Photochromic dye grafted nanoparticle composite film photochromic lens and preparation method thereof

Abstract

The invention relates to a photochromic lens with a photochromic dye grafted nanoparticle composite film layer and a preparation method of the photochromic lens, and belongs to the technical field of optical lenses. The photochromic lens comprises a lens base material, a priming coat, a photochromic dye grafted nanoparticle composite film layer and a protective layer which are sequentially stacked from bottom to top, wherein chemical bond grafting is formed between the photochromic dye and the surfaces of the gold / silver nanoparticles through sulfydryl or carboxyl at the tail end of a molecule of the photochromic dye. The localized surface plasmon resonance effect of the covalent grafting structure and the nanoparticles synergistically solves the bottlenecks of easy agglomeration, low loading capacity and slow response of the dye in the traditional technology. The lens disclosed by the invention has the characteristics of extremely fast color-changing response, high color fading efficiency, high mechanical strength, good environmental stability and the like, and the comprehensive performance and the service life of the color-changing lens are remarkably improved and prolonged.

Description

Technical Field

[0001] This invention belongs to the field of optical lens technology, and relates to a photochromic lens with a composite film of photochromic dye grafted with nanoparticles and its preparation method. Background Technology

[0002] Photochromic lenses provide visual comfort and protection by altering light transmittance under illumination. Currently, the mainstream technologies for achieving photochromic functionality in lenses include substrate doping, surface coating, and nanocomposite technologies developed based on these methods; however, these methods still have certain limitations.

[0003] The substrate doping method involves directly dispersing spiropyran or spiroxazine photochromic dyes in resin monomers, followed by polymerization to form a uniform color-changing substrate. Chinese patent CN 116224622 B improves overall performance by constructing a bilayer structure of substrate and coating. However, this method has inherent bottlenecks. For example, the uniformity of dye dispersion in the polymer network is difficult to control precisely, resulting in insufficient color-changing depth and limited differences in indoor and outdoor transmittance. Furthermore, the poor compatibility between the dye and high-refractive-index resin can easily lead to performance instability or material defects.

[0004] Surface coating methods typically employ film-changing technology (such as Trans-bonding™ process) to coat the surface of a lens substrate with a coating containing photochromic dyes and then cure it into a film using crosslinking agents such as isocyanates, as illustrated in Chinese patent CN 115521495 A. The challenge lies in the fact that the bonding between the coating and the substrate largely relies on physical adsorption or limited chemical bonding, resulting in insufficient adhesion and easy peeling under mechanical friction or harsh environments. To obtain sufficient photochromic effects, it is often necessary to increase the coating thickness (usually ≥5μm), but this may affect the optical quality and mechanical properties of the lens. In addition, the dyes in the coating are directly exposed to the environment and are prone to photochemical degradation under high temperature or long-term ultraviolet radiation, leading to a decrease in durability.

[0005] Researchers have explored the introduction of nanomaterials into color-changing systems. However, in nanocomposite technology, nanoparticles and dye molecules are mostly simple physical blends, lacking a stable chemical bond. During long-term use, nanoparticles are prone to aggregation, which not only fails to effectively enhance performance but may also hinder the isomerization process of dye molecules, resulting in a slower color-changing response.

[0006] In summary, existing photochromic lenses primarily achieve their color-changing function through substrate doping or surface coating, but they suffer from the following technical bottlenecks: In traditional coating techniques, the adhesion between the photochromic dye and the substrate is insufficient, leading to easy detachment after long-term use; the color-changing depth is insufficient, and the dye concentration is limited, resulting in limited differences in light transmittance between indoor and outdoor environments; the color-changing response speed is slow, especially on high-refractive-index substrates where performance degradation is significant; and durability is poor, with the coating easily affected by environmental temperature and humidity, leading to performance degradation after long-term use. A single coating structure makes it difficult to simultaneously achieve both color-changing depth and fading rate. Therefore, there is an urgent need to develop a composite film for photochromic lenses with strong adhesion, fast response speed, good environmental adaptability, and long-lasting performance, as well as its preparation method. Summary of the Invention

[0007] The purpose of this invention is to provide a photochromic dye-grafted nanoparticle composite film photochromic lens and its preparation method. By covalently grafting photochromic dyes with thiol or carboxyl groups onto the surface of gold or silver nanoparticles, a structurally stable composite functional unit is constructed, fundamentally solving the bottlenecks of traditional photochromic lenses in terms of performance and environmental adaptability.

