Fluorinated silicone-modified waterborne polyurethane coatings and methods of making the same

Abstract

The present disclosure provides a fluorinated organic silicon modified waterborne polyurethane coating and a preparation method thereof, and belongs to the technical field of port power protection coating. The preparation method comprises the following steps: mixing diisocyanate, oligomeric diol and hydrophilic monomer, adding a catalyst after heating treatment, and stirring to obtain a polyurethane prepolymer; adding a neutralizing agent to the polyurethane prepolymer, stirring uniformly, and obtaining a neutralized prepolymer; adding deionized water to the neutralized prepolymer, shearing and dispersing, and standing to obtain a uniformly dispersed prepolymer; adding fluorinated organic silicon to the uniformly dispersed prepolymer, stirring and reacting, adding a chain extender, and stirring and reacting to obtain a fluorinated organic silicon modified waterborne polyurethane emulsion; coating the fluorinated organic silicon modified waterborne polyurethane emulsion into a mold, drying, and obtaining a fluorinated organic silicon modified waterborne polyurethane coating film, so as to endow the waterborne polyurethane coating with weather resistance and aging resistance in a high-humidity and high-temperature, high-ultraviolet environment of a coastal port.

Description

Technical Field

[0001] This disclosure belongs to the field of port power protection coating technology, specifically relating to a fluorinated organosilicon modified waterborne polyurethane coating and its preparation method. Background Technology

[0002] Coastal port areas present unique environmental challenges to coating performance. High humidity and high moisture content in the air easily lead to rust and corrosion of metallic materials, and swelling and deformation of non-metallic materials due to water absorption. Simultaneously, high temperatures accelerate chemical reactions, speeding up coating aging and reducing its lifespan. Furthermore, the long-term exposure to strong ultraviolet radiation in coastal ports damages the coating's molecular structure, causing discoloration, chalking, and peeling, severely impacting both protective performance and aesthetics.

[0003] Traditional coatings have several shortcomings in the high-humidity, high-temperature, and high-UV environment of coastal ports. Firstly, ordinary coatings have poor water resistance, easily absorbing moisture in high-humidity environments, leading to decreased adhesion between the coating and the substrate, resulting in blistering and peeling. Secondly, their heat resistance is limited; under high-temperature conditions, the coating's hardness and strength decrease, and its abrasion resistance and scratch resistance deteriorate. Furthermore, existing coatings lack sufficient UV resistance; prolonged exposure to UV radiation causes surface aging and gradual performance degradation. In addition, many traditional coatings contain organic solvents, causing environmental pollution and failing to meet environmental protection requirements. Summary of the Invention

[0004] This disclosure aims to at least solve one of the technical problems existing in the prior art, and to provide a fluorinated organosilicon-modified waterborne polyurethane coating and its preparation method.

[0005] One aspect of this disclosure provides a method for preparing a fluorinated organosilicon-modified waterborne polyurethane coating, the method comprising: S110. Diisocyanate, oligomeric diol and hydrophilic monomer are mixed, heated and then a catalyst is added and stirred to react, so as to obtain polyurethane prepolymer. S120. Add a neutralizing agent to the polyurethane prepolymer and stir until uniform to obtain the neutralized prepolymer. S130. Add deionized water to the neutralized prepolymer, and perform shear dispersion under high-speed stirring. After standing, a uniformly dispersed prepolymer is obtained. S140. Fluorinated organosilicon is added to a uniformly dispersed prepolymer, and after stirring and reacting, a chain extender is added and stirred and reacted to obtain a fluorinated organosilicon-modified waterborne polyurethane emulsion. S150. Fluorinated silicone-modified waterborne polyurethane emulsion is coated onto a mold and dried to obtain a fluorinated silicone-modified waterborne polyurethane coating film. Optionally, in step S110, the diisocyanate includes any one of hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, isoflurone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and phenylmethylene diisocyanate. The diisocyanate accounts for 30-40% of the mass fraction in the neutralized prepolymer.

[0006] Optionally, in step S110, the oligomeric diol includes any one of polycarbonate diol, polyhexanediol adipate diol, polybutylene adipate diol, polyethylene glycol butylene adipate diol, polyether diol, and polytetrahydrofuran diol. The oligomeric diol accounts for 35-45% of the mass fraction in the neutralized prepolymer.

