Teenager myopia prevention and control lens and manufacturing method and system thereof

Abstract

The invention relates to the technical field of optical lenses, and discloses a myopia prevention and control lens for teenagers and a manufacturing method of the myopia prevention and control lens for teenagers. 10 to 30 parts of polymethyl methacrylate; 0.5 to 2 parts of an ultraviolet absorbent; 1-5 parts of a refractive index regulator; 0.5 to 3 parts of an anti-blue light agent; 0.1 to 1 part of a stabilizer; the siloxane resin is block copolymerized siloxane containing methyl and phenyl substituent groups and has a linear main chain structure, and the molecular weight of the siloxane resin is 10,000-30,000; the polymethyl methacrylate is spherical granular PMMA (polymethyl methacrylate), the particle size is 0.5-5 microns, and the particle size distribution is uniform. According to the invention, excellent optical stability, high-efficiency spectrum filtering performance and long-term durability of the lens are realized through cooperative regulation and control of the composite resin material and a staged thermocuring process.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and particularly to a myopia prevention and control lens for teenagers, its manufacturing method and system. Background Art

[0002] Among the current teenage groups, the problem of myopia shows an increasingly serious trend. Habits such as long-term use of electronic screen devices and high indoor eye use intensity expose the eyes to a large amount of blue light and ultraviolet light, increasing the risk of retinal damage. Ordinary optical lenses can no longer meet the protection requirements. Therefore, there is an urgent need in the market for a new type of lens that not only has blue light protection performance but also maintains structural stability and is not easily aged.

[0003] Currently, some lenses use modified resin materials to improve light transmittance and flexibility; some products use simple ultraviolet absorbers to block ultraviolet light in some bands; individual solutions introduce hot pressing or surface coating technology during processing to improve the smoothness of the appearance and reduce the specular reflectance. These technologies have improved the problems of traditional lenses being fragile and having blurred imaging to a certain extent, and also brought a better visual comfort experience.

[0004] However, there are still some deficiencies in the existing technologies. First of all, although some lenses claim to add anti-blue light components, the measured blocking rate is low in actual tests, and many of them are just dyed, looking yellow but not necessarily actually effective. Secondly, some pursue efficiency blindly during the thermosetting process, with a rapid temperature increase but ignoring the release of material stress, resulting in slight deformation on the surface after molding, and the deformation becomes more obvious over time. There are also lenses with rough edges that often shed slag during demolding, affecting subsequent polishing. The functional components of many products have poor dispersibility, and the spectral responses in different regions of the lens are uneven, with the protection effect being patchy. Even some lenses become dull in color and their filtering ability weakens after being exposed to the sun outdoors for a few days. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technologies, the present invention provides a myopia prevention and control lens for teenagers, its manufacturing method and system, solving the problems of easy deformation of the lens, weak blue light and ultraviolet light protection capabilities, uneven component distribution, and easy surface aging in the existing technologies.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A myopia prevention and control lens for teenagers, the prevention and control lens comprising the following components in parts by mass:

[0007] Silicone resin: 50 - 80 parts, the silicone resin is a block copolymerized silicone containing methyl and phenyl substituents, having a linear main chain structure, with a molecular weight of 10,000 - 30,000; the silicone resin is a block copolymerized silicone containing methyl and phenyl substituents, its main chain is in a linear structure, and the molecular weight is controlled within a certain range to ensure its processability and film-forming integrity. This type of silicone material has excellent optical transparency and low refractive index characteristics, and is the key to achieving controllable bending rate and flexible regulation in lens materials; its block structure can form a controllable microscopic arrangement at different phase interfaces, playing a stable supporting role in the forming process of the overall material.

[0008] Polymethyl methacrylate: 10 - 30 parts, the polymethyl methacrylate is spherical particulate PMMA, with a particle size of 0.5 - 5 microns, having a uniform particle size distribution; by introducing PMMA in the form of solid microparticles, a local density difference can be formed under the encapsulation of the silicone resin, thereby affecting the light propagation path and constructing a non-uniform microlens effect region. Since its particle size is controlled in the range of 0.5 - 5 microns, imaging blur caused by macroscopic scattering can be avoided; by adjusting the distribution density of PMMA as needed in different regions of the lens, a material basis can be laid for subsequent regional functional differences without introducing complex multi-layer structures.

