Intrinsic uvioresistant fluorine-containing waterborne polyurethane acrylate coating and preparation method thereof
By chemically bonding UV-resistant groups to the polyurethane acrylate backbone, an intrinsic UV-resistant network is constructed, solving the coating aging problem in high-altitude areas and improving weather resistance and environmental friendliness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-29
- Publication Date
- 2026-04-10
AI Technical Summary
Existing coatings are prone to aging and decreased adhesion under the conditions of high UV radiation intensity, large temperature difference, and wind and sand erosion in high-altitude areas. Physically blended UV-resistant additives have poor migration properties and cannot provide long-term protection.
An intrinsic UV-resistant network is constructed by chemically bonding UV-resistant groups to the polyurethane acrylate backbone. Combined with fluorinated acrylates, the coating's weather resistance is improved, and a waterborne polyurethane system is used to reduce VOC emissions.
It achieves long-lasting UV protection in high-altitude areas, improves the weather resistance and flexibility of the coating, reduces organic solvent emissions, and meets environmental protection requirements.
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Figure CN121825359A_ABST
Abstract
Description
Technical Field
[0001] The embodiments disclosed herein belong to the field of waterborne polyurethane preparation technology, specifically relating to an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating and its preparation method. Background Technology
[0002] In high-altitude areas (such as the Qinghai-Tibet Plateau and the canyons of western Sichuan), the intensity of ultraviolet radiation can reach 1.7–2.1 times that of plains (annual total radiation of 195 kcal / cm²). Combined with diurnal temperature differences exceeding 15°C, low oxygen levels, and wind and sand erosion, traditional steel structure coatings undergo accelerated photo-oxidation and aging, manifesting as chalking, loss of gloss (7–17% gloss loss rate in 6 months), and a sharp decline in adhesion, seriously threatening building safety. Existing protective technologies have significant limitations: while fluorocarbon topcoat systems possess some weather resistance, they rely on organic solvents (high VOC emissions), and physically mixed ultraviolet absorbers (such as benzophenones) are prone to migration and leaching, resulting in insufficient long-term effectiveness; glass flake anti-corrosion paints exhibit excellent sand erosion resistance, but lack flexibility and are prone to cracking under large temperature differences, and additive-type UV-resistant agents still show a gloss loss rate exceeding 15% under strong ultraviolet light; although nano-modified coatings can block the medium, the poor dispersion of nanoparticles leads to weakened interfacial bonding and peeling after ultraviolet aging. The core problem is that the UV protection function relies on physically blended modified additives, which cannot resist photodegradation at the molecular level, and the migration of small molecule absorbers further weakens the coating's long-lasting protective ability.
[0003] Recent studies indicate that chemically bonding UV-resistant groups (such as triazine groups) to the polymer backbone can solve the migration problem. However, this technology has not yet achieved breakthroughs in fluorinated waterborne polyurethane acrylate systems—while fluorinated segments improve weather resistance, they have poor compatibility with waterborne systems; polyurethane acrylates exhibit excellent flexibility, but their intrinsic UV resistance is insufficient. Therefore, there is an urgent need to develop a new coating material that combines intrinsic UV resistance (intramolecular bonding of UV-resistant groups), environmental adaptability (resistance to UV-temperature-oxidative corrosion coupling damage), and waterborne environmental friendliness, filling the technological gap in the field of long-term protection for high-altitude steel structures. Summary of the Invention
[0004] The embodiments disclosed herein aim to at least solve one of the technical problems existing in the prior art, and provide an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating and its preparation method.
[0005] The first aspect of this disclosure provides a method for preparing an intrinsically UV-resistant fluorinated waterborne polyurethane acrylate coating, the method comprising: S110. Isophorone diisocyanate, polytetrahydrofuran ether diol and dimethylolpropionic acid are stirred at the first temperature, and then a catalyst is added and stirred to react, so as to obtain a polyurethane prepolymer. S120. Add a chain extender to the polyurethane prepolymer, stir and react to complete the chain extension; S130. Cool the chain-extended reaction system to the second temperature, add the end-capping agent and continue stirring to complete the double bond end-capping. Then cool the system to the third temperature, add the neutralizing agent and continue stirring to complete the neutralization. S140. At a preset rotation speed, add low-temperature deionized water to the end-capped and neutralized reaction system, and emulsify the polyurethane under high-speed stirring to complete the conversion from oil phase to water phase and obtain polyurethane emulsion. S150. Add acrylate, fluorinated acrylate and acrylate UV absorber to the polyurethane emulsion. Stir at the fourth temperature and then add azobisisobutyramidine hydrochloride dissolved in water dropwise. The UV absorber is grafted onto the polyurethane main chain together with the fluorinated acrylate through the double bond sites provided by the end-capping agent. After the reaction is kept at a temperature, an intrinsic UV-resistant network is formed to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. S160. The intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion is coated into a mold and dried to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film. Optionally, the amount of isophorone diisocyanate added is 20-25% by weight of total solids; The amount of polytetrahydrofuran ether diol added is 35-40%; The amount of dimethylolpropionic acid added is 3-5%; The amount of the chain extender added is 3-5%; The amount of the capping agent added is 2-2.5%; The amount of the neutralizing agent added is 3-4%; The amount of acrylate added is 18-23%; The amount of the fluorinated acrylate added is 5-10%; The amount of the acrylate-based ultraviolet absorber added is 0.5-3.0%; The amount of azobisisobutyramidine hydrochloride added is 1.4-1.7% of the total mass of the acrylate, fluorinated acrylate, and acrylate UV absorber. The total amount of deionized water added is 65-75% of the total mass of the emulsion.
