A moisturizing anti-soil contact lens and method of making same

Abstract

The application provides a moisturizing anti-fouling contact lens and a preparation method thereof, and belongs to the technical field of contact lenses. The application adopts a silicon hydrogel as a substrate, and adopts sulfobetaine, carboxybetaine and polymethyl carboxybetaine to construct a gradient functional layer. Through semi-solidification pre-polymerization, low-temperature impregnation and two-stage photopolymerization, the functional layer is firmly combined with the substrate. The obtained product has high oxygen permeability, excellent moisturizing property and anti-protein contamination capacity, and has stable structure and comfortable wearing, and can effectively solve the problems of easy contamination, poor moisturizing property and easy falling of the functional layer of the traditional contact lens.

Description

Technical Field

[0001] This invention relates to the field of contact lens technology, and in particular to a moisturizing and stain-resistant contact lens and its preparation method. Background Technology

[0002] As a medical optical device that comes into direct contact with the eye, the oxygen permeability, biocompatibility, stain resistance, and wearing comfort of contact lenses are the core indicators determining product performance. With the increasing number of people with myopia and the upgrading of consumer demands, high oxygen permeability silicone hydrogel contact lenses have become the mainstream product in the market because they solve the problems of insufficient oxygen permeability and easy occurrence of eye hypoxia and dryness caused by traditional hydrogels.

[0003] However, existing high-oxygen-permeable silicone hydrogel contact lenses still have significant technical drawbacks: their base material contains siloxane segments, resulting in a highly hydrophobic surface that easily attracts proteins, lipids, and other substances from tears during wear, forming deposits. These deposits not only reduce lens transmittance and affect visual quality but also irritate the ocular surface, causing discomfort such as dryness, foreign body sensation, and inflammation. In severe cases, they can even prevent long-term use, limiting the user experience of silicone hydrogel contact lenses.

[0004] To address the aforementioned antifouling challenges, the industry has extensively researched the application of zwitterionic materials. Among them, sulfobetaine methacrylate (SBMA), carboxybetaine methacrylate (CBMA), and polymethyl methacrylate carboxybetaine (PCBMA) have demonstrated excellent antifouling properties. These zwitterionic materials contain isotropic cation-anion pairs in their molecular structure, enabling them to form a dense hydration layer on the material surface. Through steric hindrance and charge repulsion, they effectively prevent the adsorption of pollutants such as proteins and lipids, while also exhibiting good biocompatibility and being non-irritating to the ocular surface.

[0005] However, SBMA, CBMA, and PCBMA all have high charge density and strong hydrophilicity. If they are used directly as the main material to prepare contact lenses, it will result in insufficient mechanical strength, excessive swelling rate, poor dimensional stability, and a significant decrease in oxygen permeability, which cannot meet the clinical wearing requirements of contact lenses. If they are simply coated on the surface of silicone hydrogel, there are defects such as poor adhesion between the coating and the substrate, easy peeling, and poor durability of anti-fouling performance, which make it difficult to achieve industrial production and long-term clinical application.

[0006] Therefore, how to balance the high oxygen permeability and high mechanical properties of silicone hydrogels with the strong antifouling and high biocompatibility of zwitterionic materials, and solve the technical problems such as structural stability and interlayer bonding force in the process of combining the two, so as to develop a contact lens with high oxygen permeability, excellent antifouling effect, dimensional stability and comfortable wear, has become a key technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a moisturizing and stain-resistant contact lens and its preparation method, in order to solve the above-mentioned technical problems.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a moisturizing and stain-resistant contact lens, comprising a silicone hydrogel base and a gradient betaine functional layer; The silicone hydrogel substrate is prepared from the following raw materials in parts by weight: 35-45 parts of tris(trimethylsiloxy)propyl methacrylate, 15-25 parts of siloxane methacrylate, 12-18 parts of N,N-dimethylacrylamide, 1-2 parts of methacrylic acid, 0.4-0.6 parts of ethylene glycol dimethacrylate, 0.5-0.8 parts of photoinitiator, and 15-22 parts of diluent; The gradient betaine functional layer is prepared by a mixture of functional monomers, which consists of the following raw materials in parts by mass: 30-40 parts of sulfobetaine methacrylate, 20-30 parts of carboxybetaine methacrylate, 30-40 parts of polymethyl methacrylate carboxybetaine, 0.4-0.6 parts of photoinitiator 2, and 0.2-3 parts of ethanol solution.