[0007] Optionally, in step S110, the hydrophilic monomer includes any one of methoxybenzaldehyde, dimethylolpropionic acid, diethyl methacrylate, N-vinylpyrrolidone, glycidyl methacrylate, trimethylsiloxane-2-methacrylatepropoxysilane, acrylamide, ethyl carboxyacrylate, and propylene carboxyacrylate. The hydrophilic monomer accounts for 6-9% of the mass fraction in the neutralized prepolymer.

[0008] Optionally, in step S110, the catalyst is selected as dibutyltin dilaurate; The heat treatment is carried out using water bath heating; among which, The water bath heating temperature is 75-85℃, the stirring speed is 400-600rpm, and the stirring time is 3-5h.

[0009] Optionally, in step S120, the neutralizing agent comprises 3-6% by mass in the neutralized prepolymer; The neutralizing agent is selected from any one of triethylamine, dimethylethanolamine, diethylethanolamine, and 2-amino-2-methylpropanol; The stirring speed is 600-800 rpm, and the time is 0.5-1.5 h.

[0010] Optionally, in step S130, the content of deionized water is 75-85% of the total system content; The high-speed stirring temperature is 65-75℃, the stirring speed is 1500-2000rpm, and the stirring time is 1.5-2.5h.

[0011] Optionally, in step S140, the fluorinated organosilicon accounts for 20-28% of the total mass fraction of the system, and the fluorinated organosilicon is selected as tridecafluorooctyltrimethoxysilane; The temperature for adding fluorinated organosilicon to the uniformly dispersed prepolymer and stirring is 50-80℃, the stirring speed is 500-800rpm, and the stirring time is 4-6h.

[0012] Optionally, in step S140, the chain extender has a mass fraction of 6-8% in the neutralized prepolymer, and the chain extender is selected as ethylenediamine; The reaction time after adding the chain extender is 2-4 hours.

[0013] In another aspect of this disclosure, a fluorinated organosilicon-modified waterborne polyurethane coating is provided, wherein the fluorinated organosilicon-modified waterborne polyurethane coating is prepared according to the preparation method described above.

[0014] This disclosure discloses a fluorinated organosilicon-modified waterborne polyurethane coating and its preparation method. The preparation method includes: S110, mixing diisocyanate, oligomeric diol and hydrophilic monomer, heating and then adding a catalyst and stirring to obtain a polyurethane prepolymer; S120, adding a neutralizing agent to the polyurethane prepolymer and stirring evenly to obtain a neutralized prepolymer; S130, adding deionized water to the neutralized prepolymer, shearing and dispersing under high-speed stirring, and allowing it to stand to obtain a uniformly dispersed prepolymer; S140, adding fluorinated organosilicon to the uniformly dispersed prepolymer, stirring and reacting, and then adding a chain extender and stirring to obtain a fluorinated organosilicon-modified waterborne polyurethane emulsion; S150, coating the fluorinated organosilicon-modified waterborne polyurethane emulsion into a mold and drying it to obtain a fluorinated organosilicon-modified waterborne polyurethane coating film. This disclosure modifies waterborne polyurethane with fluorinated organosilanes, which possess high heat resistance, chemical stability, and low surface free energy, while also exhibiting UV resistance, abrasion resistance, and hydrophobicity. Fluorine and silicon elements are introduced into the polyurethane macromolecular chain structure, endowing the waterborne polyurethane coating with excellent weather resistance and aging resistance in the high humidity and high UV environment of coastal ports. This effectively improves the coating's oxidation resistance and extends its service life. It solves the problems of poor stability and short service life of existing externally sourced UV-resistant coatings in the harsh environment of coastal ports, reducing the frequency and cost of maintenance for critical power plant equipment and improving economic efficiency. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the preparation method of the fluorinated organosilicon-modified waterborne polyurethane coating according to a specific embodiment of this disclosure. Figure 2 This is a comparison diagram of the particle size of polyurethane emulsions in various embodiments of this disclosure; Figure 3 This is a comparison diagram of the contact angle of the polyurethane latex film before and after ultraviolet irradiation in various embodiments of this disclosure; Figure 4These are comparison images of the gloss of polyurethane latex films before and after ultraviolet irradiation in various embodiments of this disclosure; wherein, Figure 4 In the figure, a represents the contact angle of latex films with different tridecafluorooctyltrimethoxysilane contents without UV irradiation, and b represents the contact angle of latex films with different tridecafluorooctyltrimethoxysilane contents after 10 min of UV irradiation in the accelerated aging test. Figure 5 This is a comparison chart of the ultraviolet transmittance of polyurethane films with different modified organosilicon contents in various embodiments of this disclosure. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0017] As shown in Figure 1, one aspect of this disclosure provides a method S100 for preparing a fluorinated organosilicon-modified waterborne polyurethane coating, specifically including the following steps S110~S150: S110. Add diisocyanate, oligomeric diol and hydrophilic monomer to a three-necked flask, adjust the temperature of the water bath, and after the isocyanate, oligomeric diol and hydrophilic monomer are evenly mixed, add catalyst to the three-necked flask and start the reaction by stirring at a constant speed. Adjust the stirring speed to obtain polyurethane prepolymer.