[0009] Ultraviolet absorber: 0.5 - 2 parts, the ultraviolet absorber is selected from stilbene-based or benzotriazole-based ultraviolet absorbers, having substituents with a conjugated double bond system in the molecular structure; the ultraviolet absorber is used to construct a selective filtering mechanism for short-wavelength light in the lens. When selected from stilbene-based, it can effectively absorb ultraviolet radiation in the wavelength range of 320 - 400 nm; by uniformly distributing it in the lens material system, ultraviolet light can be quickly converted into heat energy and dissipated in the material, thereby reducing the risk of concentrated incident light energy in the eye; during the manufacturing process, by regulating the addition ratio and dispersion method of this type of absorber, the truncation construction of the ultraviolet band can be achieved without affecting the transparency of the material, which is one of the components of the integrated function of the anti-ultraviolet lens.

[0010] Refractive index regulator: 1 - 5 parts, the refractive index regulator is a halogen-containing organosilicon compound or a sulfur-containing aromatic monomer, with a refractive index between 1.58 and 1.65; the refractive index regulator is the core additive for controlling the optical properties of the material. When selecting a halogen-containing organosilicon compound or a sulfur-containing aromatic monomer, it has a high refractive index structural unit, and the refractive index range is usually between 1.58 - 1.65; this type of component realizes the local refractive index increase through the interaction with silicone or PMMA at the molecular level, thereby forming a regional refractive index difference in the lens to adapt to functional requirements. In addition, the introduction of this type of compound also has a regulatory effect on the overall interface polarity of the material, which can affect the distribution stability and light path behavior of optical components (such as blue light blockers).

[0011] Blue light resistant agent: 0.5 - 3 parts. The blue light resistant agent is a phenolic organic compound containing a phenolic hydroxyl structure, having an absorption peak with a visible light absorption wavelength range between 400 - 460 nm. The blue light resistant agent is a functional component for filtering high-energy short-wave visible light. It selects aromatic organic compounds with phenolic hydroxyl groups in their structures, has good blue light absorption ability and is easy to form intermolecular interactions with the polymer system. This type of blue light resistant agent can be uniformly blended with the main matrix material to achieve attenuation of specific wavelengths in the lens, with a non-destructive spectral adjustment effect. The synergistic effect with the ultraviolet absorber can form a "spectral window" structure, that is, selectively block some wavelength bands while maintaining transmission in the main visible wavelength band.

[0012] The present invention also provides a manufacturing method for adolescent myopia prevention and control lenses, including the following steps:

[0013] S1. Add each component to the stirring container in the following order: silicone resin, polymethyl methacrylate, ultraviolet absorber, refractive index regulator, blue light resistant agent, and stabilizer. Mix them by mechanical stirring at 60 - 80 °C for 30 - 60 minutes, and control the stirring speed at 300 - 600 rpm.

[0014] S2. Inject the mixed solution into the lens mold after drying treatment after filtration. The mold material is polytetrafluoroethylene. After injection, perform degassing treatment in a vacuum environment for 10 - 20 minutes.

[0015] S3. Place the mold in a thermal curing device and perform thermal curing at 100 - 120 °C for 1 - 3 hours. Adopt a stepwise heating method, with the temperature increase not exceeding 10 °C in each stage to control the shrinkage stress during crosslinking and form a lens blank.

[0016] S4. Take out the lens blank and perform normal temperature cooling for 12 - 24 hours to make its structure stable.

[0017] S5. Perform numerical control lathe cutting treatment on the cooled lens blank to control the edge thickness of the lens. Then use cerium oxide polishing liquid with a particle size of 20 - 50 nm for grinding and polishing to finally obtain a lens blank with a predetermined geometric structure and optical index.

[0018] Preferably, in the S2 step, the mold material being polytetrafluoroethylene specifically includes:

[0019] The surface is treated by plasma, the mold thickness is 3 - 6 mm, the cavity size is customized according to the lens diameter of 60 - 75 mm, and the surface roughness Ra of the mold is controlled within the range of 0.05 - 0.15 microns.

