Preparation method of uv functional fluorine-containing coating material for high-transmittance wear-resistant pet film

Abstract

The application discloses a kind of preparation methods of UV functional fluorine-containing coating materials for high-transmittance wear-resistant PET film, and relates to the technical field of polymer functional coating materials.The UV curing coating system is prepared by introducing low surface energy fluorine-containing monomer into fluorine-containing polyurethane acrylate as main body resin, through compounding photoinitiator, combining active diluent and functional additives.Dense crosslinking network structure is formed on the surface of PET substrate after coating and ultraviolet curing.The obtained coating has high light transmittance, high hardness, excellent wear resistance and good hydrophobic and oleophobic properties.The application has simple process, fast curing speed, and is suitable for optical film, display protection film and other fields.

Description

Technical Field

[0001] This invention relates to the field of polymer functional coating materials technology, and in particular to a method for preparing a UV-functional fluorinated coating material for high-transparency and wear-resistant PET film. Background Technology

[0002] Polyethylene terephthalate (PET) film is widely used in display protective films, optical antireflective films, flexible electronic devices, and new energy devices due to its excellent mechanical properties, dimensional stability, and good optical transparency. However, PET material itself has defects such as low surface hardness, poor abrasion resistance, easy scratching, and high surface energy that makes it prone to contamination, which limits its further application in high-end optical and functional film fields.

[0003] To improve the surface properties of PET films, existing technologies typically employ surface coating modification methods. Among these, UV-cured coating technology has become one of the mainstream technologies due to its advantages such as fast curing speed, low energy consumption, and environmental friendliness. By initiating free radical polymerization of acrylate monomers or oligomers using ultraviolet light, a dense cross-linked protective layer can be formed on the PET surface, thereby improving hardness and abrasion resistance. However, traditional UV coating systems still have the following problems: (1) Although cross-linked structures can improve hardness, they can also lead to increased coating brittleness. (2) The coating has a high surface energy, but its anti-fouling and anti-fingerprint properties are insufficient; (3) In high-transmittance application scenarios, problems such as increased haze or decreased light transmittance are likely to occur; (4) Some systems have defects such as insufficient weather resistance and easy yellowing.

[0004] To address the aforementioned issues, the introduction of fluorinated materials has become an important direction for modification. Fluoropolymers, due to their high C–F bond energy and low polarity, possess excellent chemical stability, low surface energy, and weather resistance, significantly improving the hydrophobicity, oleophobicity, and stain resistance of coatings. Related research indicates that fluorinated polymer coatings have significant application value in electronic materials and functional thin films, offering advantages such as heat resistance, oxidation resistance, and excellent interfacial stability.

[0005] In terms of patented technology, for example, CN103275570B discloses a fluoropolymer coating film and its preparation method, which improves the chemical resistance and surface properties of the material by forming a fluoropolymer coating on the surface of the substrate. However, this technology focuses more on corrosion resistance and chemical stability, and there are still shortcomings in the synergistic optimization of optical transparency and wear resistance.

[0006] For example, CN101663367B proposes a fluorinated copolymer coating system that can improve the surface properties of the base film. However, the system mainly relies on traditional solvent-based or thermosetting methods, which have problems such as low curing efficiency and complex processes, making it difficult to meet the needs of modern high-speed coating and green manufacturing.

[0007] In addition, in the field of PET functional films, such as CN208393968U, the functionality of PET films is improved through multi-layer structure design. However, this type of technology mainly relies on multi-layer composite structures to achieve performance improvement, which has problems such as complex processes, high costs and insufficient interface stability.

[0008] Meanwhile, CN101351521B relates to fluorinated coating films for photovoltaic modules, which focus on weather resistance and environmental stability, but the balance between high light transmittance and high wear resistance has not been fully resolved.

[0009] In summary, although existing technologies have made some progress in fluorinated coatings or UV curing systems, the following key technical bottlenecks still exist: 1. It is difficult to achieve both high light transmittance and high abrasion resistance simultaneously; 2. There is a contradiction between low surface energy and coating adhesion; 3. Fluorine-containing components are prone to phase separation, affecting coating uniformity and optical properties; 4. Some systems have insufficient curing efficiency and industrial adaptability.