[0006] Optionally, in step S110, the first temperature is 75-85°C, and the stirring time at the first temperature is 0.5-1h; The catalyst is added and the reaction is stirred for 2-3 hours. The catalyst used is dibutyltin dilaurate.
[0007] Optionally, in step S120, the stirring reaction time for adding the chain extender to the polyurethane prepolymer is 2-3 hours; The chain extender is 1,4-butanediol.
[0008] Optionally, in step S130, the second temperature is 60-65°C, and the reaction time with continuous stirring after adding the capping agent is 0.5-1.5 h; The third temperature is 35-45℃, and the reaction time after adding the neutralizing agent is 20-40 minutes. The capping agent is hydroxyethyl methacrylate, and the neutralizing agent is triethylamine.
[0009] Optionally, in step S140, the preset rotational speed is 1500-2500 r / min.
[0010] Optionally, in step S150, the fourth temperature is 70-75°C, and the stirring time is 20-40 min; The time for adding azobisisobutyramidine hydrochloride dissolved in water was controlled at 2-3 hours, and the reaction time after addition was kept at a constant temperature for 3-4 hours.
[0011] Optionally, in step S150, the acrylate is at least two of methyl methacrylate, butyl acrylate, ethyl acrylate, glycidyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate. The fluorinated acrylate is one of perfluorohexyl ethyl acrylate, perfluorohexyl ethyl methacrylate, and perfluorooctyl ethyl acrylate; The acrylate-based ultraviolet absorber is 2-(4-benzoyl-3-hydroxyphenoxy)ethyl 2-acrylate.
[0012] Optionally, in step S160, the drying process includes: Air dry at room temperature for 4-5 days, then dry in a constant temperature drying oven at 60℃ for 20-25 hours.
[0013] This disclosure discloses an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating, which is prepared using the preparation method described in any of the above embodiments. This disclosure discloses an intrinsically UV-resistant fluorinated waterborne polyurethane acrylate coating and its preparation method. The preparation method includes: stirring isophorone diisocyanate, polytetrahydrofuran ether diol, and dimethylolpropionic acid at a first temperature, followed by adding a catalyst and stirring to obtain a polyurethane prepolymer; adding a chain extender to the polyurethane prepolymer and stirring to complete chain extension; cooling the chain-extended reaction system to a second temperature, adding a capping agent and stirring continuously to complete double bond capping, then cooling the system to a third temperature, adding a neutralizing agent and stirring continuously to complete neutralization; and rotating the capping and neutralization reactions at a preset speed. Low-temperature deionized water is added to the system, and the polyurethane is dispersed by the shear force of the high-speed rotation of the stirrer, completing the conversion from oil phase to water phase to obtain a polyurethane emulsion. Acrylate, fluorinated acrylate and acrylate-based ultraviolet absorber are added to the polyurethane emulsion. After stirring at a fourth temperature, azobisisobutyramidine hydrochloride dissolved in water is slowly added dropwise. After the dropwise addition is completed, the reaction is kept at a constant temperature to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. The intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion is coated into a mold and dried to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film. This disclosure constructs an intrinsic UV-resistant network structure by covalently bonding UV-absorbing groups to the polyurethane acrylate backbone, effectively avoiding the performance failure problems caused by the migration and seepage of traditional physically blended UV-resistant additives during long-term service, and significantly improving the UV protection durability of the coating. By introducing fluorinated acrylate monomers, the surface hydrophobicity and weather resistance of the coating are improved, enabling the material to better resist the coupled erosion of multiple environmental factors such as strong ultraviolet radiation, temperature differences, and wind and sand erosion in high-altitude areas. The prepared coating is based on a waterborne polyurethane system and does not rely on organic solvent systems, which significantly reduces volatile organic compound (VOC) emissions, helps to achieve green environmental protection goals, and meets the technical needs of ecological environmental protection in high-altitude areas. Attached Figure Description