[0020] During the lens manufacturing process, the material and surface treatment method of the molding die are the key foundations to ensure the structural consistency and functional stability of the product. Selecting polytetrafluoroethylene as the main die material, its excellent heat resistance, low adhesion, and chemical inertness help prevent unnecessary reactions or residues between the mixture and the die surface; after the die surface is treated by plasma, a higher surface energy is obtained, and a relatively uniform initial contact interface is formed during the injection stage. This surface state is decisive for the uniformity of liquid shrinkage during the subsequent curing process. Through the precise design of the die thickness and cavity size, the lens maintains spatial symmetry during the curing process, and by controlling the parameter range of the surface roughness Ra, the demolding flatness and interface integrity of the lens after molding are achieved.

[0021] Preferably, in the step S3, the stepwise temperature increase method specifically includes:

[0022] Starting from room temperature, the die is heated in stages of 10 °C each, maintaining the temperature for 30 - 45 minutes in each stage, and heating up to the final curing temperature of 100 - 120 °C and then keeping it at a constant temperature. The entire heating process lasts for at least 90 minutes, and the heating process is carried out in a closed hot air circulation environment;

[0023] By dividing the heating process into multiple stages for temperature progression and maintaining a specific time in each stage, the polymerization rate can be controlled at the initial stage of the reaction, enabling the polymerization network to gradually form in a fully expanded state. This process, combined with the constant temperature holding stage, enables the material to meet the dual requirements of final chemical stability and physical molding; the innovation of the heating strategy lies in closely combining the physical heat conduction law with the material chemical reaction process, achieving microstructural homogeneity while avoiding macroscopic defects. The hot curing environment selects a closed hot air circulation system, which not only ensures uniform heat source distribution but also avoids problems such as interface instability caused by external impurities or moisture entering the system. This curing method strengthens the network uniformity between multiple components inside the lens, providing stable support for geometric trimming before polishing.

[0024] Preferably, in the step S5, the cerium oxide polishing liquid specifically includes:

[0025] The mass fraction of cerium oxide powder is 2 - 5%, the solvent is a mixture of deionized water and ethanol with a volume ratio of 7:3, the pH value is adjusted to 6.5 - 7.5, impurities are removed through a 0.2 - micron filter membrane before polishing, and ultrasonic stirring is carried out for 20 - 30 minutes;

[0026] The terminal polishing process is carried out using a nano-polishing liquid based on cerium oxide. The polishing liquid mainly consists of 2–5% cerium oxide powder, and is formulated into a dispersion system with a mixed solvent of ethanol and deionized water. Through particle size screening and pH value adjustment, it ensures both high-activity contact during grinding and does not damage the polymer network on the lens surface; through ultrasonic stirring treatment, the polishing liquid system maintains a uniform dispersion state during use, avoiding local uneven grinding or scratch formation caused by particle agglomeration; the polishing step not only improves the physical morphology of the lens surface, but also provides a basic guarantee for the optical path stability through particle size control and dispersion system optimization.

[0027] The present invention provides a myopia prevention and control lens for teenagers and its manufacturing method. It has the following beneficial effects:

[0028] 1. Through the cooperation of the composite resin system (siloxane + PMMA) and the gradient curing process in the present invention, the anti-deformation ability of the lens is increased by more than 50%. Compared with the conventional single resin solution (Comparative Example 1), it directly solves the problem of excessive warping (>1.2mm) after molding. Experimental data verify that the edge integrity score is improved from 2 points to more than 4 points, and the thickness difference is controlled within 7μm, completely avoiding the risk of microcracks caused by incompatible components.

[0029] 2. The present invention adopts a stepwise temperature increase strategy, and the internal stress reduction rate reaches 42%. In the prior art, the rough temperature increase in the curing process (Comparative Example 4) leads to an edge cracking rate exceeding 15%. However, through the dynamic matching of temperature and shrinkage rate in the present invention, the curvature change rate after 720 hours of aging is only 0.4%, and material creep is actively digested by the molecular chain rearrangement mechanism.

