Water-based fluorocarbon finish for metal products and preparation method thereof

Abstract

This application relates to the technical field of waterborne coatings, specifically disclosing a waterborne fluorocarbon topcoat for metal products and its preparation method. The waterborne fluorocarbon topcoat for metal products comprises the following raw materials: 24-28 parts of waterborne FEVE fluorocarbon resin, 6-8 parts of organosilicon-modified FEVE resin, 5-7 parts of perfluorodecyl ethyl acrylate, 12-15 parts of nanofiller; 8-10 parts of silica sol, 0.3-0.5 parts of hydroxymethyl propyl cellulose, 1.2-1.6 parts of dipropylene glycol methyl ether, 1.5-2 parts of waterborne polyisocyanate crosslinking agent, 0.3-0.5 parts of leveling agent, and 0.2-0.3 parts of dispersant. The waterborne fluorocarbon topcoat for metal products of this application exhibits excellent high-temperature anti-sticking and self-cleaning properties.

Description

Technical Field

[0001] This invention relates to the technical field of water-based coatings, and in particular to a water-based fluorocarbon topcoat for metal products and its preparation method. Background Technology

[0002] Among the related technologies, a water-based wheel hub topcoat is disclosed, which, by weight, consists of the following components: 20-30 parts water-based pure acrylic acid, 10-15 parts water-based fluorocarbon resin, 50-60 parts metal compound, 5-10 parts kaolin, 5-10 parts silica, 0.5-2 parts polyurethane thickener, 0.2-0.6 parts propylene glycol ethyl ether, 0.3-0.5 parts paint film self-cleaning agent, and the balance being deionized water.

[0003] However, metal products such as wheel hubs are exposed to instantaneous high temperatures during operation. The aforementioned acrylic-based waterborne fluorocarbon topcoat is prone to softening and dust adhesion under instantaneous high temperatures. The dust will sinter and adhere at high temperatures, damaging the appearance of the metal products and accelerating corrosion. Summary of the Invention

[0004] In order to improve the high-temperature anti-sticking properties of waterborne fluorocarbon topcoat when applied to the surface of metal products, this application provides a waterborne fluorocarbon topcoat for metal products and a preparation method thereof.

[0005] Firstly, this application provides a water-based fluorocarbon topcoat for metal products, which adopts the following technical solution:

[0006] A water-based fluorocarbon topcoat for metal products comprises the following raw materials in parts by weight: 24-28 parts of water-based FEVE fluorocarbon resin, 6-8 parts of silicone-modified FEVE resin, 5-7 parts of perfluorodecyl ethyl acrylate, 12-15 parts of nanofiller; 8-10 parts of silica sol, 0.3-0.5 parts of hydroxymethyl propyl cellulose, 1.2-1.6 parts of dipropylene glycol methyl ether, 1.5-2 parts of water-based polyisocyanate crosslinking agent, 0.3-0.5 parts of leveling agent, and 0.2-0.3 parts of dispersing agent.

[0007] In one specific implementation, the nanofiller comprises nano-titanium dioxide, zirconium phosphate, and hydrophobic fumed silica in a weight ratio of (4-5):(3-4):(3-4).

[0008] In one specific implementation, the solid content of the water-based fluorocarbon topcoat on the metal product is 43-47%.

[0009] In one specific implementation, the leveling agent is a polyether-modified polysiloxane or a fluorinated polyether siloxane.

[0010] In one specific implementation, the dispersing agent is a fluorocarbon chain modified acrylate.

[0011] In one specific feasible implementation, PTFE micron powder is also included.

[0012] Secondly, this application provides a method for preparing a water-based fluorocarbon topcoat for metal products, which adopts the following technical solution:

[0013] A method for preparing a water-based fluorocarbon topcoat for metal products includes the following steps:

[0014] According to the above ratio, add the nanofiller and dispersing agent to deionized water, disperse evenly, and grind until the particle size is ≤50μm to obtain the nanofiller dispersion.

[0015] A waterborne FEVE fluorocarbon resin, an organosilicon-modified FEVE resin, and perfluorodecyl ethyl acrylate were mixed evenly to obtain a resin system.