[0014] Figure 1 This is a flowchart illustrating the preparation method of an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating according to an embodiment of this disclosure; Figure 2 The infrared spectra of embodiments 1-5 of the present invention are shown below; Figure 3 These are the emulsion particle size distribution diagrams for Examples 1-5 of the present invention; Figure 3 (a) is a particle size distribution diagram of the emulsion in Example 1; Figure 3 (b) is a particle size distribution diagram of the emulsion in Example 2; Figure 3 (c) is a particle size distribution diagram of the emulsion in Example 3; Figure 3 (d) is a particle size distribution diagram of the emulsion in Example 4; Figure 3 (e) is a particle size distribution diagram of the emulsion in Example 5; Figure 4These are ultraviolet transmittance diagrams for Examples 1-5 of the present invention; Figure 4 (a) is the ultraviolet transmittance diagram of Example 1; Figure 4 (b) is the UV transmittance diagram for Example 2; Figure 4 (c) is the UV transmittance diagram of Example 3; Figure 4 (d) is the UV transmittance diagram of Example 4; Figure 4 (e) is the UV transmittance diagram of Example 5. Detailed Implementation
[0015] 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 for explaining this disclosure and are not intended to limit the disclosure. The described embodiments are some, but not all, of the embodiments of this disclosure. Based on the described embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this disclosure.
[0016] like Figure 1 As shown, one aspect of this disclosure provides a method S100 for preparing an intrinsically UV-resistant fluorinated waterborne polyurethane acrylate coating, specifically including the following steps S110~S160: S110, Isophorone diisocyanate (IPDI), polytetrahydrofuran ether diol (PTMG 1000-2000) and dimethylolpropionic acid (DMPA) are stirred at a first temperature, and then a catalyst is added and stirred to react, to obtain a polyurethane prepolymer.
[0017] In step S110, the first temperature is 75-85℃, for example, preferably 75℃, 80℃, 85℃, etc., and the stirring time at the first temperature is 0.5-1h, for example, preferably 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, etc.
[0018] In step S110, the catalyst is added and the reaction is stirred for 2-3 hours, preferably 2 hours, 2.5 hours, or 3 hours.
[0019] In step S110, the catalyst used is dibutyltin dilaurate (DBTDL), which has high catalytic efficiency and high selectivity. It can enable the reaction to proceed rapidly at a relatively low temperature (e.g., 75-85℃), and can also significantly reduce the activation energy of the reaction between isophorone diisocyanate (IPDI) and polytetrahydrofuran ether diol (PTMG) and other polyols, thereby accelerating the reaction rate and enabling the prepolymerization reaction to be completed within 2-3 hours, thus shortening the production cycle.
[0020] In step S110, the amount of isophorone diisocyanate added is 20-25%, for example, preferably 20%, 22%, 24%, 25%, etc.
[0021] In step S110, the amount of polytetrahydrofuran ether diol added is 35-40%, for example, preferably 35%, 36%, 38%, 39%, etc.
[0022] In step S110, the amount of dimethylolpropionic acid added is 3-5%, for example, preferably 3%, 4%, 5%, etc.
[0023] S120. Add chain extender to polyurethane prepolymer, stir to react, and complete chain extension.
[0024] In step S120, the chain extender is added to the polyurethane prepolymer and the stirring reaction time is 2-3 hours, for example, preferably 2 hours, 2.5 hours, 3 hours, etc.
[0025] In step S120, the amount of chain extender added is 3-5%, for example, preferably 3%, 4%, 5%, etc. The chain extender is preferably 1,4-butanediol (BDO), whose hydroxyl groups can react quickly and fully with isocyanate groups, ensuring that the chain extension reaction proceeds efficiently, shortening the reaction time and improving production efficiency.
[0026] S130. Cool the chain-extended reaction system to the second temperature, add the end-capping agent and continue stirring to complete the double bond end-capping. Then cool the system to the third temperature, add the neutralizing agent and continue stirring to complete the neutralization.
[0027] In step S130, the second temperature is 60-65℃, for example, preferably 60℃, 62℃, 63℃, 65℃, etc., and the reaction time after adding the capping agent is 0.5-1.5h, for example, preferably 0.5, 1h, 1.5h, etc.; the third temperature is 35-45℃, for example, preferably 35℃, 40℃, 45℃, etc., and the reaction time after adding the neutralizing agent is 20-40min, for example, preferably 20min, 25min, 30min, 35min, 40min, etc.
