosion and other harsh environments are reduced.

Description

Technical Field

[0001] This invention relates to the field of powder coating technology, and more particularly to fluorocarbon powder coatings. Background Technology

[0002] Powder coatings, as an environmentally friendly coating material, are widely used in construction, home appliances, automobiles, furniture, and other fields due to their solvent-free nature, high utilization rate, and excellent performance. Especially in outdoor applications, such as metal roof tiles, which are exposed to harsh conditions such as ultraviolet radiation, rain erosion, temperature changes, and air pollutants for extended periods, weather resistance becomes a core performance indicator, directly affecting the coating's service life and protective effect.

[0003] Currently, conventional weather-resistant powder coatings are mainly based on systems such as polyester resin and epoxy resin. These materials offer advantages such as low cost and simple processing in routine applications. However, in outdoor scenarios requiring high weather resistance, the performance of existing powder coatings is significantly insufficient. After prolonged exposure to rain and ultraviolet radiation, the coating is prone to chalking, loss of gloss, discoloration, and even cracking. To achieve higher weather resistance, existing technologies typically employ systems based on PVDF fluorocarbon resin. However, due to the high cost of PVDF resin—fluorocarbon resin itself is much more expensive than conventional resins such as polyester—and the need for a high proportion (30% or higher) of fluorocarbon resin in the formulation to achieve sufficient performance, its application is limited. Summary of the Invention

[0004] In order to reduce manufacturing costs while enhancing the structural stability and weather resistance of the coating and reducing problems such as coating cracking and peeling, this application provides fluorocarbon powder coatings.

[0005] Firstly, the fluorocarbon powder coating provided in this application adopts the following technical solution:

[0006] Fluorocarbon powder coatings, by weight, are prepared from the following raw materials:

[0007] Polyester resin 35-45 parts, FEVE resin 25-35 parts, PVDF resin 4-6 parts, modified graphene composite material 10-12 parts, linear dicarboxylic acid 2.5-4.5 parts, crosslinking agent 6.5-8.5 parts, triglycidyl isocyanurate 2.5-3.5 parts, accelerator 0.13-0.17 parts, leveling agent 0.8-1.2 parts, antioxidant 0.2-0.4 parts, pigment 0-5 parts;

[0008] The raw materials for preparing the modified graphene composite material include graphene nanosheets, precipitated barium sulfate, citric acid and trihydroxyethyl isocyanurate, and the weight ratio of the graphene nanosheets, precipitated barium sulfate, citric acid and trihydroxyethyl isocyanurate is 1:(0.3-0.5):(1-1.4):(0.2-0.3).

[0009] By adopting the above technical solution, this application uses polyester resin as the base resin and adds FEVE resin and PVDF resin as fluorocarbon resins to the system, where they work synergistically. Specifically, FEVE resin replaces a portion of the PVDF resin to reduce the amount of PVDF resin used. FEVE resin also promotes the compatibility between the PVDF resin and the base resin. The combination of the two effectively prevents the coating from losing its gloss, discoloring, or even cracking under prolonged rain erosion and long-term ultraviolet radiation, significantly improving the overall weather resistance of the resin.

[0010] Graphene nanosheets in modified graphene composites possess excellent physical barrier properties. Precipitated barium sulfate enhances the material's stability. Modification with citric acid and trihydroxyethyl isocyanurate allows the composite to be better dispersed in the coating system, forming an effective barrier network and significantly improving the coating's weather resistance and corrosion resistance. Introducing linear dicarboxylic acids into the polyester resin molecular chain enhances the flexibility of the polyester resin segments, ensuring good flowability during powder coating curing, resulting in a smoother, more even coating surface with a better appearance, while also improving the coating's flexibility. Crosslinking agents, triglycidyl isocyanurate, and accelerators work together to promote crosslinking reactions in the coating system. The crosslinking agent forms bridges connecting molecular chains during the reaction, triglycidyl isocyanurate participates in the crosslinking reaction, increasing crosslinking points, and the accelerator accelerates the reaction rate. These three synergistically increase the crosslinking network density, making the coating structure more compact, reducing the channels for external substances to enter, and thus improving the coating's corrosion resistance. The synergistic effect of the various components gives this fluorocarbon powder coating excellent weather resistance, corrosion resistance and mechanical properties. Compared with using PVDF fluorocarbon resin system alone, it reduces costs and expands the application range.