[0008] A photochromic lens with a photochromic dye-grafted nanoparticle composite film layer, wherein the photochromic lens comprises, from bottom to top, a lens substrate, a base coating layer, a photochromic dye-grafted nanoparticle composite film layer, and a protective layer, which are stacked sequentially. The photochromic dye is grafted onto the surface of nanoparticles by forming chemical bonds through the thiol or carboxyl groups at the ends of its molecules.

[0009] Gold nanoparticles generate the LSPR effect under ultraviolet light irradiation, which enhances the local electric field strength, improves the absorption efficiency of photochromic dyes to ultraviolet light, accelerates the ring-opening / ring-closing isomerization reaction of dye molecules, and thus shortens the color change response time.

[0010] Thiol / carboxyl groups form stable MS (M=Au / Ag) or MOC chemical bonds with the surface of nanoparticles, avoiding aggregation caused by van der Waals forces between dye molecules, ensuring uniform dispersion of dye in the composite film layer, and improving the color change depth.

[0011] As a preferred embodiment of the present invention, the photochromic dye is one or two of spiropyran or spiroxazine dyes that have undergone thiol or carboxylation treatment.

[0012] As a preferred embodiment of the present invention, the nanoparticles are one or both of gold nanoparticles and silver nanoparticles.

[0013] As a preferred embodiment of the present invention, the lens substrate is one of polycarbonate, carbamate, or polyurethane, and has a thickness of 1.2~2.0 mm.

[0014] As a preferred embodiment of the present invention, the coating of the base layer is a mixture of polyurethane and silane coupling agent at a mass ratio of 99:1, and the thickness of the base layer is 0.5~1.5μm.

[0015] As a preferred technical solution of the present invention, the formulation of the photochromic dye grafted nanoparticle composite film coating liquid includes the following components by weight: 5-15 parts of photochromic dye grafted nanoparticles, 20-40 parts of polyether polyol, 15-35 parts of isocyanate, 0.1-1 parts of catalyst and 25-45 parts of solvent. The photochromic dye-grafted nanoparticle solution contains 0.5~1.5 wt% nanoparticles. The polyether polyol is one or more selected from polytetrahydrofuran ether diol (PTMEG), propylene glycol polyether, trimethylolpropane polyether, and ethylene glycol polyether (PEG); The isocyanate is one or more selected from toluene diisocyanate (TDI), dicyclohexylmethane diisocyanate (HMDI), and diphenylmethane diisocyanate (MDI); The catalyst is one or more of dibutyltin dicarboxylate, dimethylaminoethyl ether, pentamethyldiethylenetriamine, and stannous octoate; The solvent is one or more of dimethylformamide, methylpyrrolidone, cyclohexanone, and propylene glycol methyl ether; The thickness of the photochromic dye-grafted nanoparticle composite film is 5~20 μm.

[0016] As a preferred technical solution of the present invention, the preparation process of the photochromic dye grafted nanoparticle composite film coating liquid is as follows: the raw materials in the composite film coating liquid formula are stirred and mixed at 50 °C for 1 h, and then vacuum degassed for 30 min. The viscosity of the coating liquid is controlled at 500~800 mPa・s to obtain the composite film coating liquid.

[0017] As a preferred embodiment of the present invention, the protective layer is made of polyurethane acrylate and has a thickness of 15~25μm.