[0028] In step S130, the amount of end-capping agent added is 2-2.5%, preferably 2%, 2.3%, or 2.5%. The end-capping agent is preferably hydroxyethyl methacrylate (HEMA), which has a hydroxyl group at one end, allowing it to react with the polyurethane prepolymer and attach itself to the polyurethane molecular chain. Simultaneously, the other end of the end-capping agent is a double bond, providing reaction sites for the subsequent graft polymerization of fluorinated acrylates and acrylate-based UV absorbers. This allows fluorinated functional monomers and UV-resistant groups to be covalently introduced into the polymer backbone, constructing an intrinsic UV-resistant-hydrophobic bifunctional network. Furthermore, by reacting with the polyurethane prepolymer, further chain growth is restricted, stabilizing the polymer molecular weight and giving the polymer a regular structure, ensuring the uniformity of product performance. Simultaneously, the introduced double bond participates in cross-linking in subsequent reactions, constructing a specific molecular network structure and regulating the physicochemical properties of the polymer.
[0029] In step S130, the amount of neutralizing agent added is 3-4%, for example, preferably 3%, 3.5%, 4%, etc. The neutralizing agent is preferably triethylamine (TEA), which, as an organic base, reacts with acidic groups in the system (such as the carboxyl group in dimethylolpropionic acid) to form a salt. The product after salt formation is hydrophilic, which can make the polymer uniformly dispersed in water, thus preparing an aqueous system and giving the coating water-based and environmentally friendly properties.
[0030] S140. Increase the speed of the stirrer to the preset speed, and slowly add low-temperature deionized water to the end-sealing and neutralization reaction system of step S130. Use the shear force of the high-speed rotation of the stirrer to emulsify the polyurethane, complete the conversion from oil phase to water phase, and obtain polyurethane emulsion.
[0031] In step S140, the preset rotational speed is 1500-2500 r / min, for example, preferably 1500 r / min, 2000 r / min, or 2500 r / min.
[0032] In step S140, the amount of deionized water added is 50-60% of the total mass of the emulsion. It should be understood that the amount of deionized water added here refers to the low-temperature deionized water added in step S140, and the total mass of the emulsion refers to the total mass of all added reagents and deionized water.
[0033] S150. Acrylic ester, fluorinated acrylate and acrylate-based ultraviolet absorber are added to a polyurethane emulsion. After stirring at the fourth temperature, azobisisobutyramidine hydrochloride (AIBA) dissolved in water is slowly added dropwise. The ultraviolet absorber is grafted onto the polyurethane backbone together with the fluorinated acrylate through the double bond sites provided by the end-capping agent. After the dropwise addition and heat preservation reaction are completed, an intrinsic anti-ultraviolet network is formed, and an intrinsic anti-ultraviolet fluorinated waterborne polyurethane acrylate (FWPUA) emulsion is obtained.
[0034] In step S150, the fourth temperature is 70-75℃, preferably 70℃, 72℃, or 75℃, and the stirring time is 20-40 min, preferably 20 min, 30 min, or 40 min. Furthermore, the time for adding azobisisobutyramidine hydrochloride dissolved in water is controlled at 2-3 hours, for example, 2 hours, 2.5 hours, or 3 hours, and the reaction time after the addition is 3-4 hours, for example, 3 hours, 3.5 hours, or 4 hours.
[0035] In step S150, the amount of acrylate added is 18-23%, preferably 18%, 19%, 20%, 21%, 22%, 23%, etc. Furthermore, the acrylate can be a combination of two or more of methyl methacrylate (MMA), butyl acrylate (BA), ethyl acrylate (EA), glycidyl methacrylate (GMA), isooctyl acrylate (2-EHA), and hydroxyethyl acrylate (HEA). For example, methyl methacrylate (MMA) and butyl acrylate (BA) are preferred.
[0036] In step S150, the amount of fluorinated acrylate added is 5-10%, preferably 5%, 6%, 7%, 8%, 9%, 10%, etc. Furthermore, the fluorinated acrylate can be one of perfluoroalkyl ethyl acrylates such as perfluorohexyl ethyl acrylate (TEAc-6), perfluorohexyl ethyl methacrylate (TEMAc-6), and perfluorooctyl ethyl acrylate (TEAc-8).
[0037] In step S150, the amount of acrylate-based ultraviolet absorber added is 0.5-3.0%, preferably 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, etc. The acrylate-based ultraviolet absorber is one of 2-(4-benzoyl-3-hydroxyphenoxy)ethyl 2-acrylate (UV-416), 2-cyano-3,3-diphenyl-2-acrylate-2-ethylhexyl ester (UV-3039), and 2-cyano-3,3-diphenyl-2-acrylate-ethyl ester (UV-3035).