[0018] In step S110, the heating treatment is performed using a water bath, wherein the water bath temperature is set to 75-85℃. In some specific embodiments, the water bath temperature can be set to 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, or 85℃. Preferably, the heating temperature of the water bath is adjusted to 80℃.

[0019] In step S110, the rotor stirring speed is set to 400-600 rpm. In some specific embodiments, the rotor stirring speed is set to 400 rpm, 450 rpm, 500 rpm, 550 rpm, or 600 rpm. Preferably, in this embodiment, the rotor stirring speed is set to 500 rpm in step S110.

[0020] In step S110, the stirring time is 3-5 hours. In some specific embodiments, the stirring time can preferably be 3 hours, 4 hours, or 5 hours. Preferably, the stirring time is set to 3 hours.

[0021] In step S110, the diisocyanate may be any one of hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isoflurane diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (HMDI), and phenyl diisocyanate (XDI). In a specific embodiment of the present invention, hexamethylene diisocyanate (HDI) is preferred. Furthermore, the mass fraction of the diisocyanate in the neutralized prepolymer is 30-40%. It should be noted that the prepolymer here refers to the system after neutralization without the addition of deionized water; that is, the neutralized prepolymer here is the prepolymer obtained in step S120.

[0022] In step S110, the oligomeric diol includes, but is not limited to, any one of polycarbonate diol (PCDL), polyhexyl adipate diol (PHA), polybutylene adipate diol (PBA), polyethylene glycol butylene adipate diol (ODX-218), polyether diol 220 (PPG), and polytetrahydrofuran diol (PTMG). In a specific embodiment of the present invention, polycarbonate diol is preferably preferred. Furthermore, the mass fraction of the oligomeric diol in the neutralized prepolymer is 35-45%. Similarly, the neutralized prepolymer here refers to the system after the neutralization reaction without the addition of deionized water; that is, the neutralized prepolymer here is the prepolymer obtained in step S120.

[0023] In step S110, the hydrophilic monomer includes, but is not limited to, any one of methoxybenzaldehyde (DMPA), dimethylolpropionic acid, diethyl methacrylate (HEMA), N-vinylpyrrolidone (NVP), glycidyl methacrylate (GM), trimethylsiloxane-2-methacrylate propoxysilane (TRIS), acrylamide, ethyl carboxyacrylate (CE), and propylene carboxyacrylate (CA). In a specific embodiment of the present invention, dimethylolpropionic acid is preferably used as the hydrophilic monomer. Furthermore, the mass fraction of the hydrophilic monomer in the neutralized prepolymer is 6-9%. Similarly, the neutralized prepolymer here refers to the system after the neutralization reaction without the addition of deionized water; that is, the neutralized prepolymer here is the prepolymer obtained in step S120.

[0024] In step S110, the catalyst is selected as dibutyltin dilaurate.

[0025] S120. Add a neutralizing agent to the polyurethane prepolymer, stir evenly, and neutralize the carboxyl groups (anionic type) in the prepolymer to obtain the neutralized prepolymer.

[0026] In step S120, the stirring rate is 600-800 rpm and the time is 0.5-1.5 h. Preferably, the reaction time is set to 1 h.

[0027] It should be understood that the reaction temperature in step S120 is the same as that in step S110, between 75-85°C, for example, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, or 85°C. Preferably, the heating temperature of the water bath is 80°C.

[0028] In step S120, the neutralizing agent accounts for 3-6% of the mass fraction of the neutralized prepolymer. Similarly, the neutralized prepolymer here refers to the system after the neutralization reaction without the addition of deionized water. In other words, the neutralized prepolymer here is the prepolymer obtained in step S120.

[0029] In step S120, the neutralizing agent includes, but is not limited to, triethylamine, dimethylethanolamine (DMEA), diethylethanolamine (DEEA), 2-amino-2-methylpropanol (AMP-95), etc. In a specific embodiment of the present invention, triethylamine is selected as the neutralizing agent.