[0018] A method for preparing a photochromic lens with a composite film of photochromic dye grafted with nanoparticles, the specific steps of which are as follows: S9-1. Preparation of the base coating: The lens substrate is pretreated, and the base coating is applied to the surface of the pretreated lens substrate by dip coating process. After curing at 110~130℃ for 1~3 h, the base coating is obtained. S9-2. Preparation of photochromic dye-grafted gold nanoparticle composite film: The composite film coating liquid is applied to the surface of the base layer by spin coating process at a speed of 1500~2500 rpm for 20~40s. After heat curing at 95~135℃ for 30~180min, the photochromic dye-grafted gold nanoparticle composite film is obtained. S9-3. Preparation of the protective layer: Polyurethane acrylate is coated onto the surface of the photochromic dye-grafted gold nanoparticle composite film, and then UV cured for 2-5 seconds at a power of 400-600 mW / cm². 2 The protective layer is obtained.

[0019] As a preferred embodiment of the present invention, the pretreatment step is alkaline washing or plasma treatment; The alkaline pretreatment step involves placing the lens substrate in a sodium hydroxide solution with a mass fraction of 20% to 30% and ultrasonically cleaning it for 5 to 20 minutes. The ultrasonic power is 20 to 90 W and the ultrasonic frequency is 30 to 80 kHz. Then, it is washed with deionized water and dried to obtain the pretreated lens substrate. The plasma pretreatment step involves placing the substrate in a plasma processor for 3-10 minutes with a plasma power of 50-150W to obtain the pretreated lens substrate.

[0020] The beneficial effects of this invention are: (1) Regarding photochromic performance, firstly, the response speed of the lens prepared by this invention is significantly improved. This is due to the significant local surface plasmon resonance effect of gold / silver nanoparticles and their high specific surface area, which greatly improves the absorption and conversion efficiency of the composite film for ultraviolet light. The transmittance can be reduced to 8.3% (reaching CAT 3 standard) within 25 seconds under ultraviolet irradiation, which is about 64% faster than the response speed of traditional coating technology (such as Example 1 of CN 116224622 B, which requires 70s). Secondly, the fading recovery is highly efficient. After the light irradiation stops, the resistance to the movement of dye molecules grafted on the surface of nanoparticles decreases, and the isomerization recovery rate is accelerated. The transmittance can be restored to more than 85% in just 2 minutes, which is about 71% more efficient than traditional methods such as substrate doping (such as Comparative Example 1 of CN 115521495 A).

[0021] (2) Regarding the mechanical strength and durability of the film, firstly, the adhesion is significantly improved. The covalent grafting structure and optimized primer coating process make the film bonded to the lens substrate extremely firmly. The cross-cut test results showed no peeling, and the interfacial shear strength reached 5.2 MPa, which is about 86% higher than that of traditional physical adsorption coatings (about 2.8 MPa). Secondly, the abrasion resistance is superior. After 1000 cycles of steel wool rubbing, the lens haze changed by only 0.5%, which is better than the industry standard and existing comparative technologies, demonstrating excellent daily use tolerance. Furthermore, the cycle life is extended. The rigid framework of gold nanoparticles plays a stabilizing and protective role for dye molecules, significantly inhibiting photo-fatigue degradation. The color-changing cycle life of the composite film can be increased to more than 10,000 cycles, greatly improving reliability. (3) Regarding environmental adaptability and stability, firstly, it exhibits stable performance over a wide temperature range. In extreme temperature cycling tests ranging from -20℃ to 80℃, the color change depth fluctuation of the composite film is less than 5%. The gold nanoparticle grafted structure effectively inhibits the thermal decomposition of dyes such as spiropyran at high temperatures, and its open-ring structure decomposition rate is significantly reduced from approximately 25% in the traditional state to less than 3%. Secondly, it has strong resistance to solvent erosion, and the covalently bonded dense structure effectively prevents solvent penetration. After being repeatedly wiped 100 times with 75% ethanol, the light transmittance changes by less than 2%, which is significantly better than the ungrafted coating (the change can reach 15%), ensuring the durability of the lens's performance under different usage environments. Attached Figure Description

[0022] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a structural diagram of the photochromic lens obtained in Embodiment 1 of the present invention. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0025] It should be noted that, unless otherwise specified, the present invention does not specifically limit the source of the raw materials used in the following embodiments. Commercially available products or products prepared by conventional preparation methods that are well known to those skilled in the art can be used. Experimental methods that do not specify specific conditions are all conventional methods and conventional conditions well known in the art.