[0016] While stirring, dipropylene glycol methyl ether and hydroxymethyl propyl cellulose were added to the resin system and stirred until homogeneous. The viscosity of the system was monitored in real time during the stirring process. When the viscosity of the system was stable, the nanofiller dispersion was added dropwise while stirring. After the addition was completed, silica sol was added and stirred until homogeneous to obtain the hybrid network system.

[0017] Add leveling agent and water-based polyisocyanate crosslinking agent while stirring. After stirring evenly, filter to obtain water-based fluorocarbon topcoat for metal products.

[0018] In one specific feasible implementation, PTFE micro powder, leveling agent and waterborne polyisocyanate crosslinking agent are added under stirring, stirred evenly and then filtered to obtain waterborne fluorocarbon topcoat for metal products.

[0019] In one specific feasible implementation, after filtration, the solid content of the system is adjusted to 43-47% with deionized water to obtain a water-based fluorocarbon topcoat for metal products.

[0020] In one specific implementation, the method for preparing the organosilicon-modified FEVE resin includes the following steps:

[0021] At 40-50℃, waterborne FEVE fluorocarbon resin is dissolved in propylene glycol methyl ether acetate to form a homogeneous solution;

[0022] Lower the temperature to 30-35℃, and add silane coupling agent KH-560 dropwise while stirring. After the addition is complete, add dibutyltin dilaurate catalyst and continue stirring for 15-20 minutes.

[0023] Heat to 70-80℃, stir continuously for 4-6 hours, cool to room temperature, filter to remove insoluble matter or impurities, and remove part of the organic solvent by vacuum distillation to obtain organosilicon-modified FEVE resin with a solid content of 40-50%.

[0024] In summary, this application has the following beneficial effects:

[0025] 1. This application, by employing a specific ratio of waterborne FEVE fluorocarbon resin, silicone-modified FEVE resin, perfluorodecyl ethyl acrylate, nanofillers, silica sol, waterborne polyisocyanate crosslinking agent, and other additives, can reduce the tackiness of waterborne fluorocarbon topcoats on metal products at 180°C, improve the surface hydrophobicity of the waterborne fluorocarbon topcoat on metal products, and reduce the tackiness change after long-term aging at 180°C. Therefore, the waterborne fluorocarbon topcoat for metal products of this application exhibits excellent high-temperature anti-sticking and self-cleaning properties.

[0026] 2. In this application, a mixture of nano-titanium dioxide, zirconium phosphate and hydrophobic fumed silica in a weight ratio of (4-5):(3-4):(3-4) is preferred as a nanofiller, which can further improve the high-temperature anti-sticking and self-cleaning properties of water-based fluorocarbon topcoat for metal products.

[0027] 3. The method of this application first disperses and grinds the nanofiller at high speed to avoid local performance defects caused by agglomeration; the resin system is premixed before the filler and additives are gradually added to ensure uniform dispersion and avoid the introduction of air bubbles by high-speed stirring. Finally, the solid content is adjusted to ensure uniform coating thickness and stable concentration of functional components on the surface; impurities are removed by filtration to avoid localized increase in viscosity or hydrophobic failure caused by surface protrusions. Detailed Implementation

[0028] Unless otherwise specified, all raw materials used in this application were commercially available. Specifically, the waterborne FEVE fluorocarbon resin was AGC LUMIFLO NFE4400 from Asahi Glass (Japan). Perfluorodecyl ethyl acrylate was Darli Darl-1. Silica sol was Kening J30. Hydroxymethyl propyl cellulose was 5-200000 purchased from Shenyang Xingzhenghe Chemical Co., Ltd. Dipropylene glycol dimethyl ether was purchased from Anhui Lixing New Materials Co., Ltd. The waterborne polyisocyanate crosslinking agent was Bolino BL-3851 purchased from Shanghai Bolino New Materials Technology Co., Ltd. The polyether-modified polysiloxane was BYK-306. PTFE micropowder was Daikin M111 from Japan. Nano-titanium dioxide was NT-50 purchased from Hubei Huifu Nanomaterials Co., Ltd., and the dibutyltin dilaurate catalyst was T-12. Propylene glycol methyl ether acetate was purchased from Guangdong Fangxin Biotechnology Co., Ltd., AR grade. Zirconium phosphate was purchased from Fujian Ruisen New Materials Co., Ltd., model number rs-lsg-c. The hydrophobic fumed silica was Cabot CAB-O-SIL TS620.