[0011] Preferably, the preparation method of the modified graphene composite material includes the following steps:

[0012] (1) Mix graphene nanosheets with precipitated barium sulfate, add water and stir evenly to obtain a dispersion, add sodium hydroxide to the dispersion, heat to 60-70℃, stir for 20-30 min, filter, wash and dry to obtain pretreated graphene composite material.

[0013] (2) The pretreated graphene composite material is uniformly dispersed in a solvent to form a suspension; citric acid is dissolved in the solvent to obtain a citric acid solution; trihydroxyethyl isocyanurate is dissolved in the solvent to obtain a trihydroxyethyl isocyanurate solution; the citric acid solution is added dropwise to the suspension, heated to 60-70℃, stirred for 1-2 hours, and then the trihydroxyethyl isocyanurate solution is added dropwise, and the reaction is continued for 1-2 hours. After filtration, washing, and drying, the modified graphene composite material is obtained.

[0014] By adopting the above technical solution, citric acid and trihydroxyethyl isocyanurate are used to modify graphene nanosheets and precipitated barium sulfate. Citric acid contains carboxyl and hydroxyl active groups, which can react with the functional groups on the surface of the pretreated graphene composite material to increase the active sites on the material surface. Trihydroxyethyl isocyanurate contains a triazine ring and three hydroxyethyl groups, which can undergo esterification with the carboxyl groups on the citric acid-modified material in further reactions to form stable chemical bonds. This allows the modified graphene composite material to be better dispersed in the coating system, with the graphene nanosheets being uniformly distributed, while the precipitated barium sulfate fills the gaps between the sheets, enhancing the barrier properties of the coating film.

[0015] Preferably, the straight-chain dicarboxylic acid is selected from one or both of azelaic acid and sebacic acid.

[0016] By adopting the above technical solution, azelaic acid and sebacic acid have long carbon chains. During the coating curing process, the long carbon chains can form a more flexible molecular network structure inside the coating. When the coating is subjected to external force, the molecular chains can undergo a certain degree of deformation to buffer the stress, enhance the toughness of the coating, reduce cracking and embrittlement caused by external impact, temperature change and other factors during the use of the coating, and improve the impact resistance and durability of fluorocarbon powder coating.

[0017] Preferably, the polyester resin is a carboxyl-terminated polyester resin, the acid value of the carboxyl-terminated polyester resin is 30-60 mgKOH / g, and the number-average molecular weight of the carboxyl-terminated polyester resin is 4000-7500.

[0018] By adopting the above technical solutions, a suitable acid value provides certain carboxyl reaction sites for the polyester resin, increasing its chemical reactivity with other materials and helping to improve the crosslinking density and mechanical strength of the material. Furthermore, combining carboxyl-terminated polyester resin with fluorocarbon resin allows fluorocarbon powder coatings to combine the advantages of polyester resin (low cost and simple processing) with fluorocarbon resin (good weather resistance), thus reducing costs while improving the coating's weather resistance in outdoor environments.

[0019] Preferably, the crosslinking agent is a self-sealing polyurethane crosslinking agent. BF1540.

[0020] By adopting the above technical solution, the crosslinking agent has the characteristics of low-temperature stable storage and high-temperature controllable unsealing and crosslinking, realizing low-temperature curing of coating film and high-performance network construction.

[0021] Preferably, the accelerator is selected from one or more of ethyltriphenylphosphine bromide, tetrabutylammonium chloride, and benzyltrimethylammonium chloride.

[0022] Preferably, the leveling agent is Huahui T-988 leveling agent.

[0023] By adopting the above technical solutions, leveling agents significantly improve the gloss and image quality of coatings by reducing the surface tension of the coating and eliminating fisheye and pinhole effects.

[0024] Preferably, the antioxidants are antioxidant 1010 and antioxidant 168, and the weight ratio of antioxidant 1010 to antioxidant 168 is 1:(0.6-0.8).

[0025] By adopting the above technical solution, the combined use of antioxidant 1010 and antioxidant 168 can enhance the antioxidant capacity of fluorocarbon powder coatings, prevent the coatings from being oxidized during storage and use, and extend the service life and protective effect of the coatings.

[0026] Preferably, the graphene nanosheets have a thickness of 8-16 nm and a sheet planar size of 1-2 μm.