[0038] In step S150, the amount of azobisisobutyramidine hydrochloride added is 1.4-1.7% of the total mass of the acrylate, fluorinated acrylate and acrylate UV absorber, for example, preferably about 1.5%.
[0039] It should be understood that the total amount of deionized water added includes the amount of deionized water added in step S140 and the amount of deionized water added in step S150. Thus, when the total amount of deionized water added is 65-75% of the total mass of the emulsion and the amount of deionized water added in step S140 is 50-60% of the total mass of the emulsion, the amount of deionized water added in step S150 should be 5-25% of the total mass of the emulsion. That is to say, 2-5% of azobisisobutyramidine hydrochloride (AIBA) is dissolved in 5-25% of the total mass of the emulsion in deionized water.
[0040] S160. The intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion is coated into a mold and dried to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film. In step S160, the drying process includes: air drying at room temperature for 4-5 days, and drying in a constant temperature drying oven at 60℃ for 20-25 hours to complete the drying.
[0041] This disclosure addresses the core issue of accelerated UV aging in steel structure building coatings under strong UV conditions in high-altitude environments. Through molecular structural innovation, it solves the shortcomings of existing technologies that rely on physically blended UV-resistant additives, such as migration and seepage, insufficient long-term effectiveness, and poor environmental adaptability. In the embodiments of this disclosure, fluorinated segments are chemically bonded to the polyurethane acrylate backbone with UV-absorbing groups to construct an intrinsic UV-resistant network. This design achieves three breakthroughs: (1) the UV-resistant groups are covalently embedded in the polymer backbone, completely avoiding the migration problem of small molecule additives and ensuring long-term protection; (2) the fluorinated segments enhance the hydrophobicity and weather resistance of the coating, synergistically resisting UV-temperature-wind-sand coupling erosion; (3) the water-based system reduces VOC pollution, meeting the needs of high-altitude ecological protection.
[0042] In another aspect of this disclosure, an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating is proposed. This intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating is prepared using the preparation method described above. For details of the process, please refer to the above description, which will not be repeated here.
[0043] The preparation method of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating will be further explained below with reference to specific embodiments: Example 1 The preparation method of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating in this example includes the following steps: (1) Fill a water bath with water and heat it to 80 °C. Weigh 6.32 g of IPDI, 10 g of PTMG-2000 and 1.13 g of DMPA and place them in a three-necked flask. Adjust the speed of the stirrer to 200 r / min and stir for 0.5 h. Then add 2 drops of DBTDL and continue stirring for 2 h to obtain polyurethane prepolymer with isocyanate end capping. (2) Add 0.88 g of BDO to a three-necked flask and stir for 2 h to complete the chain extension; (3) Cool the reaction system to 65°C, weigh 0.6 g HEMA and add it to a three-necked flask. Continue the reaction for 1 h to complete the double bond end sealing. Then cool the system to 40°C, add 0.99 g TEA, and continue stirring for 0.5 h to complete the neutralization. (4) Weigh 50g of low-temperature deionized water, increase the speed of the stirrer to 2000 r / min, slowly add the weighed low-temperature deionized water while increasing the speed, and continue stirring for 15 min. After stirring, let it stand to obtain a semi-transparent waterborne polyurethane emulsion. (5) Heat the reaction system to 75°C, weigh 3.37 g BA, 2.75 g MMA, 2.28 g TEAc-6 and 0.14 g UV-416 into the reaction system, stir the reaction for 0.5 h and then slowly add 0.13 g AIBA (dissolved in 10 g deionized water) dropwise. The dropwise addition is completed within 2 h. Then keep the reaction at the temperature for 4 h to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. (6) Take 20 mL of the above emulsion and coat it in a 10×10 mm polytetrafluoroethylene mold. After air drying at room temperature for 4-5 days, dry it further in a constant temperature drying oven. After drying at 60℃ for 24 h, the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film is obtained.