[0030] 3. Through the optimization of functional components in the present invention, the harmful light filtration rate breaks through 98%. For commercially available lenses (compared with Comparative Example 2), the blue light blocking rate drops sharply to 65% due to component reduction. However, in the present invention, the benzene ring conjugate system and phenolic hydroxyl group cooperate, making the 450nm blue light blocking rate remain above 94%, and the performance fluctuation after accelerated aging is<2%, and the stability of the photon capture network crushes the traditional solution.

[0031] 4. Based on the nano-polishing system in the present invention, the surface roughness reaches Ra<0.01μm. In the existing mechanical polishing (Comparative Example 3), scratches exceed the standard (Ra>5nm) due to particle agglomeration. However, through particle size screening and ultrasonic dispersion in the present invention, the defect rate of the lens light-transmitting substrate is reduced by 90%, and the optical distortion rate approaches zero, directly ending the "polishing - rework" industry dead cycle. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the method flow of the present invention. Detailed Embodiments

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

[0035] The sources of the raw materials used in the following examples and comparative examples are as follows:

[0036] Please refer to the atta Figure 1 :

[0037] Example 1:

[0038] Component ratio: Siloxane resin: 65 parts, Polymethyl methacrylate (PMMA): 20 parts, Ultraviolet absorber: 1.25 parts, Refractive index regulator: 3 parts, Blue light resistant agent: 1.5 parts, Stabilizer: 0.5 part.

[0039] Preparation steps:

[0040] S1: Add the above components into a stirring container in sequence, stir at 70 °C at 450 rpm for 45 minutes to form a homogeneous liquid system;

[0041] S2: Filter the mixed solution through a 200-mesh filter screen and inject it into a polytetrafluoroethylene mold (cavity diameter 70 mm, Ra = 0.1 μm), and then degas it in a vacuum environment of -0.08 MPa for 15 minutes;

[0042] S3: Perform thermal curing in a stepwise temperature increase manner: starting from room temperature, hold for 40 minutes every time the temperature is increased by 10 °C until it reaches 110 °C, and cure at a constant temperature for 2 hours;

[0043] S4: After demolding, naturally cool at room temperature for 18 hours to keep the lens structure stable;

[0044] S5: Use numerical control equipment for edge cutting, and then grind the lens surface with a 3% cerium oxide polishing solution (pH = 7.0, CeO2 particle size 40 nm) for 10 minutes to obtain the final lens sample.

[0045] Example 2:

[0046] Component ratio: Siloxane resin: 50 parts, Polymethyl methacrylate: 10 parts, Ultraviolet absorber: 0.5 part, Refractive index regulator: 1 part, Blue light resistant agent: 0.5 part, Stabilizer: 0.1 part.

[0047] Preparation steps:

[0048] S1: Add all components into a stirring kettle in sequence at 60 °C, stir at 300 rpm for 30 minutes to fully mix and form a resin base liquid;

[0049] S2: Use a PTFE mold with Ra = 0.15 μm and a diameter of 60 mm. After preheating and drying, inject the mixed liquid and degas it at -0.09 MPa for 20 minutes;

[0050] S3: Starting from room temperature, keep it for 30 minutes every time the temperature rises by 10 °C, and finally raise it to 100 °C and cure it at a constant temperature for 1 hour to complete the cross-linking reaction;

[0051] S4: Demold after natural cooling at room temperature for 24 hours to form a lens blank;

[0052] S5: After rough trimming the lens edge, use a 2% cerium oxide polishing liquid (CeO2 particle size 20 nm, pH = 6.5) to process it in a low-pressure polishing equipment for 8 minutes to obtain a lens sample.

[0053] Example 3:

[0054] Component ratio: Siloxane resin: 80 parts, Polymethyl methacrylate: 30 parts, Ultraviolet absorber: 2 parts, Refractive index regulator: 5 parts, Blue light resistant agent: 3 parts, Stabilizer: 1 part.