[0029] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0030] Example

[0031] Example 1

[0032] This embodiment provides a water-based fluorocarbon topcoat for metal products, comprising the following raw materials: 26 kg of water-based FEVE fluorocarbon resin, 7 kg of silicone-modified FEVE resin, 6.5 kg of perfluorodecyl ethyl acrylate, 13.5 kg of nanofiller; 9 kg of silica sol, 0.4 kg of hydroxymethyl propyl cellulose, 1.4 kg of dipropylene glycol methyl ether, 1.75 kg of water-based polyisocyanate crosslinking agent, 0.4 kg of leveling agent, and 0.25 kg of dispersant. In this embodiment, the nanofiller is nano-titanium dioxide, the leveling agent is fluorinated polyether siloxane, and the dispersant is BYK 220SN wetting and dispersing agent.

[0033] The preparation method of organosilicon-modified FEVE resin includes the following steps:

[0034] At 45°C, 50 kg of waterborne FEVE fluorocarbon resin was added to 40 kg of propylene glycol methyl ether acetate to form a homogeneous solution.

[0035] The temperature was lowered to 33℃, and 6.5 kg of silane coupling agent KH-560 was added dropwise while stirring. After the addition was complete, 0.2 kg of dibutyltin dilaurate catalyst was added, and stirring was continued for 18 min.

[0036] The temperature was raised to 75°C and stirred continuously for 5 hours. Then the mixture was allowed to cool to room temperature, filtered to remove insoluble matter or impurities, and some organic solvent was removed by vacuum distillation to obtain organosilicon-modified FEVE resin with a solid content of 45%.

[0037] A method for preparing water-based fluorocarbon topcoat for metal products includes the following steps:

[0038] The nanofiller and dispersing agent were added to 3 kg of deionized water and dispersed until uniform using a high-speed disperser. The mixture was then ground until the particle size was ≤50 μm to obtain a nanofiller dispersion.

[0039] Aqueous FEVE fluorocarbon resin, silicone-modified FEVE resin, and perfluorodecyl ethyl acrylate were added to a stirred tank and stirred at 700 rpm to obtain a resin system.

[0040] While stirring, dipropylene glycol methyl ether and hydroxymethyl propyl cellulose were added to the resin system and stirred until homogeneous. When the viscosity of the system stabilized, the nanofiller dispersion was added dropwise. After the addition was complete, stirring was continued, and silica sol was added. The mixture was stirred at 1000 rpm for 20 minutes to obtain the hybrid network system.

[0041] Add leveling agent and waterborne polyisocyanate crosslinking agent while stirring at 500 rpm. Continue stirring for 5 minutes, then stop stirring. Pass the mixture through a 100-mesh filter to remove solids and insoluble matter. Adjust the solid content of the system to 45% with deionized water to obtain waterborne fluorocarbon topcoat for metal products.

[0042] Example 2

[0043] The only difference between this embodiment and Embodiment 1 is that the water-based fluorocarbon topcoat for metal products includes the following raw materials: 24 kg of water-based FEVE fluorocarbon resin, 8 kg of silicone-modified FEVE resin, 7 kg of perfluorodecyl ethyl acrylate, 15 kg of nanofiller, 10 kg of silica sol, 0.5 kg of hydroxymethyl propyl cellulose, 1.6 kg of dipropylene glycol methyl ether, 2 kg of water-based polyisocyanate crosslinking agent, 0.5 kg of leveling agent, and 0.3 kg of dispersing agent.

[0044] Example 3

[0045] The only difference between this embodiment and Embodiment 1 is that the water-based fluorocarbon topcoat for metal products includes the following raw materials: 28 kg of water-based FEVE fluorocarbon resin, 6 kg of silicone-modified FEVE resin, 5 kg of perfluorodecyl ethyl acrylate, 12 kg of nanofiller; 8 kg of silica sol, 0.3 kg of hydroxymethyl propyl cellulose, 1.2 kg of dipropylene glycol methyl ether, 1.5 kg of water-based polyisocyanate crosslinking agent, 0.3 kg of leveling agent, and 0.2 kg of dispersant.