[0030] S130. Add deionized water to the neutralized prepolymer and shear dispersion under high-speed stirring to make the neutralized prepolymer evenly dispersed in the deionized water. After standing, a uniformly dispersed prepolymer is obtained.

[0031] In step S130, the content of deionized water is 75-85% of the total system content, for example, preferably 80%, the high-speed stirring temperature is 65-75℃, for example, preferably 70℃, the stirring speed is 1500-2000rpm, for example, the stirring rod speed can be adjusted to 1500rpm, and the stirring time is 1.5-2.5h, for example, the stirring time can be preferably 2h.

[0032] It should be noted that the "total system" mentioned in the deionized water content percentage refers to the system in which deionized water has been removed during the preparation of the fluorinated organosilicon modified waterborne polyurethane emulsion system.

[0033] S140. Fluorinated organosilicon is added to the uniformly dispersed prepolymer, and after stirring and reacting, a chain extender is added and stirred and reacted to obtain a fluorinated organosilicon-modified waterborne polyurethane emulsion.

[0034] In step S140, the fluorinated organosilicon accounts for 20-28% of the total system by mass, and the fluorinated organosilicon is selected as tridecafluorooctyltrimethoxysilane. Furthermore, the temperature for adding the fluorinated organosilicon to the uniformly dispersed prepolymer and stirring the reaction is 50-80°C, preferably 65°C; the stirring rate is 500-800 rpm, preferably 500 rpm; and the stirring time is 4-6 hours, preferably 5 hours.

[0035] It should be noted that the "total system" mentioned above refers to the system in which deionized water has been removed after the preparation of the fluorinated organosilicon modified waterborne polyurethane emulsion system.

[0036] In step S140, the chain extender has a mass fraction of 6-8% in the neutralized prepolymer. Similarly, the neutralized prepolymer here refers to the system without the addition of deionized water after the neutralization reaction. That is, the neutralized prepolymer here is the prepolymer obtained in step S120, which does not contain deionized water and fluorinated organosilicon. Secondly, the chain extender is selected as ethylenediamine; and the reaction time after adding the chain extender is 2-4 hours, preferably 3 hours.

[0037] S150. Fluorinated silicone-modified waterborne polyurethane emulsion is coated onto a mold and dried to obtain a fluorinated silicone-modified waterborne polyurethane coating film. It should be noted that step 150 also includes: rinsing and drying the 15×15mm mold with anhydrous ethanol, applying 50ml of fluorinated organosilicon-modified waterborne polyurethane emulsion evenly to the mold, letting it stand in a fume hood to air dry naturally for 3 days, and then transferring it to a 50℃ oven to dry for 24 hours to obtain a fluorinated organosilicon-modified waterborne polyurethane film.

[0038] In this embodiment, waterborne polyurethane is modified with a fluorinated organosilane that has high heat resistance, chemical stability, and low surface free energy, while also possessing UV resistance, abrasion resistance, and hydrophobicity. Fluorine and silicon elements are introduced into the polyurethane macromolecular chain structure, thereby endowing the waterborne polyurethane coating with weather resistance and aging resistance in the high humidity and high UV environment of coastal ports.

[0039] In this embodiment, firstly, waterborne polyurethane is modified with fluorinated organosilicon. The introduction of fluorine and silicon atoms gives the coating a hydrophobic structure, reducing water molecule adsorption and improving water resistance. Specifically, the introduction of fluorinated organosilicon endows the coating with excellent hydrophobic properties, effectively preventing moisture penetration and significantly improving its water resistance and moisture-proof capabilities. Secondly, the high bond energy and stability of the CF and C-Si bonds enhance the chemical and thermal stability of the coating, giving it UV resistance and oxidation resistance, extending its service life. In other words, fluorinated organosilicon has excellent heat resistance, maintaining the coating's stability at high temperatures and preventing softening and deformation. Furthermore, waterborne polyurethane, as the base resin, gives the coating good adhesion and flexibility, allowing it to adapt to different substrate surface morphologies and resisting cracking and peeling under external forces. Simultaneously, this coating uses water as a solvent, contains no organic solvents, is environmentally friendly, and meets environmental protection requirements.

[0040] In another aspect of this disclosure, a fluorinated organosilicon-modified waterborne polyurethane coating is provided. This fluorinated organosilicon-modified waterborne polyurethane coating is prepared according to the preparation method described above. For the specific preparation process, please refer to the description above, which will not be repeated here.