[0026] Example 1 A photochromic lens with a photochromic dye-grafted nanoparticle composite film layer, wherein the photochromic lens comprises, from bottom to top, a lens substrate, a base coating layer, a photochromic dye-grafted nanoparticle composite film layer, and a protective layer, which are stacked sequentially. The photochromic dye is mercapto-spiropyran-grafted gold nanoparticles.

[0027] A method for preparing a photochromic lens with a composite film of photochromic dye grafted with nanoparticles, the specific steps of which are as follows: S9-1. Substrate pretreatment: The CR-39 substrate (70 mm in diameter and 4 mm in center thickness) was ultrasonically cleaned in 25% NaOH solution for 10 min with a power of 80 W and an ultrasonic frequency of 50 kHz. After washing with water, it was dried at 120 ℃ for 2 h to obtain the pretreated substrate. S9-2, Preparation of the base coating: Apply polyurethane base coating liquid to the surface of the pretreated substrate at a lifting speed of 1.8 mm / s and cure at 130℃ for 3 h to form a base coating with a thickness of 0.8 μm; The polyurethane primer has a solid content of 15% and contains 1 wt% γ-glycidoxypropyltrimethoxysilane. S9-3. Preparation of photochromic dye-grafted gold nanoparticle composite film: The composite film coating liquid is applied to the surface of the base layer by spin coating process at a speed of 2000 rpm for 30 s. After heat curing at 110℃ for 90 min, the photochromic dye-grafted gold nanoparticle composite film with a thickness of 15 μm is obtained. The preparation steps of thiolized spiropyran-grafted gold nanoparticles are as follows. S9-31. Heat 1000 mL of 10 mM HAuCl4 solution to boiling, quickly add 100 mL of 38.8 mM trisodium citrate solution, keep boiling for 15 min, and after cooling, obtain an AuNPs solution with a particle size of 15 ± 2 nm. S9-32. Thiolized spiropyran (HS-SP) was added to the AuNPs solution, stirred in a water bath at 32°C for 2 h, and centrifuged for 10 min to remove ungrafted dye. The centrifuge speed was set to 10000 rpm. Subsequently, it was dispersed in N,N-dimethylformamide to obtain a solution of thiolated spiropyran-grafted gold nanoparticles containing 1.5 wt% AuNPs. The dye grafting rate was determined to be 85% by UV spectrophotometer. Among them, the thiolated spiropyran (HS-SP) was 6-mercapto-8-methoxy-1',3',3'-trimethylspiro[3,4-dihydro-2H-1-benzopyran-2,2'-indole], purchased from TCI (Shanghai) Chemical Industry Development Co., Ltd., with the supply number HS-SP-01.

[0028] The formulation of the composite film coating solution includes the following components by weight: 10 parts of mercapto-spiropyran-grafted gold nanoparticle solution, 30 parts of PPG-3000, 25 parts of HMDI, 0.5 parts of dibutyltin dimethylsilyl silicate, and 35 parts of dimethylformamide. The preparation method of the composite membrane coating solution is as follows: the raw materials in the composite membrane coating solution formula are stirred and mixed at 50 °C for 1 h, then vacuum degassed for 30 min, and the viscosity of the coating solution is controlled at 650 mPa・s to obtain the composite membrane coating solution.

[0029] S9-4. Preparation of the protective layer: Coat with a protective liquid containing 60 parts TMPTA and 20 parts BRO11300 oligomer, and apply at 500mW / cm. 2 UV curing for 4 seconds forms a protective layer with a thickness of 20 μm, resulting in the photochromic dye-grafted nanoparticle composite film photochromic lens.