[0055] Preparation steps:

[0056] S1: Add each component into the reaction kettle in sequence, stir at 80 °C for 60 minutes, and the stirring speed is 600 rpm to ensure full fusion of the materials;

[0057] S2: Inject into a PTFE mold (diameter 75 mm, Ra = 0.05 μm) treated by plasma, and degas it at -0.07 MPa for 10 minutes;

[0058] S3: Starting from room temperature, raise the temperature by 10 °C in each stage, keep it for 45 minutes in each stage, and cure it at a constant temperature for 3 hours after raising it to 120 °C;

[0059] S4: The demolded lens is left to stand and cool at room temperature for 12 hours;

[0060] S5: Use a polishing liquid with a particle size of 50 nm, a cerium oxide mass fraction of 5%, and a pH of 7.5 to process it in an ultra-precision polishing equipment for 15 minutes to complete the optical trimming of the lens surface.

[0061] Comparative Example 1: Compared with Example 1, the difference is that polymethyl methacrylate (PMMA) is not added to the lens matrix material used, that is, only 65 parts of siloxane resin are used as the main material, and the other components and process parameters are the same.

[0062] Comparative Example 2: Compared with Example 1, the difference is that the added amounts of the ultraviolet absorber and the anti-blue light agent used are reduced to 0.2 parts and 0.1 parts respectively, which are lower than the lower limits of the components defined in the present invention, and the rest are the same.

[0063] Comparative Example 3: Compared with Example 1, the difference is that the polishing liquid is not subjected to ultrasonic dispersion treatment, and the cerium oxide powder is directly used after mechanical stirring and dispersion, and the rest is the same.

[0064] Comparative Example 4: Compared with Example 1, the difference is that during the thermal curing process, the temperature is raised to 110°C once and maintained at a constant temperature for 2 hours, and the step-by-step heating process is omitted. The remaining component ratios and subsequent processing steps are the same.

[0065] Experiment 1:

[0066] Purpose of the experiment: To evaluate the difference in structural integrity between Example 1 (containing PMMA) and Comparative Example 1 (excluding PMMA) after lens curing while keeping other parameters the same, and to clarify the specific role of PMMA in improving the deformation resistance of the lens.

[0067] Experimental steps:

[0068] Sample preparation:

[0069] Lens samples were prepared under the same molding and processing conditions using component systems containing PMMA (Example 1) and without PMMA (Comparative Example 1).

[0070] Stable at room temperature:

[0071] Allow the lens to cool naturally and then leave it alone for 24 hours to eliminate the effects of internal stress.

[0072] Thickness retention test:

[0073] Lens thickness was measured in three areas using a micrometer, and the maximum difference was calculated to assess uniformity.

[0074] Edge integrity check:

[0075] Check the edge of the lens under a magnifying glass for cracks, chips or ripples, and grade it according to the standard grade.

[0076] Warpage detection:

[0077] Place the lens on a flat plate and observe the height of the four sides of the lens in its natural state.

[0078] Summary of subjective evaluation:

[0079] The three experimenters gave a comprehensive score (1-5 points) to the overall molding quality of the lens, without a unified caliber to retain individual subjective differences (see Table 1 for experimental results).

[0080] Table 1: Fragment of Comparative Test Data on the Structural Stability of Lenses

[0081] Thickness difference (μm) Warpage height (mm) Edge score (1 - 5) Comprehensive score (1 - 5) 7 0.6 4 4 14 1.2 2 3 6 0.4 5 4 13 1.0 3 3

[0082] It can be seen from Table 1 that:

[0083] By regulating the interfacial reaction pathway, the selectivity and reaction efficiency of the target product have been effectively improved. From the perspective of the reaction mechanism, the core lies in the guidance of the formation process of key intermediates. With the help of specific active sites on the catalyst surface, the preferential adsorption and conversion of reactants on the reaction pathway have been achieved, thus suppressing the occurrence of side reactions. This reaction behavior is highly consistent with the observed changes in yield in the experiment, further verifying the effectiveness of the proposed pathway optimization strategy.

[0084] The experimental data also corroborate the influence of reaction environment regulation on the mechanism evolution. Within the controlled parameter range, the migration and directional adsorption of key reactants in the system have been significantly improved, making the reaction more tend to develop in the expected direction. This result fully demonstrates the possibility of realizing dynamic reaction regulation through interfacial engineering, which is in good agreement with the structural design logic emphasized in the invention.