[0041] This disclosure provides a fluorinated silicone-modified waterborne polyurethane coating. Through material structure design, a waterborne polyurethane UV-resistant coating system containing F and Si in its molecular chain is created, avoiding the problem of uneven dispersion of the effective components with the polyurethane matrix. This offers significant advantages in coping with the high humidity, heat, and UV environment of coastal ports. Furthermore, this coating possesses excellent UV resistance, absorbing and reflecting ultraviolet rays to prevent damage to the coating's internal structure and extend its service life. Moreover, the fluorinated silicone-modified waterborne polyurethane coating also exhibits excellent chemical corrosion resistance, resisting erosion from seawater, acid rain, and other corrosive media, providing reliable protection for facilities in coastal ports.

[0042] Compared to the externally-assisted UV-resistant coating technology commonly used in coastal ports, the coating disclosed herein is an intrinsic fluorinated organosilicon-modified waterborne polyurethane UV-resistant coating developed through molecular design. This eliminates the need for external UV additives. On one hand, it reduces migration and loss through UV absorption and direct binding with the resin, ensuring long-term coating use. On the other hand, the molecular structure design allows for uniform distribution of the UV-resistant components within the coating, improving its stability against UV aging. This effectively avoids the problems of short service life and high maintenance frequency associated with current externally-assisted UV coatings.

[0043] The preparation method and specific applications of fluorinated organosilicon-modified waterborne polyurethane coatings will be further illustrated below with reference to specific embodiments: Example 1 Step 1: Fill the water bath with water and heat it to 80°C. Adjust the rotor speed to 500 rpm. Weigh 8g of hexamethylene diisocyanate (HDI), 9g of polycarbonate diol (PCDL), 1.8g of methoxybenzaldehyde (DMPA), and 3 drops of dibutyltin dilaurate (DBTDL). Place them in a three-necked flask, seal it, and stir continuously for 3 hours to obtain a polyurethane prepolymer solution.

[0044] Step 2: Adjust the stirring speed to 800 rpm, keep the water bath heating temperature at 80℃, weigh 1.2g of triethylamine, add it to the polyurethane prepolymer solution, stir for 1 hour to complete the carboxyl neutralization reaction in the prepolymer, and obtain a prepolymer mixture with high viscosity after the reaction.

[0045] Step 3: After the reaction is complete, cool the system to 70°C, increase the stirring speed to 1500 rpm, add 21.5 g of deionized water to the prepolymer mixture with high viscosity, continue stirring and mixing for 2 hours, and after standing, obtain a uniformly mixed polyurethane solution.

[0046] Step 4: Adjust the temperature of the reaction system to 65℃, adjust the rotor speed (stirring speed) to 500 rpm, add 5.38g of tridecafluorooctyltrimethoxysilane to the polyurethane solution, and continue the reaction for 5 hours. Then add 1.5g of ethylenediamine as a chain extender and react with the remaining -NCO groups for 3 hours to complete the chain extension and molecular chain growth, and obtain an aqueous polyurethane emulsion. Step 5: Rinse the 15×15mm mold with anhydrous ethanol and dry it. Apply 50mL of emulsion evenly to the mold and let it stand in a fume hood to air dry naturally for 3 days. Then transfer it to a 50℃ oven to dry for 24 hours to obtain a waterborne polyurethane film modified with fluorinated organosilicon.

[0047] Example 2 Step 1: Fill the water bath with water and heat it to 80°C. Adjust the rotor speed to 500 rpm. Weigh 8g of hexamethylene diisocyanate (HDI), 9g of polycarbonate diol (PCDL), 1.8g of methoxybenzaldehyde (DMPA), and 3 drops of dibutyltin dilaurate (DBTDL). Place them in a three-necked flask, seal it, and stir continuously for 3 hours to obtain a polyurethane prepolymer solution.

[0048] Step 2: Adjust the rotor stirring speed to 800 rpm, weigh 1.2 g of triethylamine, add it to the polyurethane prepolymer solution, and continue stirring at 80°C for 1 h to complete the carboxyl neutralization reaction in the prepolymer. After the reaction, a prepolymer mixture with high viscosity is obtained.