[0009] Furthermore, photoinitiator 1 and photoinitiator 2 are independently Irgacure 1173 or Irgacure 2959; The diluent includes tert-butanol or ethylene glycol.

[0010] Furthermore, the number-average molecular weight of the polymethacrylic acid carboxybetaine is 3000~6000 g / mol; In the ethanol solution, the volume ratio of water to ethanol is 7~9:1~3.

[0011] The present invention also provides a method for preparing the above-mentioned moisturizing and stain-resistant contact lenses, comprising the following steps: Step 1) Mix tris(trimethylsiloxy)propyl methacrylate, siloxane methacrylate, N,N-dimethylacrylamide, methacrylic acid, ethylene glycol dimethacrylate, photoinitiator 1 and diluent, then inject the mixture into a mold for prepolymerization, and obtain a semi-cured silicone hydrogel substrate after demolding. Step 2) Mix polymethyl methacrylate carboxy betaine and ethanol solution, stir, hydrate and stand in sequence, then add sulfobetaine methacrylate and carboxybetaine methacrylate in sequence until fully mixed, finally add photoinitiator 2, and degas under vacuum to obtain functional monomer mixture. Step 3) Under light-protected conditions, immerse the semi-cured silicone hydrogel substrate in a mixture of functional monomers, remove it, and carry out a polymerization reaction. After post-treatment, you will get contact lenses with moisturizing and anti-fouling effects.

[0012] Furthermore, in step 1), the prepolymerization is photopolymerization, and the prepolymerization is carried out in an inert atmosphere.

[0013] Furthermore, in step 2), the hydration temperature is 22~34℃, and the settling time is 8~14h.

[0014] Furthermore, in step 3), the semi-cured silicone hydrogel substrate is immersed in a functional monomer mixture at a temperature of 2~5℃ for 15~35 minutes.

[0015] Furthermore, in step 3), the polymerization reaction is a two-stage polymerization, and the light intensity of the first stage polymerization is 1~2 mW / cm². 2 The time is 1-2 minutes, and the light intensity for the second polymerization stage is 5-8 mW / cm². 2 The time is 5-10 minutes.

[0016] Furthermore, in step 3), the post-processing includes sequential multi-stage extraction, hydration treatment, stabilization treatment, and sterilization treatment.

[0017] Furthermore, the extractant for the multi-stage extraction includes one or more of ethanol, aqueous ethanol solution, and deionized water; The hydration treatment was performed in PBS buffer for 24-36 hours. The stabilization treatment was carried out in a 0.9 wt% sodium chloride solution for 48–60 h.

[0018] The beneficial effects of this invention are: This invention achieves highly efficient synergy between a silica hydrogel substrate and three zwitterionic materials—sulfobetaine methacrylate, carboxybetaine methacrylate, and polymethacrylate carboxybetaine—by constructing a gradient interpenetrating polymer network structure. Compared to existing technologies, this invention offers the following significant advantages: Firstly, the anti-fouling performance is significantly improved and remains stable over time. This invention uses high charge density polymethyl methacrylate carboxybetaine (PCBMA) and sulfobetaine methacrylate (SBMA) as the core of anti-fouling, while carboxybetaine methacrylate (CBMA) assists in anti-fouling and provides an anchoring effect. Through gradient penetration and in-situ polymerization, a dense zwitterionic functional layer is formed in a 5-10 μm area on the lens surface. Relying on the strong hydration layer formed by the synergy of the three, it can effectively repel pollutants such as proteins and lipids, reducing protein adsorption by more than 90% compared to ordinary silicone hydrogel lenses. Moreover, the functional layer and the substrate are firmly bonded through covalent grafting and physical entanglement, and the anti-fouling performance does not significantly decrease after repeated washing.

[0019] Secondly, it balances high oxygen permeability with dimensional stability. This invention adopts a gradient design of "substrate load-bearing and surface function". The internal silicone hydrogel substrate retains high oxygen permeability to ensure oxygen supply to the eye; the surface functional layer is limited to the surface, avoiding excessive swelling and dimensional drift of the lens caused by the high charge of zwitterionic materials, and meeting the requirements for clinical wearing accuracy.