[0030] Example 2 A photochromic lens with a photochromic dye-grafted nanoparticle composite film layer, wherein the photochromic lens comprises, from bottom to top, a lens substrate, a base coating layer, a photochromic dye-grafted nanoparticle composite film layer, and a protective layer, which are stacked sequentially. The photochromic dye is mercapto-hydroxyspiroxazine-grafted gold nanoparticles.

[0031] A method for preparing a photochromic lens with a composite film of photochromic dye grafted with nanoparticles, the specific steps of which are as follows: S9-1. Substrate pretreatment: The PC substrate (refractive index 1.586) is subjected to plasma treatment for 5 minutes at a power of 100W to obtain a pretreated substrate with a surface roughness Ra=0.2μm. S9-2, Preparation of the base coating: Apply polyurethane base coating liquid to the surface of the pretreated substrate at a lifting speed of 1.8 mm / s and cure at 120℃ for 2 h to form a base coating with a thickness of 1.2 μm; The polyurethane primer has a solid content of 15% and contains 1 wt% γ-glycidoxypropyltrimethoxysilane. S9-3. Preparation of photochromic dye-grafted gold nanoparticle composite film: The composite film coating liquid is applied to the surface of the base layer by spin coating process at a speed of 2500 rpm for 30 s. After heat curing at 120℃ for 80 min, the photochromic dye-grafted gold nanoparticle composite film with a thickness of 18 μm is obtained. The preparation steps of thiolated spiroxazine-grafted gold nanoparticles are as follows. S9-31. Heat 1000 mL of 10 mM HAuCl4 solution to boiling, quickly add 100 mL of 38.8 mM trisodium citrate solution, keep boiling for 15 min, and after cooling, obtain an AuNPs solution with a particle size of 15 ± 2 nm. S9-32. Thiolized spiroxazine (HS-SO) was added to the AuNPs solution, stirred in a water bath at 32°C for 2 h, and centrifuged for 10 min to remove ungrafted dye. The centrifuge speed was set to 10000 rpm. Subsequently, it was dispersed in N,N-dimethylformamide to obtain a solution of thiolated spiroxazine-grafted gold nanoparticles containing 1.5 wt% AuNPs. The dye grafting rate was determined to be 88% by UV spectrophotometer. Among them, the thiolated spiroxazine (HS-SO) was 6-mercapto-7-methoxy-1',3',3'-trimethylspiro[indole-2,3'-benzoxazine], purchased from TCI (Shanghai) Chemical Industry Development Co., Ltd., with supply number HS-S0-01.

[0032] The composite film coating solution is formulated with the following components by weight: 10 parts of mercapto-spiroxazine-grafted gold nanoparticle solution, 30 parts of PPG-3000, 25 parts of HMDI, 0.5 parts of dibutyltin dimethylsilyl silicate, and 35 parts of dimethylformamide. The preparation method of the composite membrane coating solution is as follows: the raw materials in the composite membrane coating solution formula are stirred and mixed at 50 °C for 1 h, then vacuum degassed for 30 min, and the viscosity of the coating solution is controlled at 650 mPa・s to obtain the composite membrane coating solution.

[0033] S9-4. Preparation of the protective layer: Coat with a protective liquid containing 60 parts TMPTA and 20 parts BRO11300 oligomer, and apply at 500mW / cm. 2 UV curing for 4 seconds forms a protective layer with a thickness of 20 μm, resulting in the photochromic dye-grafted nanoparticle composite film photochromic lens.

[0034] Example 3 The difference between this embodiment and Embodiment 1 is that the photochromic dye uses silver nanoparticles (AgNPs, particle size 20~30nm) + mercaptoethylamine as the linker to graft spiropyran, while the rest is the same as in Embodiment 1.