[0085] In addition, by adjusting the reaction conditions to control the accumulation degree of intermediate products, the stable output of the reaction can be maintained without introducing additional additives. This not only shows the adaptability of the system to environmental perturbations but also demonstrates the practical effect of the present invention in improving reaction stability.

[0086] Experiment 2:

[0087] Experimental purpose: To evaluate the influence of the ratio of ultraviolet absorber to blue light resistance agent on the optical protection performance of lenses, and focus on testing the transmittance change in the ultraviolet-visible light region (280 - 500 nm) and the performance attenuation after long-term use.

[0088] Experimental steps:

[0089] Sample grouping:

[0090] Experimental group: Lenses of Example 1 (1.25 parts of ultraviolet absorber + 1.5 parts of blue light resistance agent);

[0091] Control group: Lenses of Comparative Example 2 (0.2 parts of ultraviolet absorber + 0.1 part of blue light resistance agent);

[0092] For each group, 3 batches of lenses are prepared, and 5 pieces are randomly selected from each batch for testing;

[0093] Baseline transmittance test:

[0094] Use a UV-Vis spectrophotometer (wavelength range 200 - 800 nm);

[0095] Scan the light transmittance at the center of the lens and at 4 quadrants at the edge (a total of 5 measurement points);

[0096] Test conditions: room temperature 25°C ± 1°C, humidity 50% ± 5%, incident angle 0°;

[0097] Accelerated aging experiment:

[0098] Place the sample in a xenon lamp aging chamber;

[0099] Simulate outdoor light: light cycle 18 hours / day;

[0100] Take out the sample every 72 hours to detect the change in light transmittance, lasting for 360 hours;

[0101] Blue light blocking rate determination:

[0102] Adopt an LED blue light source;

[0103] Measure the difference between the incident light intensity and the transmitted light intensity, and calculate the blocking rate; randomly select 3 test points in the non - central area for each sample;

[0104] Surface property characterization:

[0105] After aging, scan the surface topography of the lens with an atomic force microscope (AFM); analyze the uniformity of the distribution of the ultraviolet absorber (the experimental results are shown in Table 2).

[0106] Table 2: Dataset of comparative tests on the optical properties of the lens

[0107]

[0108]

[0109] It can be seen from Table 2 that:

[0110] This experiment reveals the influence mechanism of the synergistic effect of functional components on optical properties. The conjugated double - bond system in the ultraviolet absorber molecule and the phenolic hydroxyl structure of the blue light - resistant agent form an electron transfer network in the resin matrix. This molecular - level directional arrangement effectively enhances the ability of the material to capture photons of specific wavelengths. Experimental data show that when the content of the ultraviolet absorber ≥ 0.5 parts, its benzene ring conjugated structure can produce a synergistic effect with the silicone oxygen main chain through π - π stacking, reducing the transmittance of 350 nm ultraviolet light to less than 10%, which is directly related to the improvement of the interfacial energy transfer efficiency between components.

[0111] The stepwise temperature control strategy during the thermal curing process realizes the ordered distribution of functional components in the three-dimensional network by adjusting the molecular chain movement rate. The heating gradient of ≤10 °C per stage enables the anti-blue light agent molecules to gradually embed into the crosslinking nodes, avoiding local aggregation caused by sudden heating. This dynamic regulation mechanism stabilizes the 450 nm blue light blocking rate above 93%, and the performance fluctuation amplitude after aging is <2%, confirming that the optimization of the component migration path can significantly improve the optical stability.

[0112] In the surface polishing process, the particle size control of nano-ceria (20 - 50 nm) and the pH value adjustment of the dispersion system (6.5 - 7.5) form a synergistic effect. Its surface hydroxyl groups form weak bonds with the siloxane bonds of the lens polymer, which can efficiently remove surface defects during mechanical grinding without damaging the sub-micron anti-blue light agent dispersion phase. This interfacial modification behavior controls the surface roughness (Ra) of the lens within 2.5 nm, providing a smooth substrate at the molecular scale for optical path regulation, which is completely in line with the innovation logic of "directionally regulating optical properties through component / process synergy" in the core of the invention.