[0010] Therefore, developing a fluorinated coating material and its preparation method that combines high light transmittance, high wear resistance, excellent hydrophobic and oleophobic properties with rapid UV curing characteristics is of great significance for improving the application performance of PET films in the optical and electronic fields. Summary of the Invention

[0011] Based on the problems raised in the background art, the present invention proposes a method for preparing a UV-functional fluorinated coating material for high-transparency and wear-resistant PET film.

[0012] The technical solution is as follows: A method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film includes the following steps: (1) Preparation of fluorinated polyurethane acrylate prepolymer According to the mass fractions, 40-80 parts of diisocyanate, 29-56 parts of polycarbonate diol, 2-6 parts of 2,3-dihydroxysuccinyl hydrazine (CAS: 292644-27-0), 0.2-0.6 parts of 2,7-dihydroxy-9-fluorenone (CAS: 42523-29-5), and 6-10 parts of fluorinated alcohol were added to a reaction vessel and reacted at 75-85°C for 1.5-2.5 h; then 8-12 parts of hydroxyethyl acrylate (HEA) were added for end-capping reaction for 0.5-1 h to obtain fluorinated polyurethane acrylate prepolymer; (2) Preparation of UV coating base material Add 40-55 parts of the above prepolymer to a reaction vessel, add 30-45 parts of reactive diluent at 40-55°C, and stir for 20-40 minutes to make the system uniform. (3) Introduction of functional components Add 4-8 parts of fluorine-containing active monomer and 4-7 parts of photoinitiator to the system obtained in step (2), and continue stirring for 15-25 minutes; (4) Additive regulation Add 0.3-0.8 parts of leveling agent and 0.2-0.6 parts of defoamer, disperse at 1000-2000 rpm for 10-20 min, and filter through a 1-5 μm filter membrane; (5) Coating and leveling The obtained coating is applied to the surface of PET film by wire bar or slit coating, with the wet film thickness controlled at 4-8 μm, and leveled at 50-70℃ for 1-3 min. (6) UV curing Irradiation with ultraviolet light at an intensity of 80–120 mW / cm² for 3–8 seconds resulted in the formation of a high-transmittance, wear-resistant, fluorine-containing coating with a thickness of 2–5 μm.

[0013] Further, the diisocyanate is one or both of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI), with a mass ratio of IPDI:HDI = 1:(0-1).

[0014] Furthermore, the polycarbonate diol has a molecular weight of 800–1500 g / mol and a hydroxyl value of 70–140 mg KOH / g.

[0015] Furthermore, the fluorinated alcohol is a perfluoroalkyl ethanol with a carbon chain length of C6 to C10.

[0016] Furthermore, the active diluent is a polyfunctional acrylate, which is composed of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:(0.6-1.2).

[0017] Furthermore, the fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 25-45 wt% and a molecular weight of 300-800.

[0018] Furthermore, the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO, with a mass ratio of 1:(1-2).

[0019] Furthermore, the leveling agent is selected from polydimethylsiloxane or polyether-modified polydimethylsiloxane.

[0020] Furthermore, the defoamer is selected from polydimethylsiloxane or poloxamer 188.

[0021] Furthermore, in step (6), the ultraviolet light wavelength is 250–420 nm, and the curing energy is 500–1200 mJ / cm².

[0022] Reaction Mechanism: Polycarbonate diol, diisocyanate, and fluorinated alcohol undergo stepwise polymerization to construct the polyurethane backbone. 2,3-Dihydroxysuccinyl hydrazine and 2,7-dihydroxy-9-fluorenone are covalently embedded in the backbone via hydroxyl groups. The hydrazine group provides intermolecular hydrogen bonding sites, and the rigid aromatic ring of the fluorenone has a regular chain segment arrangement, which synergistically improves the system's compatibility and crosslinking stability. The system is end-capped with acrylate to obtain photocurable activity. After compounding with reactive diluents, fluorinated reactive monomers, and photoinitiators, a dense crosslinked network is rapidly formed under ultraviolet irradiation. During the curing process, the fluorinated components migrate and accumulate in a directional manner, ultimately forming a high-transparency and wear-resistant functional coating on the surface of the PET substrate.

[0023] Compared with the prior art, the present invention has the following advantages: 1. Significantly improves the hydrophobic and oleophobic properties of the coating: By introducing fluorinated segments into the polyurethane acrylate system, the low surface energy fluorine groups spontaneously migrate and accumulate on the coating surface during UV curing, thereby significantly reducing the surface free energy and improving the hydrophobic properties.