[0027] By adopting the above technical solution, modified graphene composite materials are prepared using graphene nanosheets with specific thickness and planar dimensions. When applied to fluorocarbon powder coatings, the weather resistance of fluorocarbon powder coatings under harsh outdoor conditions can be improved.

[0028] Secondly, the preparation method of the fluorocarbon powder coating provided in this application adopts the following technical solution:

[0029] A method for preparing fluorocarbon powder coatings includes the following steps:

[0030] Weigh the raw materials according to the component ratio, and mix polyester resin, FEVE resin, PVDF resin, modified graphene composite material, linear dicarboxylic acid, crosslinking agent, triglycidyl isocyanurate, accelerator, leveling agent, antioxidant, and pigment at high speed. Melt and knead the uniformly mixed material at 155-170℃, extrude, press into sheets and cool to room temperature, and then pulverize at high speed and sieve to obtain fluorocarbon powder coating.

[0031] By adopting the above technical solution and preparation method, the raw materials are fully and uniformly mixed and melt-blended at a specific temperature to allow for full intermolecular reaction. The resulting fluorocarbon powder coating combines the advantages of polyester resin, FEVE resin, and PVDF resin, reducing costs. The added modified graphene composite material can enhance the structural stability and weather resistance of the coating, reduce problems such as loss of gloss, discoloration, and cracking caused by long-term exposure to harsh environments such as ultraviolet radiation and rain erosion, and improve the service life and protective effect of the coating film.

[0032] This application has the following beneficial effects:

[0033] This application uses polyester resin as the base resin and adds FEVE resin and PVDF resin as fluorocarbon resins to the system, where they work synergistically. FEVE resin replaces a portion of the PVDF resin to reduce the amount of PVDF resin used. FEVE resin also promotes compatibility between the PVDF resin and the base resin. The combination of the two effectively prevents the coating from losing its gloss, discoloring, or even cracking under prolonged rain erosion and long-term ultraviolet radiation, significantly improving the overall weather resistance of the resin.

[0034] Graphene nanosheets in modified graphene composites possess excellent physical barrier properties. Precipitated barium sulfate enhances the material's stability. Modification with citric acid and trihydroxyethyl isocyanurate allows the composite to be better dispersed in the coating system, forming an effective barrier network and significantly improving the coating's weather resistance and corrosion resistance. Introducing linear dicarboxylic acids into the polyester resin molecular chain enhances the flexibility of the polyester resin segments, ensuring good flowability during powder coating curing, resulting in a smoother, more even coating surface with a better appearance, while also improving the coating's flexibility. Crosslinking agents, triglycidyl isocyanurate, and accelerators work together to promote crosslinking reactions in the coating system. The crosslinking agent forms bridges connecting molecular chains during the reaction, triglycidyl isocyanurate participates in the crosslinking reaction, increasing crosslinking points, and the accelerator accelerates the reaction rate. These three synergistically increase the crosslinking network density, making the coating structure more compact, reducing the channels for external substances to enter, and thus improving the coating's corrosion resistance. The synergistic effect of the various components gives this fluorocarbon powder coating excellent weather resistance, corrosion resistance and mechanical properties. Compared with using PVDF fluorocarbon resin system alone, it reduces costs and expands the application range. Detailed Implementation

[0035] Preparation Example

[0036] Preparation Example 1

[0037] Preparation of modified graphene composite materials:

[0038] (1) Mix 100g of graphene nanosheets (thickness of 10nm and planar size of 1μm) with 30g of precipitated barium sulfate, add 1000ml of water and stir evenly to obtain a dispersion. Add 200g of sodium hydroxide to the dispersion and heat to 60℃. Stir and react for 20min. Filter, wash and dry to obtain pretreated graphene composite material.

[0039] (2) The pretreated graphene composite material was uniformly dispersed in 500 ml of N,N-dimethylformamide to form a suspension; 100 g of citric acid was dissolved in 250 ml of N,N-dimethylformamide to obtain a citric acid solution; 20 g of trihydroxyethyl isocyanurate was dissolved in 250 ml of N,N-dimethylformamide to obtain a trihydroxyethyl isocyanurate solution; the citric acid solution was added dropwise to the suspension and heated to 60 °C, and stirred for 1 h; then the trihydroxyethyl isocyanurate solution was added dropwise, and the reaction was continued for 1 h; the mixture was filtered, washed three times with a 75% ethanol aqueous solution, and dried to obtain the modified graphene composite material.