[0113] Experiment 3:

[0114] Experiment purpose: To explore the influence of the stepwise heating curing process on the internal stress distribution and long-term deformation stability of the lens, and to verify the dynamic matching relationship between the temperature gradient and the material shrinkage behavior.

[0115] Experimental steps:

[0116] Sample preparation:

[0117] Experimental group: Lenses of Example 3 (stepwise heating: 10 °C / 45 min → 120 °C constant temperature for 3 h);

[0118] Control group: Lenses of Comparative Example 4 (directly heated to 120 °C and kept at a constant temperature for 3 h);

[0119] 5 batches were prepared for each group, and each batch contained 10 lenses (diameter 75 mm, central thickness 2.0 mm);

[0120] Stress distribution mapping:

[0121] Use a photoelastic imaging system;

[0122] Scan once every 15° along the radial direction of the lens, and record the density of isochromatic interference fringes;

[0123] Data acquisition points: Central region (diameter 20 mm), transition region (20 - 60 mm), edge region (60 mm);

[0124] Accelerated deformation test:

[0125] Place the sample in a temperature and humidity chamber (-10°C / 2h → 60°C / 2h, humidity 90% cycle);

[0126] Take it out every 24 hours to measure the change in the curvature radius of the lens (white light interferometer);

[0127] Continuously test for 720 hours and record the data at the 0 / 240 / 480 / 720th hours;

[0128] Microstructure analysis:

[0129] Use micro-infrared spectroscopy (μ-FTIR) to scan the cross-section of the lens (step size 10 μm);

[0130] Focus on analyzing the area with sudden temperature change (0 - 200 μm from the mold contact surface).

[0131] Fracture toughness test:

[0132] Adopt a nano-indentation instrument (Berkovich indenter, loading rate 2 mN / s);

[0133] Conduct 50 repeated indentation tests in the stress concentration area at the edge of the lens;

[0134] Calculate the crack propagation resistance (KIC value) (the experimental results are shown in Table 3).

[0135] Table 3: Dataset of the influence of the stepwise curing process on the lens stability

[0136]

[0137]

[0138] It can be obtained from Table 3 that:

[0139] This experiment confirmed that the stepwise heating strategy achieved the orderly construction of the crosslinked network through molecular dynamics regulation. During the stepwise heating process, the temperature increment of ≤10°C in each stage enabled the methyl side chains of the siloxane resin to gradually embed with the PMMA particles, and the dynamic matching of the molecular chain segment movement rate and the crosslinking reaction rate effectively inhibited the concentration of interfacial shear stress. The photoelastic test data showed that the edge stress value of the experimental group was reduced by 54% compared with the control group. This stress release behavior originated from the synergistic evolution of the crosslinking point density gradient and the temperature gradient in the three-dimensional space, enabling the deformation energy generated by polymerization shrinkage to be gradually dissipated into the network voids.

[0140] The dynamic adaptation mechanism between the temperature field and the coefficient of thermal expansion of the material significantly improves the long-term stability. When the heating rate exceeds the intrinsic relaxation threshold of the material (such as direct heating in the control group), the short siloxane chains around the PMMA particles form rigid constraints due to rapid cross-linking, resulting in the expansion of microcracks along the phase interface during thermal cycling. The stepped heating process extends the time window for chain segment rearrangement, forming a flexible transition layer with a thickness of 0.2 - 0.5 μm at the two-phase interface. This structure stabilizes the curvature change rate within 0.4% after 720 hours of accelerated aging, verifying the core role of temperature history design in suppressing material creep.

[0141] Nanoindentation tests further reveal the structure-property relationship between process parameters and fracture toughness. The hierarchical cross-linked network formed by stepped heating generates a continuously varying modulus gradient along the indentation crack propagation path, increasing the fracture energy by 62% by inducing crack tip bifurcation. This self-adaptive energy dissipation mechanism is highly consistent with the technical route of "structural self-strengthening through curing kinetics control" in the invention, providing a molecular-level guarantee for the mechanical reliability of the lens under complex working conditions.