[0024] 2. Achieving synergistic optimization of high light transmittance and low haze: By controlling the amount of fluorinated monomers added and the system compatibility, this invention effectively avoids the light scattering problem caused by microphase separation in traditional fluorinated systems, thereby ensuring that the coating has excellent optical performance.

[0025] 3. Improved coating hardness and wear resistance: Through the design of the polyurethane soft and hard segment structure and the UV curing crosslinking effect, the coating forms a good interfacial bond on the PET substrate surface. On the one hand, the polyurethane structure provides flexibility and interfacial adaptability; on the other hand, the crosslinked network formed by UV curing increases the interfacial mechanical interlocking effect.

[0026] 4. Enhanced weather resistance and chemical resistance of the coating: The high bond energy of the C–F bonds in the fluorine-containing structure gives the coating excellent heat resistance, UV resistance, and chemical corrosion resistance. At the same time, the dense cross-linked network reduces the penetration of moisture and corrosive media. Detailed Implementation

[0027] The features of the present invention are further illustrated below through embodiments, but the scope of protection of this patent is not limited to the embodiments.

[0028] Example 1 (1) Preparation of fluorinated polyurethane acrylate prepolymer Weigh out 40g of diisocyanate, 29g of polycarbonate diol, 2g of 2,3-dihydroxysuccinyl hydrazine (CAS: 292644-27-0), 0.2g of 2,7-dihydroxy-9-fluorenone (CAS: 42523-29-5), and 6g of fluorinated alcohol by weight and add them to a reaction vessel. React at 75°C for 1.5h. Then add 8g of hydroxyethyl acrylate (HEA) for end-capping reaction for 0.5h to obtain fluorinated polyurethane acrylate prepolymer. The diisocyanate is isophorone diisocyanate IPDI (mass ratio IPDI:HDI=1:0); the polycarbonate diol has a molecular weight of 800 g / mol and a hydroxyl value of 70 mg KOH / g; the fluorinated alcohol is perfluoroalkyl ethanol with a carbon chain length of C6.

[0029] (2) Preparation of UV coating base material Add 40g of the above prepolymer to the reaction vessel, add 30g of reactive diluent at 40°C, and stir for 20 minutes to make the system uniform. The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:0.6.

[0030] (3) Introduction of functional components Add 4g of fluorine-containing active monomer and 4g of photoinitiator to the system obtained in step (2), and continue stirring for 15 minutes; The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 25 wt% and a molecular weight of 300; the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO in a mass ratio of 1:1.

[0031] (4) Additive regulation Add 0.3g of leveling agent and 0.2g of defoamer, disperse at 1000rpm for 10min, and filter through a 1μm filter membrane; The leveling agent is selected from polydimethylsiloxane; the defoamer is selected from polydimethylsiloxane.

[0032] (5) Coating and leveling The obtained coating was applied to the surface of a PET film by wire bar coating, with the wet film thickness controlled at 4 μm, and leveled at 50°C for 1 min.

[0033] (6) UV curing Irradiation for 3 seconds under ultraviolet light intensity of 80mW / cm² and wavelength of 250nm, with a curing energy of 500mJ / cm², resulted in a high-transparency, wear-resistant fluorinated coating with a thickness of 2μm.

[0034] Example 2 (1) Preparation of fluorinated polyurethane acrylate prepolymer Weigh out the following ingredients by weight: 55g of diisocyanate, 38g of polycarbonate diol, 3.5g of 2,3-dihydroxysuccinyl hydrazine (CAS: 292644-27-0), 0.3g of 2,7-dihydroxy-9-fluorenone (CAS: 42523-29-5), and 7g of fluorinated alcohol. Add them to a reaction vessel and react at 78°C for 1.8h. Then add 9g of hydroxyethyl acrylate (HEA) for end-capping reaction for 0.7h to obtain fluorinated polyurethane acrylate prepolymer. The diisocyanate is a combination of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) (mass ratio IPDI:HDI = 1:0.3); the polycarbonate diol has a molecular weight of 1000 g / mol and a hydroxyl value of 90 mg KOH / g; the fluorinated alcohol is perfluoroalkyl ethanol with a carbon chain length of C7.