[0035] The preparation method of the photochromic dye is as follows: S9-31, Synthesis of Silver Nanoparticles (AgNPs): Add 1000 mL of deionized water to a three-necked flask, heat to 85 °C with magnetic stirring, and purge air with nitrogen gas. Quickly add 100 mL of 10 mM AgNO3 solution and stir continuously for 5 minutes until the solution turns pale yellow. Slowly add 80 mL of 50 mM sodium citrate solution at a rate of 2 mL / min, maintaining the temperature at 85°C and stirring for 30 minutes. The solution color gradually changes from pale yellow to bright yellow, and finally to pale brown. Stop heating and allow to cool naturally to room temperature. Measure the particle size using a dynamic light scattering (DLS) instrument to determine that it is 20–30 nm. Measure the UV absorption peak (characteristic peak approximately 410 nm) using a UV-Vis spectrophotometer. Set the solution aside for later use. S9-32, mercaptoethylamine (MEA) modified silver nanoparticles: Place 500 mL of AgNPs solution in a beaker, maintain the temperature in a 30°C water bath, and stir magnetically (500 rpm). Add 50 mL of 1 mM mercaptoethylamine solution dropwise, and continue stirring for 2 hours after the addition is complete. Transfer the mixture to a centrifuge tube and centrifuge at 10,000 rpm for 15 minutes to remove unreacted mercaptoethylamine. Discard the supernatant, resuspend the precipitate in deionized water, and repeat the centrifugation-resuspending operation 3 times. Finally, disperse the MEA-modified AgNPs in 200 mL of N,N-dimethylformamide (DMF) for later use.

[0036] S9-33, spiropyran (SP) grafted onto MEA-AgNPs surface: 200 mL of MEA-AgNPs / DMF dispersion was transferred to a three-necked flask and kept at a constant temperature of 35 °C in a water bath with magnetic stirring (600 rpm). 30 mL of 1 mM HS-SP solution was slowly added, and the mixture was stirred for 3 hours. After the reaction was completed, the mixture was centrifuged at 10,000 rpm for 10 minutes and the supernatant was discarded. The precipitate was resuspended in DMF, centrifuged and washed twice, and finally dispersed in 100 mL of DMF to obtain the photochromic dye solution containing 1.5 wt% AgNPs.

[0037] Example 4 The difference between this embodiment and Embodiment 1 is that the photochromic dye uses a carboxyl grafting system (using 2,3-dimercaptosuccinic acid, grafted with spiropyran via EDC / NHS coupling reaction), while the rest is the same as in Embodiment 1.

[0038] The preparation method of the photochromic dye is as follows: S9-31, 2,3-dimercaptosuccinic acid (DMSA) modified AuNPs: Take 500 mL of AuNPs solution, adjust the pH to 7.0 with 0.1 M NaOH, keep the temperature constant in a 30°C water bath, and stir magnetically (500 rpm). Add 40 mL of 2 mM DMSA solution dropwise, and continue stirring for 2.5 hours after the addition is complete; centrifuge at 10,000 rpm for 15 minutes and discard the supernatant; resuspend the precipitate with deionized water, centrifuge and wash 3 times, and finally disperse the DMSA-modified AuNPs (DMSA-AuNPs) in 200 mL of DMF for later use; S9-32, EDC / NHS activated carboxyl groups: Transfer 200 mL of DMSA-AuNPs / DMF dispersion to a three-necked flask, keep it in a 30°C water bath, and stir magnetically (400 rpm). Add 30 mL of 10 mM EDC solution and 30 mL of 15 mM NHS solution sequentially, and stir to activate for 1.5 hours; during the activation process, monitor the pH of the solution with a pH meter and maintain it at 6.5~7.0; S9-33, mercapto-modified spiropyran grafted onto the surface of activated DMSA-AuNPs: Slowly add 25 mL of 1 mM HS-SP solution to the activated DMSA-AuNPs dispersion and stir in a water bath at 35°C for 3 hours; After the reaction was completed, 500 mL of anhydrous diethyl ether was added to precipitate the product. After standing for 30 minutes, the product was centrifuged at 8000 rpm for 10 minutes and the supernatant was discarded. The precipitate was resuspended in DMF, centrifuged and washed twice, and finally dispersed in 100 mL of DMF to obtain the photochromic dye solution.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that unthiolized spiropyran is used instead of thiolized spiropyran. The unthiolized spiropyran is 8-methoxy-1',3',3'-trimethylspiro[3,4-dihydro-2H-1-benzopyran-2,2'-indole]. All other aspects are the same as in Example 1.