[0040] Preparation Example 2

[0041] Preparation of modified graphene composite materials:

[0042] (1) Mix 110g of graphene nanosheets (thickness of 25nm and planar size of 1μm) with 44g of precipitated barium sulfate, add 1000ml of water and stir evenly to obtain a dispersion. Add 200g of sodium hydroxide to the dispersion and heat to 65℃. Stir and react for 25min. Filter, wash and dry to obtain pretreated graphene composite material.

[0043] (2) The pretreated graphene composite material was uniformly dispersed in 500 ml of N,N-dimethylformamide to form a suspension; 132 g of citric acid was dissolved in 250 ml of N,N-dimethylformamide to obtain a citric acid solution; 27.5 g of trihydroxyethyl isocyanurate was dissolved in 250 ml of N,N-dimethylformamide to obtain a trihydroxyethyl isocyanurate solution; the citric acid solution was added dropwise to the suspension and heated to 65 °C, and stirred for 1.5 h; then the trihydroxyethyl isocyanurate solution was added dropwise, and the reaction was continued for 1.5 h; the mixture was filtered, washed three times with a 75% ethanol aqueous solution, and dried to obtain the modified graphene composite material.

[0044] Preparation Example 3

[0045] Preparation of modified graphene composite materials:

[0046] (1) Mix 120g of graphene nanosheets (thickness of 40nm and planar size of 2μm) with 60g of precipitated barium sulfate, add 1000ml of water and stir evenly to obtain a dispersion. Add 200g of sodium hydroxide to the dispersion and heat to 70℃. Stir and react for 30min. Filter, wash and dry to obtain pretreated graphene composite material.

[0047] (2) The pretreated graphene composite material was uniformly dispersed in 500 ml of N,N-dimethylformamide to form a suspension; 168 g of citric acid was dissolved in 250 ml of N,N-dimethylformamide to obtain a citric acid solution; 36 g of trihydroxyethyl isocyanurate was dissolved in 250 ml of N,N-dimethylformamide to obtain a trihydroxyethyl isocyanurate solution; the citric acid solution was added dropwise to the suspension and heated to 70 °C, and stirred for 2 h; then the trihydroxyethyl isocyanurate solution was added dropwise, and the reaction was continued for 2 h; the mixture was filtered, washed three times with a 75% ethanol aqueous solution, and dried to obtain the modified graphene composite material.

[0048] Preparation Example 4

[0049] The difference between this preparation example and preparation example 2 is that citric acid was not added in step (2).

[0050] Preparation Example 5

[0051] The difference between this preparation example and preparation example 2 is that trihydroxyethyl isocyanurate was not added in step (2).

[0052] Example

[0053] Example 1

[0054] Fluorocarbon powder coating, comprising: 350g carboxyl-terminated polyester resin (acid value 30mg KOH / g, number average molecular weight 7500), 250g FEVE resin ( (Covestro) solid fluorocarbon resin PDS-40102), 40g PVDF resin (Sanaifuwanhao PVDFT-2), 100g modified graphene composite material (prepared in Example 1), 25g azelaic acid, 65g crosslinking agent (self-blocking polyurethane crosslinking agent) BF1540), 25g triglycidyl isocyanurate (Huahui TGIC), 1.3g tetrabutylammonium chloride, 8g leveling agent (Huahui T-988 leveling agent), 1.25g antioxidant 1010, 0.75g antioxidant 168, 2g pigment.

[0055] The preparation method of the fluorocarbon powder coating in this embodiment includes the following steps:

[0056] Weigh the raw materials according to the above components, and mix the carboxyl-terminated polyester resin, FEVE resin, PVDF resin, modified graphene composite material, azelaic acid, crosslinking agent, triglycidyl isocyanurate, tetrabutylammonium chloride, leveling agent, antioxidant 1010, antioxidant 168, and pigment at high speed. Melt and knead the uniformly mixed material at 155°C, extrude, press into sheets and cool to room temperature, and then pulverize at high speed and sieve to obtain fluorocarbon powder coating.