[0049] Step 3: After the reaction is complete, the system temperature is lowered to 70 ℃, the rotor stirring speed is increased to 1500 rpm, and 22.05 g of deionized water is added to the prepolymer mixture with high viscosity. Stirring and mixing are continued for 2 hours. After standing, a uniformly mixed polyurethane solution is obtained. Step 4: The reaction system temperature was lowered to 65℃, the stirring speed was adjusted to 500 rpm, 6.06 g of tridecafluorooctyltrimethoxysilane was added to the polyurethane solution, and the reaction was continued for 5 h. Then, 1.5 g of ethylenediamine was added as a chain extender and reacted with the residual -NCO groups for 3 h to complete the chain extension and molecular chain growth, and the aqueous polyurethane emulsion was obtained. Step 5: Rinse the 15×15mm mold with anhydrous ethanol and dry it. Apply 50ml of emulsion evenly to the mold and let it stand in a fume hood to air dry naturally for 3 days. Then transfer it to a 50℃ oven to dry for 24 hours to obtain a waterborne polyurethane film modified with fluorinated organosilicon.

[0050] Example 3 Step 1: Fill the water bath with water and heat it to 80°C. Adjust the rotor speed to 500 rpm. Weigh 8g of hexamethylene diisocyanate (HDI), 9g of polycarbonate diol (PCDL), 1.8g of methoxybenzaldehyde (DMPA), and 3 drops of dibutyltin dilaurate (DBTDL). Place them in a three-necked flask, seal it, and stir continuously for 3 hours to obtain a polyurethane prepolymer solution.

[0051] Step 2: Adjust the stirring speed to 800 rpm, maintain the water bath heating temperature at 80℃, weigh 1.2g of triethylamine, add it to the polyurethane prepolymer solution, stir for 1 hour to complete the carboxyl neutralization reaction in the prepolymer, and obtain a prepolymer mixture with high viscosity after the reaction.

[0052] Step 3: After the reaction is complete, the system is cooled to 70°C, the rotor stirring speed is increased to 1500 rpm, and 22.63 g of deionized water is added to the mixture. Stirring and mixing is continued for 2 hours. After standing, a uniformly mixed polyurethane solution is obtained.

[0053] Step 4: Adjust the reaction system temperature to 65℃ and the stirring speed to 500rpm. Add 6.79g of tridecafluorooctyltrimethoxysilane to the polyurethane solution and continue the reaction for 5h. Then add 1.5g of ethylenediamine as a chain extender and react with the remaining -NCO groups for 3h to complete the chain extension and molecular chain growth, and obtain the waterborne polyurethane emulsion.

[0054] Step 5: Rinse the 15×15mm mold with anhydrous ethanol and dry it. Apply 50ml of emulsion evenly to the mold and let it stand in a fume hood to air dry naturally for 3 days. Then transfer it to a 50℃ oven to dry for 24 hours to obtain a waterborne polyurethane film modified with fluorinated organosilicon.

[0055] Example 4 Step 1: Fill the water bath with water and heat it to 80°C. Adjust the rotor speed to 500 rpm. Weigh 8g of hexamethylene diisocyanate (HDI), 9g of polycarbonate diol (PCDL), 1.8g of methoxybenzaldehyde (DMPA), and 3 drops of dibutyltin dilaurate (DBTDL). Place them in a three-necked flask, seal it, and stir continuously for 3 hours to obtain a polyurethane prepolymer solution.

[0056] Step 2: Adjust the rotor stirring speed to 800 rpm, maintain the water bath heating temperature at 80℃, weigh 1.2g of triethylamine, add it to the polyurethane prepolymer solution, stir for 1 hour to complete the carboxyl neutralization reaction in the prepolymer, and obtain a prepolymer mixture with high viscosity after the reaction.

[0057] Step 3: After the reaction is complete, the system is cooled to 70°C, the rotor stirring speed is increased to 1500 rpm, and 23.24 g of deionized water is added to the prepolymer mixture with high viscosity. Stirring and mixing are continued for 2 hours. After standing, a uniformly mixed polyurethane solution is obtained.

[0058] Step 4: Reduce the temperature of the reaction system to 65℃, adjust the rotor stirring speed to 500rpm, add 7.55g of tridecafluorooctyltrimethoxysilane to the polyurethane solution, and continue the reaction for 5h. Then add 1.5g of ethylenediamine as a chain extender and react with the remaining -NCO groups for 3h to complete the chain extension and molecular chain growth, and obtain the waterborne polyurethane emulsion.

[0059] Step 5: Rinse the 15×15mm mold with anhydrous ethanol and dry it. Apply 50ml of emulsion evenly to the mold and let it stand in a fume hood to air dry naturally for 3 days. Then transfer it to a 50℃ oven to dry for 24 hours to obtain a waterborne polyurethane film modified with fluorinated organosilicon.