[0044] Example 2 The preparation method of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating in this example includes the following steps: (1) Fill a water bath with water and heat it to 80 °C. Weigh 6.32 g IPDI, 10 g PTMG-2000 and 1.13 g DMPA and place them in a three-necked flask. Adjust the stirring speed to 200 r / min and stir for 0.5 h. Then add 2 drops of DBTDL and continue stirring for 2 h to obtain polyurethane prepolymer with isocyanate end capping. (2) Add 0.88 g of BDO to a three-necked flask and stir for 2 h to complete the chain extension; (3) Cool the reaction system to 65°C, weigh 0.6 g HEMA and add it to a three-necked flask. Continue the reaction for 1 h to complete the double bond end sealing. Then cool the system to 40°C, add 0.99 g TEA, and continue stirring for 0.5 h to complete the neutralization. (4) Weigh 50g of low-temperature deionized water, increase the speed of the stirrer to 2000 r / min, slowly add the weighed low-temperature deionized water while increasing the speed, and continue stirring for 15 min. After stirring, let it stand to obtain a semi-transparent waterborne polyurethane emulsion. (5) Heat the reaction system to 75°C, weigh 3.29 g BA, 2.69 g MMA, 2.28 g TEAc-6 and 0.28 g UV-416 into the reaction system, stir the reaction for 0.5 h and then slowly add 0.13 g AIBA (dissolved in 10 g deionized water) dropwise. The dropwise addition is completed within 2 h. Then keep the reaction at the temperature for 4 h to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. (6) Take 20 mL of the above emulsion and coat it in a 10×10 mm polytetrafluoroethylene mold. After air drying at room temperature for 4-5 days, dry it further in a constant temperature drying oven. After drying at 60℃ for 24 h, the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film is obtained.
[0045] Example 3 The preparation method of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating in this example includes the following steps: (1) Fill a water bath with water and heat it to 80 °C. Weigh 6.32 g IPDI, 10 g PTMG-2000 and 1.13 g DMPA and place them in a three-necked flask. Adjust the stirring speed to 200 r / min and stir for 0.5 h. Then add 2 drops of DBTDL and continue stirring for 2 h to obtain polyurethane prepolymer with isocyanate end capping. (2) Add 0.88 g of BDO to a three-necked flask and stir for 2 h to complete the chain extension; (3) Cool the reaction system to 65°C, weigh 0.6 g HEMA and add it to a three-necked flask. Continue the reaction for 1 h to complete the double bond end sealing. Then cool the system to 40°C, add 0.99 g TEA, and continue stirring for 0.5 h to complete the neutralization. (4) Weigh 50 g of low-temperature deionized water, increase the speed of the stirrer to 2000 r / min, slowly add the weighed low-temperature deionized water while increasing the speed, and continue stirring for 15 min. After stirring, let it stand to obtain a semi-transparent waterborne polyurethane emulsion. (5) Heat the reaction system to 75℃, weigh 3.21 g BA, 2.62 g MMA, 2.28 g TEAc-6 and 0.43 g UV-416 into the reaction system, stir the reaction for 0.5 h and then slowly add 0.13 g AIBA (dissolved in 10 g deionized water) dropwise. The dropwise addition is completed within 2 h. Then keep the reaction at the temperature for 4 h to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. (6) Take 20 mL of the above emulsion and coat it in a 10×10 mm polytetrafluoroethylene mold. After air drying at room temperature for 4-5 days, dry it further in a constant temperature drying oven. After drying at 60℃ for 24 h, the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film is obtained.
[0046] Example 4 The preparation method of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating in this example includes the following steps: (1) Fill a water bath with water and heat it to 80 °C. Weigh 6.32 g IPDI, 10 g PTMG-2000 and 1.13 g DMPA and place them in a three-necked flask. Adjust the stirring speed to 200 r / min and stir for 0.5 h. Then add 2 drops of DBTDL and continue stirring for 2 h to obtain polyurethane prepolymer with isocyanate end capping. (2) Add 0.88 g of BDO to a three-necked flask and stir for 2 h to complete the chain extension; (3) Cool the reaction system to 65°C, weigh 0.6 g HEMA and add it to a three-necked flask. Continue the reaction for 1 h to complete the double bond end sealing. Then cool the system to 40°C, add 0.99 g TEA, and continue stirring for 0.5 h to complete the neutralization. (4) Weigh 50 g of low-temperature deionized water, increase the speed of the stirrer to 2000 r / min, slowly add the weighed low-temperature deionized water while increasing the speed, and continue stirring for 15 min. After stirring, let it stand to obtain a semi-transparent waterborne polyurethane emulsion. (5) Heat the reaction system to 75°C, weigh 3.13 g BA, 2.56 g MMA, 2.28 g TEAc-6 and 0.57 g UV-416 into the reaction system, stir the reaction for 0.5 h and then slowly add 0.13 g AIBA (dissolved in 10 g deionized water) dropwise. The dropwise addition is completed within 2 h. Then keep the reaction at the temperature for 4 h to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. (6) Take 20 mL of the above emulsion and coat it in a 10×10 mm polytetrafluoroethylene mold. After air drying at room temperature for 4-5 days, dry it further in a constant temperature drying oven. After drying at 60℃ for 24 h, the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film is obtained.