[0035] (2) Preparation of UV coating base material Add 46g of the above prepolymer to the reaction vessel, add 36g of reactive diluent at 45°C, and stir for 28 minutes to make the system homogeneous. The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:0.8.

[0036] (3) Introduction of functional components Add 5.5g of fluorine-containing active monomer and 5g of photoinitiator to the system obtained in step (2), and continue stirring for 18min; The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 32 wt% and a molecular weight of 450; the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO in a mass ratio of 1:1.3.

[0037] (4) Additive regulation Add 0.5g of leveling agent and 0.3g of defoamer, disperse at 1400rpm for 14min, and filter through a 2.5μm filter membrane; The leveling agent is selected from polyether-modified polydimethylsiloxane; the defoamer is selected from poloxamer 188.

[0038] (5) Coating and leveling The obtained coating was applied to the surface of a PET film using a slot coating method, with the wet film thickness controlled at 5 μm, and leveled at 58°C for 1.8 min.

[0039] (6) UV curing Irradiation for 5 seconds under ultraviolet light intensity of 95mW / cm² and wavelength of 300nm, with a curing energy of 700mJ / cm², resulted in a high-transparency, wear-resistant fluorinated coating with a thickness of 3μm.

[0040] Example 3 (1) Preparation of fluorinated polyurethane acrylate prepolymer Weigh out 68g of diisocyanate, 48g of polycarbonate diol, 5g of 2,3-dihydroxysuccinyl hydrazine (CAS: 292644-27-0), 0.5g of 2,7-dihydroxy-9-fluorenone (CAS: 42523-29-5), and 9g of fluorinated alcohol by weight and add them to a reaction vessel. React at 82℃ for 2.2h. Then add 11g of hydroxyethyl acrylate (HEA) for end-capping reaction for 0.9h to obtain fluorinated polyurethane acrylate prepolymer. The diisocyanate is a combination of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) (mass ratio IPDI:HDI = 1:0.8); the polycarbonate diol has a molecular weight of 1300 g / mol and a hydroxyl value of 120 mg KOH / g; the fluorinated alcohol is perfluoroalkyl ethanol with a carbon chain length of C9.

[0041] (2) Preparation of UV coating base material Add 52g of the above prepolymer to the reaction vessel, add 42g of reactive diluent at 50°C, and stir for 35 minutes to make the system homogeneous. The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:1.1.

[0042] (3) Introduction of functional components Add 7g of fluorine-containing active monomer and 6.5g of photoinitiator to the system obtained in step (2), and continue stirring for 22min; The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 40 wt% and a molecular weight of 650; the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO in a mass ratio of 1:1.8.

[0043] (4) Additive regulation Add 0.7g of leveling agent and 0.5g of defoamer, disperse at 1800rpm for 18min, and filter through a 4μm filter membrane; The leveling agent is selected from polydimethylsiloxane; the defoamer is selected from polydimethylsiloxane.

[0044] (5) Coating and leveling The obtained coating was applied to the surface of a PET film using a wire rod coating method, with the wet film thickness controlled at 7 μm, and leveled at 65°C for 2.5 min.

[0045] (6) UV curing Irradiation for 7 seconds under ultraviolet light intensity of 110mW / cm² and wavelength of 380nm, with a curing energy of 1000mJ / cm², resulted in a high-transparency, wear-resistant fluorinated coating with a thickness of 4.5μm.

[0046] Example 4 (1) Preparation of fluorinated polyurethane acrylate prepolymer Weigh out the following ingredients by weight: 80g of diisocyanate, 56g of polycarbonate diol, 6g of 2,3-dihydroxysuccinyl hydrazine (CAS: 292644-27-0), 0.6g of 2,7-dihydroxy-9-fluorenone (CAS: 42523-29-5), and 10g of fluorinated alcohol. Add them to a reaction vessel and react at 85°C for 2.5h. Then add 12g of hydroxyethyl acrylate (HEA) for end-capping reaction for 1h to obtain fluorinated polyurethane acrylate prepolymer. The diisocyanate is hexamethylene diisocyanate (HDI) (mass ratio IPDI:HDI=1:1); the polycarbonate diol has a molecular weight of 1500 g / mol and a hydroxyl value of 140 mg KOH / g; the fluorinated alcohol is perfluoroalkyl ethanol with a carbon chain length of C10.