[0057] Example 2

[0058] Fluorocarbon powder coating, comprising: 400g carboxyl-terminated polyester resin (acid value 45mg KOH / g, number average molecular weight 6000), 300g FEVE resin ( (Covestro) solid fluorocarbon resin PDS-40102), 50g PVDF resin (Sanaifuwanhao PVDFT-2), 110g modified graphene composite material (prepared in Example 2), 30g sebacic acid, 75g crosslinking agent (self-blocking polyurethane crosslinking agent) BF1540), 30g triglycidyl isocyanurate (Huahui TGIC), 1.5g ethyltriphenylphosphine bromide, 10g leveling agent (Huahui T-988 leveling agent), 1.76g antioxidant 1010, 1.24g antioxidant 168, 3.5g pigment.

[0059] The preparation method of the fluorocarbon powder coating in this embodiment includes the following steps:

[0060] Weigh the raw materials according to the above components, and mix the carboxyl-terminated polyester resin, FEVE resin, PVDF resin, modified graphene composite material, sebacic acid, crosslinking agent, triglycidyl isocyanurate, ethyltriphenylphosphine bromide, leveling agent, antioxidant 1010, antioxidant 168, and pigment at high speed. Melt and knead the uniformly mixed material at 160°C, extrude, press into sheets and cool to room temperature, and then pulverize at high speed and sieve to obtain fluorocarbon powder coating.

[0061] Example 3

[0062] Fluorocarbon powder coating, comprising: 450g carboxyl-terminated polyester resin (acid value 60mg KOH / g, number average molecular weight 4000), 350g FEVE resin ( (Covestro) solid fluorocarbon resin PDS-40102), 60g PVDF resin (Sanaifuwanhao PVDFT-2), 120g modified graphene composite material (prepared in Example 3), 45g sebacic acid, 85g crosslinking agent (self-blocking polyurethane crosslinking agent) BF1540), 35g triglycidyl isocyanurate (Huahui TGIC), 1.7g benzyltrimethylammonium chloride, 12g leveling agent (Huahui T-988 leveling agent), 2.22g antioxidant 1010, 1.78g antioxidant 168, 5g pigment.

[0063] The preparation method of the fluorocarbon powder coating in this embodiment includes the following steps:

[0064] The raw materials were weighed according to the component ratio. The carboxyl-terminated polyester resin, FEVE resin, PVDF resin, modified graphene composite material, sebacic acid, crosslinking agent, triglycidyl isocyanurate, benzyltrimethylammonium chloride, leveling agent, antioxidant 1010, antioxidant 168, and pigment were mixed at high speed. The uniformly mixed materials were melt-blended at 170°C, extruded, pressed into sheets, and cooled to room temperature. After high-speed pulverization, the mixture was sieved to obtain fluorocarbon powder coating.

[0065] Example 4

[0066] The difference between this embodiment and Embodiment 2 is that an equal amount of succinic acid is used instead of sebacic acid.

[0067] Comparative Example

[0068] Comparative Example 1

[0069] The fluorocarbon powder coating differs from Example 2 in that it uses the modified graphene composite material prepared in Preparation Example 4.

[0070] Comparative Example 2

[0071] The fluorocarbon powder coating differs from Example 2 in that it uses the modified graphene composite material prepared in Preparation Example 5.

[0072] Comparative Example 3

[0073] The fluorocarbon powder coating differs from Example 2 in that it uses an equal amount of graphene nanosheets instead of the modified graphene composite material.

[0074] Comparative Example 4

[0075] The fluorocarbon powder coating differs from Example 2 in that an equal amount of precipitated barium sulfate is used instead of the modified graphene composite material.

[0076] Comparative Example 5

[0077] The fluorocarbon powder coating differs from Example 2 in that it uses an equal amount of isophthalic acid instead of sebacic acid.

[0078] Comparative Example 6

[0079] The fluorocarbon powder coating differs from that in Example 2 in that it does not contain PVDF resin.

[0080] Comparative Example 7

[0081] The fluorocarbon powder coating differs from that in Example 2 in that it does not contain FEVE resin.

[0082] Performance testing

[0083] Coating preparation: The powder coatings prepared in Examples 1-4 and Comparative Examples 1-7 were sprayed onto the phosphated metal plate using an electrostatic spray gun, cured at 160℃ for 15 min, and then naturally cooled to room temperature.