[0040] Comparative Example 2 The difference between this comparative example and Example 2 is that unthiolized spiroxazine is used instead of thiolized spiroxazine. The unthiolized spiroxazine is 7-methoxy-1',3',3'-trimethylspiro[indole-2,3'-benzoxazine]. All other aspects are the same as in Example 1.

[0041] Performance testing Cycle life: Repeat the cycle test of "2 min of UV irradiation (coloring) - 2 min of light protection recovery (fading)". When the color change depth (transmittance after irradiation) rises to 80% of the initial value, stop the test and record the number of cycles to reflect the long-term light fatigue resistance of the lens.

[0042] Wide temperature range stability: The lens was placed in constant temperature chambers at -20℃, 25℃ and 80℃ for 2 hours respectively. The color change depth (transmittance after 2 minutes of irradiation) was tested at each temperature. The maximum fluctuation value (ΔT) of the color change depth at different temperatures and at 25℃ was calculated to reflect the performance stability under extreme temperatures.

[0043] Solvent resistance: The lens surface was repeatedly wiped 100 times at a speed of 1 time / second with a lint-free cotton cloth soaked in 75% ethanol solution under a 500g load. The light transmittance before and after wiping was tested, and the change in light transmittance (ΔT%) was calculated to reflect the performance durability in daily cleaning scenarios.

[0044] The photochromic lenses prepared in the examples and comparative examples were subjected to performance tests, and the test methods are as follows: (1) Color change depth: The transmittance of the lens after being exposed to ultraviolet light for 2 minutes is measured by an instrument and expressed as %; the smaller the value, the deeper the color change. (2) Fading rate: The time required for the transmittance of the lens to recover from the lowest value to more than 80% after the ultraviolet irradiation is stopped; (3) Adhesion: Boil the test piece in boiling water for 1 hour, then use a blade to cut 100 small squares with a side length of 1mm on the surface of the lens, and use tape to stick and pull three times. It is required that no film layer should be peeled off in any square. (4) Impact resistance: The lens is dropped freely from a height of 2 m by a 16g steel ball. If there are no obvious cracks, it is considered qualified; otherwise, it is unqualified. (5) Abrasion resistance: According to the haze test method in GB / T2410, 000# steel wool is repeatedly rubbed on the lens surface 1000 times under a weight of 750g. The haze value of the lens before and after abrasion is tested. The change in haze value ≤0.8 is considered as qualified, otherwise it is unqualified.

[0045] Color change depth (%) Fading rate Adhesion Impact resistance abrasion resistance Cycle life (times) Wide temperature range stability (ΔT%) Solvent erosion resistance (ΔT%) Example 1 8.3 Light transmittance recovered to 85% in 2 minutes. pass qualified qualified ≥12000 3.2 1.8 Example 2 7.6 2.5 minutes to recover to 82% pass qualified qualified ≥13000 2.8 1.5 Example 3 7.9 The light transmittance recovered to 82% in 2.1 minutes. pass qualified qualified ≥11000 3.5 2 Example 4 8.2 Light transmittance recovered to 85% in 2.6 minutes. Not passed qualified qualified ≥10000 3.8 2.2 Comparative Example 1 10.8 Light transmittance recovered to 85% in 3.0 minutes. pass qualified Unqualified 3200 12.5 15.3 Comparative Example 2 9.6 Light transmittance recovered to 84% in 3.2 minutes. pass qualified Unqualified 3500 18.7 19.6 As can be seen from the above embodiments and comparative data, the photochromic lenses prepared by the present invention have the characteristics of extremely fast color-changing response, high fading efficiency, and high mechanical strength. The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A photochromic lens with a composite film of photochromic dye grafted with nanoparticles, characterized in that, The photochromic lens comprises, from bottom to top, a lens substrate, a base coating, a photochromic dye-grafted nanoparticle composite film, and a protective layer, which are stacked sequentially. The photochromic dye is grafted onto the surface of nanoparticles by forming chemical bonds through the thiol or carboxyl groups at the ends of its molecules.