[0047] Example 5 The preparation method of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating in this example includes the following steps: (1) Fill a water bath with water and heat it to 80 °C. Weigh 6.32 g IPDI, 10 g PTMG-2000 and 1.13 g DMPA and place them in a three-necked flask. Adjust the stirring speed to 200 r / min and stir for 0.5 h. Then add 2 drops of DBTDL and continue stirring for 2 h to obtain polyurethane prepolymer with isocyanate end capping. (2) Add 0.88 g of BDO to a three-necked flask and stir for 2 h to complete the chain extension; (3) Cool the reaction system to 65°C, weigh 0.6 g HEMA and add it to a three-necked flask. Continue the reaction for 1 h to complete the double bond end sealing. Then cool the system to 40°C, add 0.99 g TEA, and continue stirring for 0.5 h to complete the neutralization. (4) Weigh 50g of low-temperature deionized water, increase the speed of the stirrer to 2000 r / min, slowly add the weighed low-temperature deionized water while increasing the speed, and continue stirring for 15 min. After stirring, let it stand to obtain a semi-transparent waterborne polyurethane emulsion. (5) Heat the reaction system to 75°C, weigh 3.05 g BA, 2.50 g MMA, 2.28 g TEAc-6 and 0.71 g UV-416 into the reaction system, stir the reaction for 0.5 h and then slowly add 0.13 g AIBA (dissolved in 10 g deionized water) dropwise. The dropwise addition is completed within 2 h. Then keep the reaction at the temperature for 4 h to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. (6) Take 20 mL of the above emulsion and coat it in a 10×10 mm polytetrafluoroethylene mold. After air drying at room temperature for 4-5 days, dry it further in a constant temperature drying oven. After drying at 60℃ for 24 h, the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film is obtained.
[0048] The infrared spectra of Examples 1-5 above are as follows: Figure 2 As shown, the FT-IR spectra of intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coatings with different UV-416 contents are displayed. Figure 2 Analysis shows that 1640cm -1At this point, the peak corresponds to the skeletal vibration of the benzene ring; while the curve at 720 cm⁻¹... -1 The presence of the out-of-plane bending vibration peak corresponding to the trisubstituted benzene indicates that UV-416 has been introduced into the fluorinated waterborne polyurethane acrylate system. (Curve 1700cm) -1 The absorption peak at 1000 cm⁻¹ is the stretching vibration absorption peak of C=O. -1 The corresponding point is the symmetrical stretching vibration of the COC structure, curve 1210cm. -1 The corresponding point corresponds to the asymmetric stretching vibration of the COC structure, which is the most significant characteristic absorption of polyurethane.
[0049] The emulsion particle size distribution diagrams of Examples 1-5 above are shown below. Figure 3 As shown, with the increase of UV-416 content, the particle size of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion first gradually decreased and then increased. The emulsion particle sizes of Examples 1-5 were 58.8 nm, 56.6 nm, 52.5 nm, 53.2 nm, and 55.1 nm, respectively. Example 3 showed the smallest average particle size and the best dispersion. This indicates that using UV-416 to modify fluorinated waterborne polyurethane acrylate can reduce its agglomeration effect to a certain extent. However, when the UV-416 content continued to increase to Example 5, the excessive UV-416 content led to self-polymerization, reducing the dispersion and thus increasing the average particle size of the intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion.
[0050] The ultraviolet transmittance of Examples 1-5 above is as follows: Figure 4 As shown, the addition of acrylate-based UV absorbers, by introducing double-bonded groups into the hydrophobic polyurethane backbone to embed hydrophilic segments, strongly absorbs UV light, thereby reducing the damaging effects of UV light on the substrate. This is manifested in the figure as a significant redshift in wavelength when UV light is completely blocked. The coating achieves complete shielding in the main UV wavelength range of 200-375 nm. Comparing the visible light transmittance (400-800 nm) of each embodiment before and after strong UV irradiation, it can be seen that the visible light transmittance of Examples 1-5 is well maintained, with Example 3 showing the best performance. This indicates excellent UV shielding performance without affecting the normal transmission of visible light.
[0051] This disclosure presents an intrinsically UV-resistant fluorinated waterborne polyurethane acrylate coating and its preparation method, which has the following advantages over the prior art: 1. By covalently bonding ultraviolet-absorbing groups to the polyurethane acrylate backbone, an intrinsic UV-resistant network structure is constructed, which effectively avoids the performance failure problem caused by the easy migration and exudation of traditional physically blended UV-resistant additives during long-term service, and significantly improves the UV protection durability of the coating.
[0052] 2. By introducing fluorinated acrylate monomers, the surface hydrophobicity and weather resistance of the coating are improved, enabling the material to better resist the coupled erosion of multiple environmental factors such as strong ultraviolet radiation, temperature difference changes and wind and sand erosion in high-altitude areas.