[0047] (2) Preparation of UV coating base material Add 55g of the above prepolymer to the reaction vessel, add 45g of reactive diluent at 55°C, and stir for 40 minutes to make the system homogeneous. The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:1.2.

[0048] (3) Introduction of functional components Add 8g of fluorine-containing active monomer and 7g of photoinitiator to the system obtained in step (2), and continue stirring for 25 minutes; The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 45 wt% and a molecular weight of 800; the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO in a mass ratio of 1:2.

[0049] (4) Additive regulation Add 0.8g of leveling agent and 0.6g of defoamer, disperse at 2000rpm for 20min, and filter through a 5μm filter membrane; The leveling agent is selected from polyether-modified polydimethylsiloxane; the defoamer is selected from poloxamer 188.

[0050] (5) Coating and leveling The obtained coating was applied to the surface of a PET film using a slot coating method, with the wet film thickness controlled at 8 μm, and leveled at 70°C for 3 min.

[0051] (6) UV curing Irradiation for 8 seconds under ultraviolet light intensity of 120mW / cm² and wavelength of 420nm, with a curing energy of 1200mJ / cm², resulted in a high-transparency, wear-resistant fluorinated coating with a thickness of 5μm.

[0052] Comparative Example 1 (1) Preparation of fluorinated polyurethane acrylate prepolymer Weigh out 40g of diisocyanate, 29g of polycarbonate diol, and 6g of fluorinated alcohol by mass and add them to the reactor. React at 75°C for 1.5h. Then add 8g of hydroxyethyl acrylate (HEA) and perform a capping reaction for 0.5h to obtain a fluorinated polyurethane acrylate prepolymer. The diisocyanate is isophorone diisocyanate IPDI (mass ratio IPDI:HDI=1:0); the polycarbonate diol has a molecular weight of 800 g / mol and a hydroxyl value of 70 mg KOH / g; the fluorinated alcohol is perfluoroalkyl ethanol with a carbon chain length of C6.

[0053] (2) Preparation of UV coating base material Add 40g of the above prepolymer to the reaction vessel, add 30g of reactive diluent at 40°C, and stir for 20 minutes to make the system uniform. The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:0.6.

[0054] (3) Introduction of functional components Add 4g of fluorine-containing active monomer and 4g of photoinitiator to the system obtained in step (2), and continue stirring for 15 minutes; The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 25 wt% and a molecular weight of 300; the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO in a mass ratio of 1:1.

[0055] (4) Additive regulation Add 0.3g of leveling agent and 0.2g of defoamer, disperse at 1000rpm for 10min, and filter through a 1μm filter membrane; The leveling agent is selected from polydimethylsiloxane; the defoamer is selected from polydimethylsiloxane.

[0056] (5) Coating and leveling The obtained coating was applied to the surface of a PET film by wire bar coating, with the wet film thickness controlled at 4 μm, and leveled at 50°C for 1 min.

[0057] (6) UV curing Irradiation for 3 seconds under ultraviolet light intensity of 80mW / cm² and wavelength of 250nm, with a curing energy of 500mJ / cm², resulted in a high-transparency, wear-resistant fluorinated coating with a thickness of 2μm.

[0058] Comparative Example 2 (1) Preparation of fluorinated polyurethane acrylate prepolymer Weigh out 40g of diisocyanate, 29g of polycarbonate diol, 0.2g of 2,7-dihydroxy-9-fluorenone (CAS: 42523-29-5), and 6g of fluorinated alcohol by weight and add them to the reactor. React at 75℃ for 1.5h. Then add 8g of hydroxyethyl acrylate (HEA) for end-capping reaction for 0.5h to obtain fluorinated polyurethane acrylate prepolymer. The diisocyanate is isophorone diisocyanate IPDI (mass ratio IPDI:HDI=1:0); the polycarbonate diol has a molecular weight of 800 g / mol and a hydroxyl value of 70 mg KOH / g; the fluorinated alcohol is perfluoroalkyl ethanol with a carbon chain length of C6.

[0059] (2) Preparation of UV coating base material Add 40g of the above prepolymer to the reaction vessel, add 30g of reactive diluent at 40°C, and stir for 20 minutes to make the system uniform. The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:0.6.