[0046] Example 4

[0047] The only difference between this embodiment and Embodiment 1 is that the nanofiller in this embodiment includes nano-titanium dioxide, zirconium phosphate and hydrophobic fumed silica in a weight ratio of 4:3:4.

[0048] Example 5

[0049] The only difference between this embodiment and Embodiment 1 is that the nanofiller in this embodiment includes nano-titanium dioxide, zirconium phosphate and hydrophobic fumed silica in a weight ratio of 4.5:3.5:3.5.

[0050] Example 6

[0051] The only difference between this embodiment and Embodiment 1 is that the nanofiller in this embodiment includes nano-titanium dioxide, zirconium phosphate and hydrophobic fumed silica in a weight ratio of 5:4:3.

[0052] Example 7

[0053] The only difference between this embodiment and Embodiment 1 is that the leveling agent in this embodiment is polyether-modified polysiloxane.

[0054] Example 8

[0055] The only difference between this embodiment and Example 1 is that the dispersant in this embodiment is a fluorocarbon chain modified acrylate.

[0056] Example 9

[0057] The only difference between this embodiment and Example 1 is that the preparation method of the organosilicon-modified FEVE resin includes the following steps:

[0058] At 40°C, 50 kg of water-based FEVE fluorocarbon resin was added to 40 kg of propylene glycol methyl ether acetate to form a homogeneous solution.

[0059] Lower the temperature to 30℃, and add 6.5 kg of silane coupling agent KH-560 dropwise while stirring. After the addition is complete, add 0.2 kg of dibutyltin dilaurate catalyst and continue stirring for 20 min.

[0060] The temperature was raised to 70°C and stirred continuously for 6 hours. Then the mixture was allowed to cool to room temperature, filtered to remove insoluble matter or impurities, and some organic solvent was removed by vacuum distillation to obtain organosilicon-modified FEVE resin with a solid content of 40%.

[0061] Example 10

[0062] The only difference between this embodiment and Example 1 is that the preparation method of the organosilicon-modified FEVE resin includes the following steps:

[0063] At 50°C, 50 kg of water-based FEVE fluorocarbon resin was added to 40 kg of propylene glycol methyl ether acetate to form a homogeneous solution.

[0064] The temperature was lowered to 35°C, and 6.5 kg of silane coupling agent KH-560 was added dropwise while stirring. After the addition was complete, 0.2 kg of dibutyltin dilaurate catalyst was added, and stirring was continued for 15 min.

[0065] The temperature was raised to 80°C and stirred continuously for 4 hours. Then the mixture was allowed to cool to room temperature, filtered to remove insoluble matter or impurities, and some organic solvent was removed by vacuum distillation to obtain organosilicon-modified FEVE resin with a solid content of 50%.

[0066] Example 11

[0067] The only difference between this embodiment and Embodiment 1 is that in the preparation method of the waterborne fluorocarbon topcoat for metal products in this embodiment, a leveling agent and a waterborne polyisocyanate crosslinking agent are added under stirring at 500 rpm. After stirring for another 5 minutes, stirring is stopped, and the mixture is passed through a 100-mesh filter to remove solids and insoluble matter. The solid content of the system is adjusted to 43% with deionized water to obtain the waterborne fluorocarbon topcoat for metal products.

[0068] Example 12

[0069] The only difference between this embodiment and Embodiment 1 is that in the preparation method of the waterborne fluorocarbon topcoat for metal products in this embodiment, a leveling agent and a waterborne polyisocyanate crosslinking agent are added under stirring at 500 rpm. After stirring for another 5 minutes, stirring is stopped, and the mixture is passed through a 100-mesh filter to remove solids and insoluble matter. The solid content of the system is adjusted to 47% with deionized water to obtain the waterborne fluorocarbon topcoat for metal products.