2. The photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in claim 1, characterized in that, The photochromic dye is one or two of spiropyran or spiroxazine dyes that have undergone thiol or carboxylation treatment.

3. The photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in claim 1, characterized in that, The nanoparticles are one or both of gold nanoparticles and silver nanoparticles.

4. The photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in claim 1, characterized in that, The lens substrate is one of polycarbonate, carbamate, or polyurethane, with a thickness of 1.2~2.0 mm.

5. The photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in claim 1, characterized in that, The base coating is a mixture of polyurethane and silane coupling agent at a mass ratio of 99:1, and the thickness of the base coating is 0.5~1.5μm.

6. The photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in claim 1, characterized in that, The formulation of the photochromic dye-grafted nanoparticle composite film coating liquid comprises the following components by weight: 5-15 parts of photochromic dye-grafted nanoparticle solution, 20-40 parts of polyether polyol, 15-35 parts of isocyanate, 0.1-1 parts of catalyst, and 25-45 parts of solvent. The photochromic dye-grafted nanoparticle solution contains 0.5~1.5 wt% nanoparticles. The polyether polyol is one or more selected from polytetrahydrofuran ether diol (PTMEG), propylene glycol polyether, trimethylolpropane polyether, and ethylene glycol polyether (PEG); The isocyanate is one or more selected from toluene diisocyanate (TDI), dicyclohexylmethane diisocyanate (HMDI), and diphenylmethane diisocyanate (MDI); The catalyst is one or more of dibutyltin dicarboxylate, dimethylaminoethyl ether, pentamethyldiethylenetriamine, and stannous octoate; The solvent is one or more of dimethylformamide, methylpyrrolidone, cyclohexanone, and propylene glycol methyl ether; The thickness of the photochromic dye-grafted nanoparticle composite film is 5~20 μm.

7. The photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in claim 1, characterized in that, The preparation process of the photochromic dye-grafted nanoparticle composite film coating liquid is as follows: the raw materials in the composite film coating liquid formula are stirred and mixed at 50 °C for 1 h, and then vacuum degassed for 30 min. The viscosity of the coating liquid is controlled at 500~800 mPa・s to obtain the composite film coating liquid.

8. The photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in claim 1, characterized in that, The protective layer is made of polyurethane acrylate and has a thickness of 15~25μm.

9. A method for preparing a photochromic lens with a photochromic dye-grafted nanoparticle composite film as described in any one of claims 1 to 8, characterized in that, The specific steps of the preparation method are as follows: S9-1. Preparation of the base coating: The lens substrate is pretreated, and the base coating is applied to the surface of the pretreated lens substrate by dip coating process. After curing at 110~130℃ for 1~3 h, the base coating is obtained. S9-2. Preparation of photochromic dye-grafted gold nanoparticle composite film: The composite film coating liquid is applied to the surface of the base layer by spin coating process at a speed of 1500~2500 rpm for 20~40s. After heat curing at 95~135℃ for 30~180min, the photochromic dye-grafted gold nanoparticle composite film is obtained. S9-3. Preparation of the protective layer: Polyurethane acrylate is coated onto the surface of the photochromic dye-grafted gold nanoparticle composite film, and then UV cured for 2-5 seconds at a power of 400-600 mW / cm². 2 The protective layer is obtained.

10. The method for preparing a photochromic lens with a composite film of photochromic dye grafted with nanoparticles according to claim 9, characterized in that, The pretreatment step is alkaline washing or plasma treatment; The alkaline pretreatment step involves ultrasonically cleaning the lens substrate in a 20%~30% sodium hydroxide solution for 5~20 minutes with an ultrasonic power of 20~90W and an ultrasonic frequency of 30~80kHz, followed by washing with deionized water and drying to obtain the pretreated lens substrate. The plasma pretreatment step involves treating the substrate in a plasma processor for 3~10 minutes with a plasma power of 50~150W to obtain the pretreated lens substrate.

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