[0060] (3) Introduction of functional components Add 4g of fluorine-containing active monomer and 4g of photoinitiator to the system obtained in step (2), and continue stirring for 15 minutes; The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 25 wt% and a molecular weight of 300; the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO in a mass ratio of 1:1.

[0061] (4) Additive regulation Add 0.3g of leveling agent and 0.2g of defoamer, disperse at 1000rpm for 10min, and filter through a 1μm filter membrane; The leveling agent is selected from polydimethylsiloxane; the defoamer is selected from polydimethylsiloxane.

[0062] (5) Coating and leveling The obtained coating was applied to the surface of a PET film by wire bar coating, with the wet film thickness controlled at 4 μm, and leveled at 50°C for 1 min.

[0063] (6) UV curing Irradiation for 3 seconds under ultraviolet light intensity of 80mW / cm² and wavelength of 250nm, with a curing energy of 500mJ / cm², resulted in a high-transparency, wear-resistant fluorinated coating with a thickness of 2μm.

[0064] Comparative Example 3 (1) Preparation of fluorinated polyurethane acrylate prepolymer Weigh out the following ingredients by weight: 40g of diisocyanate, 29g of polycarbonate diol, 2g of 2,3-dihydroxysuccinyl hydrazine (CAS: 292644-27-0), and 6g of fluorinated alcohol. Add them to a reaction vessel and react at 75°C for 1.5h. Then add 8g of hydroxyethyl acrylate (HEA) for end-capping reaction for 0.5h to obtain fluorinated polyurethane acrylate prepolymer. The diisocyanate is isophorone diisocyanate IPDI (mass ratio IPDI:HDI=1:0); the polycarbonate diol has a molecular weight of 800 g / mol and a hydroxyl value of 70 mg KOH / g; the fluorinated alcohol is perfluoroalkyl ethanol with a carbon chain length of C6.

[0065] (2) Preparation of UV coating base material Add 40g of the above prepolymer to the reaction vessel, add 30g of reactive diluent at 40°C, and stir for 20 minutes to make the system uniform. The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:0.6.

[0066] (3) Introduction of functional components Add 4g of fluorine-containing active monomer and 4g of photoinitiator to the system obtained in step (2), and continue stirring for 15 minutes; The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 25 wt% and a molecular weight of 300; the photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO in a mass ratio of 1:1.

[0067] (4) Additive regulation Add 0.3g of leveling agent and 0.2g of defoamer, disperse at 1000rpm for 10min, and filter through a 1μm filter membrane; The leveling agent is selected from polydimethylsiloxane; the defoamer is selected from polydimethylsiloxane.

[0068] (5) Coating and leveling The obtained coating was applied to the surface of a PET film by wire bar coating, with the wet film thickness controlled at 4 μm, and leveled at 50°C for 1 min.

[0069] (6) UV curing Irradiation for 3 seconds under ultraviolet light intensity of 80mW / cm² and wavelength of 250nm, with a curing energy of 500mJ / cm², resulted in a high-transparency, wear-resistant fluorinated coating with a thickness of 2μm.

[0070] Test method: 1. Light transmittance test The transmittance of the sample was measured using a UV-Vis spectrophotometer at a wavelength of 550 nm.

[0071] Test environment: Temperature 23±2℃, humidity 50±5%.

[0072] Each sample was tested three times, and the average value was taken.

[0073] 2. Pencil Hardness Test Tested according to ASTM D 3363 standard.

[0074] Test steps: Place the coating sample on a horizontal platform. Use 6H to 6B series pencils, applying pressure at a 45° angle. Driven by approximately 6mm of stroke Record the highest hardness level that does not produce scratches 3. Abrasion resistance test Using steel wool friction method: Load capacity: 500g Friction medium: Grade 0000 steel wool Number of reciprocating friction cycles: 500 Evaluation criteria: No obvious scratches: Excellent Minor scratches: Good Obvious scratches: Poor 4. Contact Angle Test The water contact angle was measured using a contact angle measuring instrument. Droplet volume: 5 μL Test time: Read within 5 seconds Each sample was tested 5 times, and the average value was taken. 5. Adhesion test The 100-grid test (GB / T 9286) is adopted: Stroke spacing: 1mm Observe the degree of detachment after peeling off the tape. Level rating: Level 0 (best) ~ Level 5 (worst) 6. Haze Test Tested using a haze meter (ASTM D 1003): Test wavelength: 550nm Take the average of 3 tests. Test results: Table 1 Test Results