[0053] 3. The prepared coating is based on a water-based polyurethane system and does not rely on organic solvent systems, which significantly reduces the emission of volatile organic compounds (VOCs), helps to achieve green and environmentally friendly goals, and meets the technical needs of plateau ecological environment protection.
[0054] 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 an intrinsically UV-resistant fluorinated waterborne polyurethane acrylate coating, characterized in that, The preparation method includes: S110. Isophorone diisocyanate, polytetrahydrofuran ether diol and dimethylolpropionic acid are stirred at the first temperature, and then a catalyst is added and stirred to react, so as to obtain a polyurethane prepolymer. S120. Add a chain extender to the polyurethane prepolymer, stir and react to complete the chain extension; S130. Cool the chain-extended reaction system to the second temperature, add the end-capping agent and continue stirring to complete the double bond end-capping. Then cool the system to the third temperature, add the neutralizing agent and continue stirring to complete the neutralization. S140. At a preset rotation speed, add low-temperature deionized water to the end-capped and neutralized reaction system, and disperse the polyurethane under high-speed stirring to complete the conversion from oil phase to water phase and obtain polyurethane emulsion. S150. Add acrylate, fluorinated acrylate and acrylate UV absorber to the polyurethane emulsion. Stir at the fourth temperature and then add azobisisobutyramidine hydrochloride dissolved in water dropwise. The UV absorber is grafted onto the polyurethane main chain together with the fluorinated acrylate through the double bond sites provided by the end-capping agent. After the reaction is kept at a temperature, an intrinsic UV-resistant network is formed to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion. S160. The intrinsic UV-resistant fluorinated waterborne polyurethane acrylate emulsion is coated into a mold and dried to obtain an intrinsic UV-resistant fluorinated waterborne polyurethane acrylate film.
2. The preparation method according to claim 1, characterized in that, The amount of isophorone diisocyanate added is 20-25% by weight of total solids; The amount of polytetrahydrofuran ether diol added is 35-40%; The amount of dimethylolpropionic acid added is 3-5%; The amount of the chain extender added is 3-5%; The amount of the capping agent added is 2-2.5%; The amount of the neutralizing agent added is 3-4%; The amount of acrylate added is 18-23%; The amount of the fluorinated acrylate added is 5-10%; The amount of the acrylate-based ultraviolet absorber added is 0.5-3.0%; The amount of azobisisobutyramidine hydrochloride added is 1.4-1.7% of the total mass of the acrylate, fluorinated acrylate, and acrylate UV absorber. The total amount of deionized water added is 65-75% of the total mass of the emulsion.
3. The preparation method according to claim 1, characterized in that, In step S110, the first temperature is 75-85℃, and the stirring time at the first temperature is 0.5-1h; The catalyst is added and the reaction is stirred for 2-3 hours. The catalyst used is dibutyltin dilaurate.
4. The preparation method according to claim 1, characterized in that, In step S120, the stirring reaction time for adding the chain extender to the polyurethane prepolymer is 2-3 hours. The chain extender is 1,4-butanediol.
5. The preparation method according to claim 1, characterized in that, In step S130, the second temperature is 60-65℃, and the reaction time with continuous stirring after adding the capping agent is 0.5-1.5h. The third temperature is 35-45℃, and the reaction time after adding the neutralizing agent is 20-40 minutes. The capping agent is hydroxyethyl methacrylate, and the neutralizing agent is triethylamine.
6. The preparation method according to claim 1, characterized in that, In step S140, the preset rotational speed is 1500-2500 r / min.
7. The preparation method according to claim 1, characterized in that, In step S150, the fourth temperature is 70-75℃, and the stirring time is 20-40 min; The time for adding azobisisobutyramidine hydrochloride dissolved in water was controlled at 2-3 hours, and the reaction time after addition was kept at a constant temperature for 3-4 hours.
8. The preparation method according to claim 1, characterized in that, In step S150, the acrylate is at least two of the following: methyl methacrylate, butyl acrylate, ethyl acrylate, glycidyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate. The fluorinated acrylate is one of perfluorohexyl ethyl acrylate, perfluorohexyl ethyl methacrylate, and perfluorooctyl ethyl acrylate; The acrylate-based ultraviolet absorber is 2-(4-benzoyl-3-hydroxyphenoxy)ethyl 2-acrylate.
9. The preparation method according to claim 1, characterized in that, In step S160, the drying process includes: Air dry at room temperature for 4-5 days, then dry in a constant temperature drying oven at 60℃ for 20-25 hours.
10. An intrinsically UV-resistant fluorinated waterborne polyurethane acrylate coating, characterized in that, The intrinsic UV-resistant fluorinated waterborne polyurethane acrylate coating is prepared using the preparation method described in any one of claims 1-9.