[0084] 1. Impact Resistance Test: The impact resistance of the coating is tested using an impact testing machine according to GB / T 20624.2-2006 standard. During the test, a weight of specified mass is dropped freely from different heights onto the powder-coated sample. The impact energy (unit: kg·cm) is used as a quantitative indicator to evaluate the coating's impact resistance. The impact energy is calculated by multiplying the weight's mass by the drop height. The impact resistance data represents the maximum impact energy the coating can withstand without damage (such as cracking or peeling). The higher the value, the better the coating's impact resistance.

[0085] 2. Adhesion test: The test shall be conducted in accordance with GB / T 9286-2021 "Paints and Varnishes Cross-cut Test". Use a sharp blade to cut 100 small squares on the metal plate coated with powder coating. Then stick special tape on the metal plate and quickly tear it off. Observe the coating peeling off within the squares to evaluate the adhesion. The adhesion level is divided into 0-5, with 0 being the best and 5 being the worst.

[0086] 3. Bending performance test: The test shall be conducted in accordance with GB / T 6742-1986 "Bending test of paint film (cylindrical shaft)" with a bending diameter of 2mm. After holding the bending position for 15 seconds, the bending film shall be returned to its original position and the cracking of the coating film shall be observed.

[0087] 4. Hardness test: The hardness of the coatings in Examples 1-4 and Comparative Examples 1-7 were tested according to GB / T6739-2006 "Determination of Hardness of Paints and Varnishes by Pencil Method".

[0088] Table 1:

[0089]

[0090] 5. Salt spray resistance test: According to GB / T 1771-2007 standard, the sample coated with powder coating is placed in a salt spray test chamber at a temperature of 35℃ and a salt solution concentration of 5% for 4000 hours of continuous spraying. The corrosion of the sample is observed. The width of the scribing corrosion is less than 3mm to be considered qualified.

[0091] 6. Weather resistance test: The prepared coating sample was placed under a xenon lamp aging test device for 5000 hours. Each cycle consisted of 8 hours of irradiation and 4 hours of condensation, with different time intervals. The gloss retention rate was tested and recorded in Table 2.

[0092] 7. Chemical resistance test: Immerse the sample in 5% NaOH solution and 3% HCl solution for 7 days respectively, and observe the peeling of the coating.

[0093] Table 2:

[0094]

[0095] Based on the comparison between Example 2 and Comparative Examples 1-2, and the data in Tables 1 and 2, it can be seen that modifying graphene composite materials with citric acid alone or with trihydroxyethyl isocyanurate alone will affect the modification effect of the graphene composite material, resulting in poor durability and corrosion resistance of the coating film. This application uses citric acid and trihydroxyethyl isocyanurate to synergistically modify the graphene composite material. Citric acid provides carboxyl and hydroxyl active groups, while trihydroxyethyl isocyanurate provides a triazine ring and three hydroxyethyl groups. In further reactions, these groups can undergo esterification with the carboxyl groups on the citric acid-modified material, forming stable chemical bonds. This allows the modified graphene composite material to be better dispersed in the coating system, improving the barrier properties of the coating film.

[0096] Based on the comparison of Examples 2 and Comparative Examples 3-4, and the data in Tables 1 and 2, it can be seen that: the graphene nanosheets in Comparative Example 3 were unmodified and prone to agglomeration, forming local weaknesses during the coating curing process and affecting the material's performance. In Comparative Example 4, without the addition of modified graphene composite material, the coating exhibited poor barrier properties against corrosive substances and was prone to swelling and peeling. In contrast, this application, by adding modified graphene composite material, endows the coating with excellent barrier properties, significantly improving its weather resistance and corrosion resistance.

[0097] Based on the comparison between Example 2 and Comparative Example 5, and the data in Tables 1 and 2, it can be seen that the steric hindrance of the isophthalic acid in Comparative Example 5 protects the ester bonds, which can improve the corrosion resistance and weather resistance of the coating to a certain extent. However, its steric hindrance hinders the movement of polyester resin molecular chains, thereby reducing the impact resistance of the coating and making it prone to cracking. After cracking, the coating accelerates corrosion. This application uses a straight-chain dicarboxylic acid with a relatively long carbon chain. During the coating curing process, the long carbon chain can form a more flexible molecular network structure inside the coating. When the coating is subjected to external force, the molecular chain can undergo a certain degree of deformation to buffer the stress, enhance the toughness of the coating, and reduce cracking and embrittlement caused by external impacts, temperature changes, and other factors during use.