[0070] Example 13

[0071] The only difference between this embodiment and Embodiment 1 is that the water-based fluorocarbon topcoat for metal products in this embodiment includes the following raw materials: 26 kg of water-based FEVE fluorocarbon resin, 7 kg of silicone-modified FEVE resin, 6.5 kg of perfluorodecyl ethyl acrylate, 13.5 kg of nanofiller; 9 kg of silica sol, 0.4 kg of hydroxymethyl propyl cellulose, 1.4 kg of dipropylene glycol methyl ether, 1.75 kg of water-based polyisocyanate crosslinking agent, 0.4 kg of leveling agent, 0.25 kg of dispersing agent, and 2 kg of PTFE micro powder.

[0072] In the preparation method of waterborne fluorocarbon topcoat for metal products in this embodiment: PTFE micro powder, leveling agent and waterborne polyisocyanate crosslinking agent are added under stirring at 500 rpm. After stirring for 5 minutes, stirring is stopped. The mixture is passed through a 100-mesh filter to remove solids and insoluble matter. The solid content of the system is adjusted to 45% with deionized water to obtain waterborne fluorocarbon topcoat for metal products.

[0073] Example 14

[0074] The difference between this embodiment and Embodiment 1 lies only in that the waterborne fluorocarbon topcoat for metal products in this embodiment comprises the following raw materials: 26 kg of waterborne FEVE fluorocarbon resin, 7 kg of silicone-modified FEVE resin, 6.5 kg of perfluorodecyl ethyl acrylate, 13.5 kg of nanofiller; 9 kg of silica sol, 0.4 kg of hydroxymethyl propyl cellulose, 1.4 kg of dipropylene glycol methyl ether, 1.75 kg of waterborne polyisocyanate crosslinking agent, 0.4 kg of leveling agent, 0.25 kg of dispersing agent, and 2 kg of PTFE micro powder. The nanofiller in this embodiment comprises nano-titanium dioxide, zirconium phosphate, and hydrophobic fumed silica in a weight ratio of 4.5:3.5:3.5. The dispersing agent is fluorocarbon chain modified acrylate.

[0075] A method for preparing water-based fluorocarbon topcoat for metal products includes the following steps:

[0076] The nanofiller and dispersing agent were added to 3 kg of deionized water and dispersed until uniform using a high-speed disperser. The mixture was then ground until the particle size was ≤50 μm to obtain a nanofiller dispersion.

[0077] Aqueous FEVE fluorocarbon resin, silicone-modified FEVE resin, and perfluorodecyl ethyl acrylate were added to a stirred tank and stirred at 700 rpm to obtain a resin system.

[0078] While stirring, dipropylene glycol methyl ether and hydroxymethyl propyl cellulose were added to the resin system and stirred until homogeneous. When the viscosity of the system stabilized, the nanofiller dispersion was added dropwise. After the addition was complete, stirring was continued, and silica sol was added. The mixture was stirred at 1000 rpm for 20 minutes to obtain the hybrid network system.

[0079] PTFE micro powder, leveling agent and waterborne polyisocyanate crosslinking agent are added under stirring at 500 rpm. After stirring for 5 minutes, stirring is stopped. The mixture is passed through a 100-mesh filter to remove solids and insoluble matter. The solid content of the system is adjusted to 45% with deionized water to obtain waterborne fluorocarbon topcoat for metal products.

[0080] Comparative Example

[0081] Comparative Example 1

[0082] The only difference between this comparative example and Example 1 is that an equal amount of waterborne FEVE fluorocarbon resin is used to replace the silicone-modified FEVE resin.

[0083] Comparative Example 2

[0084] The only difference between this comparative example and Example 1 is that an equal amount of waterborne FEVE fluorocarbon resin is used instead of perfluorodecyl ethyl acrylate.

[0085] Comparative Example 3

[0086] The only difference between this comparative example and Example 1 is that an equal amount of water-based FEVE fluorocarbon resin is used to replace the silica sol.

[0087] Comparative Example 4

[0088] The only difference between this comparative example and Example 1 is that the water-based fluorocarbon topcoat for metal products does not contain hydroxymethylpropyl cellulose.