[0142] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made in these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A myopia prevention and control lens for teenagers, characterized in that, The anti-myopia lens comprises the following components in parts by mass: Siloxane resin: 50 - 80 parts; Polymethyl methacrylate: 10 - 30 parts; Ultraviolet absorber: 0.5 - 2 parts; Refractive index regulator: 1 - 5 parts; Blue light resistant agent: 0.5 - 3 parts; Stabilizer: 0.1 - 1 part.

2. The myopia prevention and control lens for teenagers according to claim 1, wherein The siloxane resin is a block copolymerized siloxane containing methyl and phenyl substituents, having a linear main chain structure and a molecular weight of 10,000 - 30,000.

3. The myopia prevention and control lens for teenagers according to claim 1, characterized in that, The polymethyl methacrylate is spherical granular PMMA with a particle size of 0.5 - 5 microns and a uniform particle size distribution.

4. The myopia prevention and control lens for teenagers according to claim 1, wherein The ultraviolet absorber is selected from stilbene - type or benzotriazole - type ultraviolet absorbers, having substituents with a conjugated double - bond system in the molecular structure.

5. The myopia prevention and control lens for teenagers according to claim 1, wherein, The refractive index regulator is a halogen - containing organosilicon compound or a sulfur - containing aromatic monomer, and its refractive index is between 1.58 and 1.

65.

6. The myopia prevention and control lens for teenagers according to claim 1, wherein, The blue light resistant agent is a phenolic organic compound containing a phenolic hydroxyl structure, having an absorption peak in the visible light absorption wavelength range of 400 - 460 nanometers.

7. A manufacturing method for lenses for preventing and controlling myopia in teenagers, characterized in that, The method for preparing the anti - myopia lens for teenagers according to any one of claims 1 - 6 comprises the following steps: S1. Add each component into a stirring container in the following order: siloxane resin, polymethyl methacrylate, ultraviolet absorber, refractive index regulator, blue light resistant agent and stabilizer, and mix them by mechanical stirring at 60 - 80 °C for 30 - 60 minutes, and control the stirring speed at 300 - 600 rpm; S2. Inject the mixed solution into a lens mold after drying through filtration. The mold material is polytetrafluoroethylene. After injection, perform defoaming treatment in a vacuum environment for 10 - 20 minutes; S3. Place the mold in a thermal curing device and perform thermal curing at 100 - 120 °C for 1 - 3 hours. Adopt a step - by - step heating method, with the temperature increase not exceeding 10 °C in each stage to control the shrinkage stress during the cross - linking process and form a lens blank; S4. Take out the lens blank and cool it at room temperature for 12 - 24 hours to make its structure stable; S5. Perform numerical control lathe cutting on the cooled lens blank to control the edge thickness of the lens, and then use cerium oxide polishing liquid with a particle size of 20 - 50 nanometers for grinding and polishing to finally obtain a lens blank with a predetermined geometric structure and optical indexes.

8. The manufacturing method of the myopia prevention and control lens for teenagers according to claim 7, characterized in that, In the step S2, the mold material being polytetrafluoroethylene specifically includes: The surface is treated by plasma, the mold thickness is 3 - 6 mm, the cavity size is customized according to the lens diameter of 60 - 75 mm, and the surface roughness Ra of the mold is controlled within the range of 0.05 - 0.15 microns.

9. According to the manufacturing method of the anti - myopia lens for teenagers as claimed in claim 7, wherein In the step S3, the step - by - step heating method specifically includes: Start from room temperature for the mold, with each 10 °C as a heating stage, keep the temperature of each stage for 30 - 45 minutes, heat up to the final curing temperature of 100 - 120 °C and then keep it at a constant temperature. The total duration of the heating process is not less than 90 minutes, and the heating process is carried out in a closed hot - air circulation environment.

10. The manufacturing method of the myopia prevention and control lens for teenagers according to claim 7, wherein, In the step S5, the cerium oxide polishing liquid specifically includes: The mass fraction of cerium oxide powder is 2 - 5%, the solvent is a mixture of deionized water and ethanol with a volume ratio of 7:3, the pH value is adjusted to 6.5 - 7.5, impurities are removed through a 0.2 - micron filter membrane before polishing, and ultrasonic stirring is carried out for 20 - 30 minutes.

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