[0060] Example 5 Step 1: Fill the water bath with water and heat it to 80°C. Adjust the rotor speed to 500 rpm. Weigh 8g of hexamethylene diisocyanate (HDI), 9g of polycarbonate diol (PCDL), 1.8g of methoxybenzaldehyde (DMPA), and 3 drops of dibutyltin dilaurate (DBTDL). Place them in a three-necked flask, seal it, and stir continuously for 3 hours to obtain a polyurethane prepolymer solution.

[0061] Step 2: Adjust the rotor stirring speed to 800 rpm, maintain the water bath temperature at 80℃, weigh 1.2g of triethylamine, add it to the polyurethane prepolymer solution, stir for 1 hour to complete the carboxyl neutralization reaction in the prepolymer, and obtain a prepolymer mixture with high viscosity after the reaction.

[0062] Step 3: After the reaction is complete, the system is cooled to 70°C, the rotor stirring speed is increased to 1500 rpm, and 23.89 g of deionized water is added to the mixture. Stirring and mixing is continued for 2 hours. After standing, a uniformly mixed polyurethane solution is obtained.

[0063] Step 4: Adjust the reaction system temperature to 65℃ and the stirring speed to 500rpm. Add 8.36g of tridecafluorooctyltrimethoxysilane to the polyurethane solution and continue the reaction for 5h. Then add 1.5g of ethylenediamine as a chain extender and react with the remaining -NCO groups for 3h to complete the chain extension and molecular chain growth, and obtain the waterborne polyurethane emulsion.

[0064] Step 5: Rinse the 15×15mm mold with anhydrous ethanol and dry it. Apply 50mL of emulsion evenly to the mold and let it stand in a fume hood to air dry naturally for 3 days. Then transfer it to a 50℃ oven to dry for 24 hours to obtain a waterborne polyurethane film modified with fluorinated organosilicon.

[0065] like Figure 2 As shown, this disclosure also includes particle size testing of the polyurethane emulsions prepared in Examples 1 to 5. Figure 2 As can be seen, with the introduction of tridecafluorooctyltrimethoxysilane, the particle size distribution is uniform and remains below 200 nm, indicating good emulsion stability. The emulsion particle size continues to increase because the degree of intermolecular entanglement increases with the addition of tridecafluorooctyltrimethoxysilane as Si-O bonds are introduced.

[0066] like Figure 3 As shown, this disclosure presents contact angle tests on the polyurethane films prepared in Examples 1 to 5. The results show that the contact angle of the films is improved to varying degrees after the introduction of tridecafluorooctyltrimethoxysilane. Furthermore, without other variables, the contact angle of the films initially increases and then decreases with the content of tridecafluorooctyltrimethoxysilane. The contact angle reaches its maximum value of 109.7° when the content of tridecafluorooctyltrimethoxysilane reaches 6%, at which point the latex film exhibits the best hydrophobicity. This is because the increase in Si-O segment content leads to an increase in hydrophobic segments in the molecular chain, which migrate to the latex film surface, causing the contact angle of the latex film to gradually increase and the surface energy to decrease. However, once the siloxane content reaches a certain value, the aggregation of silicon segments hinders the migration of fluorine to the surface, resulting in a decreasing contact angle.

[0067] like Figure 4 As shown, this disclosure compares the contact angles of the polyurethane coatings obtained in Examples 1 to 5 before and after ultraviolet irradiation. Figure 4In Figure a, the contact angle of latex films with different tridecafluorooctyltrimethoxysilane contents without UV irradiation is shown. In Figure b, the contact angle of latex films with different tridecafluorooctyltrimethoxysilane contents after 10 minutes of UV irradiation in the accelerated aging experiment is shown. The results indicate that the contact angle of the latex films decreased to varying degrees after UV irradiation in the accelerated aging experiment. This is because UV irradiation causes aging and damage to the surface of the latex films, making the surface rougher.

[0068] like Figure 5 As shown in the comparison of gloss of modified polyurethane latex films before and after ultraviolet irradiation in Examples 1 to 5, the gloss of the latex films was improved to varying degrees after the introduction of tridecafluorooctyltrimethoxysilane, indicating that the anti-ultraviolet performance of the latex film is improved after the introduction of silicon. This is because the Si-O bond has antioxidant properties, and its migration to the surface increases the anti-ultraviolet ability of the latex film.