[0075] Test data shows that the UV-functional fluorinated coating prepared by this invention is superior to the comparative example in all key indicators such as light transmittance, haze, hardness, water contact angle, adhesion, and abrasion resistance. The core innovation of this scheme is the introduction of 2,3-dihydroxysuccinyl hydrazide and 2,7-dihydroxy-9-fluorenone in the prepolymer preparation stage. The synergistic effect of the two optimizes the polyurethane chain structure and cross-linking network: the hydrazide group strengthens the intermolecular forces, improves the coating density and interfacial adhesion, and the rigid unit of fluorenone enhances the coating hardness and abrasion resistance. At the same time, it effectively inhibits the phase separation of fluorinated components, ensuring the optical uniformity of the coating. This fundamentally solves the technical bottleneck of traditional PET coatings, which struggle to achieve both high light transmittance and high abrasion resistance, and the poor compatibility of fluorinated systems, thus achieving simultaneous optimization of optical performance, mechanical performance, and surface protection performance.

[0076] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film, characterized in that, Includes the following steps: (1) Preparation of fluorinated polyurethane acrylate prepolymer According to the mass fractions, 40-80 parts of diisocyanate, 29-56 parts of polycarbonate diol, 2-6 parts of 2,3-dihydroxysuccinyl hydrazine, 0.2-0.6 parts of 2,7-dihydroxy-9-fluorenone, and 6-10 parts of fluorinated alcohol are added to a reaction vessel and reacted at 75-85°C for 1.5-2.5 h; then 8-12 parts of hydroxyethyl acrylate (HEA) are added for end-capping reaction for 0.5-1 h to obtain fluorinated polyurethane acrylate prepolymer. (2) Preparation of UV coating base material Add 40-55 parts of the above prepolymer to a reaction vessel, add 30-45 parts of reactive diluent at 40-55°C, and stir for 20-40 minutes to make the system uniform. (3) Introduction of functional components Add 4-8 parts of fluorine-containing active monomer and 4-7 parts of photoinitiator to the system obtained in step (2), and continue stirring for 15-25 minutes; (4) Additive regulation Add 0.3-0.8 parts of leveling agent and 0.2-0.6 parts of defoamer, disperse at 1000-2000 rpm for 10-20 min, and filter through a 1-5 μm filter membrane; (5) Coating and leveling The obtained coating is applied to the surface of PET film by wire bar or slit coating, with the wet film thickness controlled at 4-8 μm, and leveled at 50-70℃ for 1-3 min. (6) UV curing Irradiation with ultraviolet light at 80–120 mW / cm² for 3–8 seconds cures to form a high-transmittance, wear-resistant fluorine-containing coating with a thickness of 2–5 μm.

2. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The diisocyanate is one or both of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI), with a mass ratio of IPDI:HDI = 1:(0-1).

3. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The polycarbonate diol has a molecular weight of 800–1500 g / mol and a hydroxyl value of 70–140 mg KOH / g.

4. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The fluorinated alcohol is a perfluoroalkyl ethanol with a carbon chain length of C6 to C10.

5. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The active diluent is a polyfunctional acrylate, which consists of trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:(0.6-1.2).

6. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The fluorinated active monomer is a fluorinated acrylate monomer with a fluorine content of 25-45 wt% and a molecular weight of 300-800.

7. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The photoinitiator system is 2-hydroxy-2-methyl-1-phenyl-1-propanone and TPO, with a mass ratio of 1:(1-2).

8. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The leveling agent is selected from polydimethylsiloxane or polyether-modified polydimethylsiloxane.

9. The method for preparing a UV-functionalized fluorinated coating material for high-transparency and wear-resistant PET film according to claim 1, characterized in that: The defoamer is selected from polydimethylsiloxane or poloxamer 188.

10. The method for preparing a UV-functionalized fluorinated coating material for a high-transparency, wear-resistant PET film according to claim 1, characterized in that: In step (6), the ultraviolet light wavelength is 250-420nm and the curing energy is 500-1200mJ / cm².

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