[0098] Based on the comparison between Example 2 and Comparative Examples 6-7, as well as the data in Tables 1 and 2, it can be seen that FEVE resin and PVDF resin have a synergistic effect. FEVE resin promotes the compatibility between PVDF resin and the matrix resin. The combination of the two can effectively prevent the coating from losing its gloss, discoloring, or even cracking under long-term rain erosion and long-term ultraviolet radiation, and greatly improve the overall weather resistance of the resin.

[0099] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. Fluorocarbon powder paint, characterized in that, Prepared from the following raw materials by weight parts: Polyester resin 35-45 parts, FEVE resin 25-35 parts, PVDF resin 4-6 parts, modified graphene composite material 10-12 parts, straight-chain dicarboxylic acid 2.5-4.5 parts, crosslinking agent 6.5-8.5 parts, isocyanuric acid triglycidyl ester 2.5-3.5 parts, accelerator 0.13-0.17 parts, leveling agent 0.8-1.2 parts, antioxidant 0.2-0.4 parts, pigment 0-5 parts; The preparation raw materials of the modified graphene composite material include graphene nanosheets, precipitated barium sulfate, citric acid and trihydroxyethyl isocyanurate, and the weight ratio of the graphene nanosheets, precipitated barium sulfate, citric acid and trihydroxyethyl isocyanurate is 1: (0.3-0.5): (1-1.4): (0.2-0.3); The preparation method of the modified graphene composite material includes the following steps: (1) Mix the graphene nanosheets and precipitated barium sulfate, add water and stir until uniform to obtain a dispersion liquid, add sodium hydroxide to the dispersion liquid and heat to 60-70℃, stir for 20-30 min, filter, wash and dry to obtain a pretreated graphene composite material; (2) Disperse the pretreated graphene composite material uniformly in a solvent to form a suspension, dissolve citric acid in the solvent to obtain a citric acid solution, dissolve trihydroxyethyl isocyanurate in the solvent to obtain a trihydroxyethyl isocyanurate solution, add the citric acid solution dropwise to the suspension, heat to 60-70℃, stir for 1-2 h, then add the trihydroxyethyl isocyanurate solution dropwise, continue to react for 1-2 h, and filter, wash and dry to obtain the modified graphene composite material.

2. Fluorocarbon powder paint according to claim 1, characterized in that, The straight-chain dicarboxylic acid is selected from one or both of azelaic acid and eicosanedioic acid.

3. The fluorocarbon powder paint according to claim 1, characterized in that, The polyester resin is a carboxyl-terminated polyester resin, the acid value of the carboxyl-terminated polyester resin is 30-60 mg KOH / g, and the number average molecular weight of the carboxyl-terminated polyester resin is 4000-7500.

4. The fluorocarbon powder paint according to claim 1, characterized in that, The crosslinking agent is a self-blocking polyurethane crosslinking agent VESTAGON® BF1540.

5. The fluorocarbon powder paint of claim 1, wherein, The accelerator is selected from one or more of ethyl triphenyl phosphonium bromide, tetrabutylammonium chloride and benzyl trimethylammonium chloride.

6. The fluorocarbon powder paint of claim 1, wherein, The leveling agent is Huai T-988 leveling agent.

7. The fluorocarbon powder paint of claim 1, wherein, The antioxidant is selected from antioxidant 1010 and antioxidant 168, and the weight ratio of the antioxidant 1010 and the antioxidant 168 is 1: (0.6-0.8).

8. The fluorocarbon powder paint of claim 1, wherein, The thickness of the graphene nanosheets is 10-40 nm, and the size of the sheet layer plane is 1-2 μm.

9. Process for the production of fluorocarbon powder coatings according to any one of claims 1 to 8, characterized in that, The method includes the following steps: Weigh the raw materials according to the component allocation ratio, mix the polyester resin, FEVE resin, PVDF resin, modified graphene composite material, straight-chain dicarboxylic acid, crosslinking agent, isocyanuric acid triglycidyl ester, accelerator, leveling agent, antioxidant and pigment at high speed, melt and mix the uniformly mixed materials at 155-170℃, extrude, press and cool to room temperature, grind at high speed, sieve and obtain fluorocarbon powder coating.

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