[0089] Comparative Example 5

[0090] The only difference between this comparative example and Example 1 is that the water-based fluorocarbon topcoat for metal products does not contain dipropylene glycol methyl ether.

[0091] Comparative Example 6

[0092] The only difference between this comparative example and Example 1 is that the waterborne fluorocarbon topcoat for metal products does not contain a waterborne polyisocyanate crosslinking agent.

[0093] Performance testing

[0094] The following performance tests were conducted on Examples 1-14 and Comparative Examples 1-6:

[0095] High-temperature anti-adhesion (180℃, peel force) test: According to GB / T2792-2014 "Test method for peel strength of adhesive tape", the peel force of water-based fluorocarbon topcoat on metal products at 180℃ was tested.

[0096] Temperature resistance (long-term use): According to GB / T1735-2009 "Determination of heat resistance of paints and varnishes", the peel strength of water-based fluorocarbon topcoat on metal products under long-term aging at 180℃ for 2000h was tested.

[0097] Hydrophobicity test: The water contact angle of water-based fluorocarbon topcoat on metal products was tested according to the contact angle test method in Appendix C of GB / T30447-2013 "Pre-coated decorative aluminum panels for building".

[0098] The test results are shown in Table 1.

[0099] Table 1

[0100]

[0101] Combining Example 1 and Comparative Examples 1-6 with Table 1, it can be seen that compared to Example 1, the peel force at 180℃ and the peel force after aging at 180℃ for 2000 hours in Comparative Examples 1-4 both increased. The peel force at 180℃ in Comparative Example 5 did not change significantly, but increased significantly. The peel force at 180℃ in Comparative Example 6 decreased, but increased significantly. The water contact angles in Comparative Examples 1-6 all decreased significantly and were all less than 150°. Further comparison shows that the difference between the peel force after aging at 180℃ for 2000 hours and the peel force at 180℃ in Comparative Examples 1-6 was significantly greater than the difference in Example 1. This indicates that using the raw material ratio and preparation method of Example 1 can reduce the viscosity of water-based fluorocarbon topcoat on metal products at 180℃, improve the surface hydrophobicity of the water-based fluorocarbon topcoat on metal products, and reduce the variation in viscosity of the water-based fluorocarbon topcoat on metal products after long-term aging at 180℃. Therefore, the water-based fluorocarbon topcoat for metal products of this application has excellent high-temperature anti-sticking and self-cleaning properties.

[0102] This is likely because the low surface energy of waterborne FEVE fluorocarbon resin imparts basic anti-sticking and hydrophobic properties to the coating. The organosilicon-modified FEVE resin grafted onto the FEVE backbone retains the low surface energy of the fluorocarbon chain while enhancing high-temperature structural stability through silicon-oxygen segments, preventing increased stickiness due to softening at high temperatures. Perfluorodecyl ethyl acrylate contains long-chain perfluoroalkyl groups, exhibiting excellent compatibility with the fluorocarbon chain of FEVE and the silicon-oxygen segments of the organosilicon-modified resin. During resin mixing, it is uniformly dispersed in the continuous resin phase and eventually enriched on the coating surface, forming a "fluorine-silicon" composite low surface energy layer, further reducing the critical surface tension at high temperatures and enhancing anti-sticking properties. Silica sol reacts with the resin system under stirring, constructing an "organic resin-inorganic silicon" hybrid network. This improves coating hardness and enhances its resistance to deformation at high temperatures, reducing the penetration and adhesion of sticky substances at high temperatures. A water-based polyisocyanate crosslinking agent reacts with the hydroxyl groups in FEVE and silicone-modified FEVE to form a three-dimensional crosslinking structure, which makes the coating remain rigid at 180°C, reducing the increase in stickiness caused by softening, thus providing long-term anti-sticking and self-cleaning properties.

[0103] As can be seen from Examples 1-14 and Table 1, the peel force at 180℃ in Examples 1-14 is less than 0.3 N / cm, the peel force after aging at 180℃ for 2000 h is less than 0.45 N / cm, and the water contact angle is greater than 150°. This indicates that waterborne fluorocarbon topcoats for metal products with excellent high-temperature anti-sticking and self-cleaning properties can be prepared using the raw material ratios and preparation methods within the range of Examples 1-14.