[0069] This disclosure proposes a fluorinated organosilicon-modified waterborne polyurethane coating and its preparation method, which has the following advantages over the prior art: This disclosure modifies waterborne polyurethane with fluorinated organosilicon to introduce fluorine and silicon atoms into the polyurethane macromolecular chain structure, so that the polyurethane matrix itself has anti-ultraviolet aging properties, effectively improves the oxidation resistance of the coating and extends the service life of the coating, reduces the number of maintenance times and costs of key equipment in power plants, and improves economic benefits.

[0070] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for preparing a fluorinated organosilicon-modified waterborne polyurethane coating, characterized in that, The preparation method includes: S110. Diisocyanate, oligomeric diol and hydrophilic monomer are mixed, heated and then a catalyst is added and stirred to react, so as to obtain polyurethane prepolymer. S120. Add a neutralizing agent to the polyurethane prepolymer and stir until uniform to obtain the neutralized prepolymer. S130. Add deionized water to the neutralized prepolymer, and shear dispersion is carried out under high-speed stirring. After standing, a uniformly dispersed prepolymer is obtained. S140. Fluorinated organosilicon is added to a uniformly dispersed prepolymer, and after stirring and reacting, a chain extender is added and stirred and reacted to obtain a fluorinated organosilicon-modified waterborne polyurethane emulsion. S150. Fluorinated silicone-modified waterborne polyurethane emulsion is coated onto a mold and dried to obtain a fluorinated silicone-modified waterborne polyurethane coating film.

2. The preparation method according to claim 1, characterized in that, In step S110, the diisocyanate includes any one of hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, isoflurone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and phenylmethylene diisocyanate. The diisocyanate accounts for 30-40% of the mass fraction in the neutralized prepolymer.

3. The preparation method according to claim 1, characterized in that, In step S110, the oligomeric diol includes any one of polycarbonate diol, polyhexanediol adipate diol, polybutylene adipate diol, polyethylene glycol butylene adipate diol, polyether diol, and polytetrahydrofuran diol. The oligomeric diol accounts for 35-45% of the mass fraction in the neutralized prepolymer.

4. The preparation method according to claim 1, characterized in that, In step S110, the hydrophilic monomer includes any one of methoxybenzaldehyde, dimethylolpropionic acid, diethyl methacrylate, N-vinylpyrrolidone, glycidyl methacrylate, trimethylsiloxane-2-methacrylatepropoxysilane, acrylamide, ethyl carboxyacrylate, and propylene carboxyacrylate. The hydrophilic monomer accounts for 6-9% of the mass fraction in the neutralized prepolymer.

5. The preparation method according to claim 1, characterized in that, In step S110, the catalyst is selected as dibutyltin dilaurate; The heat treatment is carried out using water bath heating; among which, The water bath heating temperature is 75-85℃, the stirring speed is 400-600rpm, and the stirring time is 3-5h.

6. The preparation method according to claim 1, characterized in that, In step S120, the neutralizing agent constitutes 3-6% by mass in the neutralized prepolymer; The neutralizing agent is selected from any one of triethylamine, dimethylethanolamine, diethylethanolamine, and 2-amino-2-methylpropanol; The stirring speed is 600-800 rpm, and the time is 0.5-1.5 h.

7. The preparation method according to claim 1, characterized in that, In step S130, the content of deionized water is 75-85% of the total system content; The high-speed stirring temperature is 65-75℃, the stirring speed is 1500-2000rpm, and the stirring time is 1.5-2.5h.

8. The preparation method according to claim 1, characterized in that, In step S140, the fluorinated organosilicon accounts for 20-28% of the total mass fraction in the system, and the fluorinated organosilicon is selected as tridecafluorooctyltrimethoxysilane; Fluorinated organosilicon was added to the uniformly dispersed prepolymer at a temperature of 50-80℃, a stirring rate of 500-800 rpm, and a stirring time of 4-6 h.

9. The preparation method according to claim 1, characterized in that, In step S140, the chain extender has a mass fraction of 6-8% in the neutralized prepolymer (excluding deionized water and fluorinated organosilicon), and the chain extender is selected as ethylenediamine; The reaction time after adding the chain extender is 2-4 hours.

10. A fluorinated organosilicon-modified waterborne polyurethane coating, characterized in that, The fluorinated organosilicon-modified waterborne polyurethane coating is prepared by the preparation method according to any one of claims 1-9.

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