[0104] Furthermore, comparative data shows that, compared to Example 1, the peel strength at 180°C and the peel strength after aging at 180°C for 2000 hours are significantly lower in Examples 4-6 and 13-14, and the water contact angle is larger. This indicates that using the raw material ratios and preparation methods of Examples 4-6 and 13-14 helps to further improve the excellent high-temperature anti-sticking and self-cleaning properties of water-based fluorocarbon topcoats for metal products.

[0105] 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 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. A water-based fluorocarbon finish for metal products, characterized by, The raw materials include the following parts by weight: 24-28 parts of waterborne FEVE fluorocarbon resin, 6-8 parts of silicone-modified FEVE resin, 5-7 parts of perfluorodecyl ethyl acrylate, 12-15 parts of nanofiller; 8-10 parts of silica sol, 0.3-0.5 parts of hydroxymethyl propyl cellulose, 1.2-1.6 parts of dipropylene glycol methyl ether, 1.5-2 parts of waterborne polyisocyanate crosslinking agent, 0.3-0.5 parts of leveling agent, and 0.2-0.3 parts of dispersing agent; the silicone-modified FEVE resin is prepared according to the following steps: At 40-50℃, waterborne FEVE fluorocarbon resin is dissolved in propylene glycol methyl ether acetate to form a homogeneous solution; Lower the temperature to 30-35℃, and add silane coupling agent KH-560 dropwise while stirring. After the addition is complete, add dibutyltin dilaurate catalyst and continue stirring for 15-20 minutes. Heat to 70-80℃, stir continuously for 4-6 hours, cool to room temperature, filter to remove insoluble matter or impurities, and remove part of the organic solvent by vacuum distillation to obtain organosilicon-modified FEVE resin with a solid content of 40-50%.

2. The water-based fluorocarbon finish for metal products according to claim 1, characterized by, The nanofiller comprises nano-titanium dioxide, zirconium phosphate and hydrophobic fumed silica in a weight ratio of (4-5):(3-4):(3-4).

3. The water-based fluorocarbon finish for metal products according to claim 1, characterized by, The solid content of the water-based fluorocarbon topcoat for the metal products is 43-47%.

4. The water-based fluorocarbon finish for metal products according to claim 1, characterized by, The leveling agent is a polyether-modified polysiloxane or a fluorinated polyether siloxane.

5. The water-based fluorocarbon topcoat for metal products according to claim 1, characterized in that, The dispersing agent is a fluorocarbon chain modified acrylate.

6. The water-based fluorocarbon finish for metal products according to claim 1, characterized by It also includes PTFE micro powder.

7. A method for preparing a water-based fluorocarbon topcoat for metal products according to any one of claims 1 to 6, characterized in that, Includes the following steps: According to the above ratio, add the nanofiller and dispersing agent to deionized water, disperse evenly, and grind until the particle size is ≤50μm to obtain the nanofiller dispersion. A waterborne FEVE fluorocarbon resin, an organosilicon-modified FEVE resin, and perfluorodecyl ethyl acrylate were mixed evenly to obtain a resin system. While stirring, dipropylene glycol methyl ether and hydroxymethyl propyl cellulose were added to the resin system and stirred until homogeneous. The viscosity of the system was monitored in real time during the stirring process. When the viscosity of the system was stable, the nanofiller dispersion was added dropwise while stirring. After the addition was completed, silica sol was added and stirred until homogeneous to obtain the hybrid network system. Add leveling agent and water-based polyisocyanate crosslinking agent while stirring. After stirring evenly, filter to obtain water-based fluorocarbon topcoat for metal products.

8. The method of preparing a water-based fluorocarbon finish for metal products according to claim 7, characterized by, PTFE micro powder, leveling agent and water-based polyisocyanate crosslinking agent are added under stirring. After stirring evenly, the mixture is filtered to obtain water-based fluorocarbon topcoat for metal products.

9. The method of preparing a water-based fluorocarbon finish for metal products according to claim 8, characterized by, After filtration, the solid content of the system is adjusted to 43-47% with deionized water to obtain a water-based fluorocarbon topcoat for metal products.

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