[0020] Thirdly, it offers high wearing comfort and good biocompatibility. CBMA in the functional layer can buffer changes in tear pH and reduce irritation to the ocular surface. The strong hydrophilicity of PCBMA and SBMA makes the lens surface superhydrophilic, reducing the coefficient of friction and effectively relieving dryness and foreign body sensation. Moreover, all materials have good biocompatibility, no cytotoxicity, and are suitable for long-term wear.

[0021] Furthermore, this invention does not require the addition of additional crosslinking agents, the process is simple and can be mass-produced industrially, which reduces production costs and avoids safety hazards caused by crosslinking agent residue. Detailed Implementation

[0022] This invention provides a moisturizing and stain-resistant contact lens, comprising a silicone hydrogel base and a gradient betaine functional layer; The silicone hydrogel substrate is prepared from the following raw materials in parts by weight: 35-45 parts of tris(trimethylsiloxy)propyl methacrylate, 15-25 parts of siloxane methacrylate, 12-18 parts of N,N-dimethylacrylamide, 1-2 parts of methacrylic acid, 0.4-0.6 parts of ethylene glycol dimethacrylate, 0.5-0.8 parts of photoinitiator, and 15-22 parts of diluent; The gradient betaine functional layer is prepared by a mixture of functional monomers, which consists of the following raw materials in parts by mass: 30-40 parts of sulfobetaine methacrylate, 20-30 parts of carboxybetaine methacrylate, 30-40 parts of polymethyl methacrylate carboxybetaine, 0.4-0.6 parts of photoinitiator 2, and 0.2-3 parts of ethanol solution.

[0023] In this invention, the amount of tris(trimethylsiloxy)propyl methacrylate added is preferably 38 to 42 parts by weight. In this invention, the amount of siloxane methacrylate added is preferably 18 to 22 parts by weight. In this invention, the amount of N,N-dimethylacrylamide added is preferably 15 parts by weight. In this invention, the amount of methacrylic acid added is preferably 1.5 parts by weight. In this invention, the amount of ethylene glycol dimethacrylate added is preferably 0.5 parts by weight. In this invention, the amount of photoinitiator 1 added is preferably 0.7 parts by weight. In this invention, the amount of the diluent added is preferably 17 to 20 parts by weight.

[0024] In this invention, by controlling the amount of raw materials added, the degree of crosslinking of the silicone hydrogel substrate is kept at a low level, so as to leave free volume for the subsequent penetration of the functional monomer mixture while ensuring mechanical strength.

[0025] In this invention, the amount of sulfobetaine methacrylate added is preferably 32 to 38 parts by weight, and more preferably 35 parts; In this invention, the amount of carboxybetaine methacrylate added is preferably 22 to 28 parts by weight, and more preferably 25 parts; In this invention, the amount of polymethacrylic acid carboxybetaine added is preferably 32 to 38 parts by weight, and more preferably 35 parts.

[0026] In this invention, the amount of photoinitiator 2 added is preferably 0.5 parts by weight.

[0027] In this invention, photoinitiator 1 and photoinitiator 2 are independently Irgacure 1173 or Irgacure 2959; The diluent includes tert-butanol or ethylene glycol, preferably tert-butanol.

[0028] In this invention, the number average molecular weight of the polymethacrylic acid carboxybetaine is 3000~6000 g / mol, preferably 3500~5500 g / mol; In the ethanol solution, the volume ratio of water to ethanol is 7~9:1~3, preferably 8:2.

[0029] The present invention also provides a method for preparing the above-mentioned moisturizing and stain-resistant contact lenses, comprising the following steps: Step 1) Mix tris(trimethylsiloxy)propyl methacrylate, siloxane methacrylate, N,N-dimethylacrylamide, methacrylic acid, ethylene glycol dimethacrylate, photoinitiator 1 and diluent, then inject the mixture into a mold for prepolymerization, and obtain a semi-cured silicone hydrogel substrate after demolding. Step 2) Mix polymethyl methacrylate carboxy betaine and ethanol solution, stir, hydrate and stand in sequence, then add sulfobetaine methacrylate and carboxybetaine methacrylate in sequence until fully mixed, finally add photoinitiator 2, and degas under vacuum to obtain functional monomer mixture. Step 3) Under light-protected conditions, immerse the semi-cured silicone hydrogel substrate in a mixture of functional monomers, remove it, and carry out a polymerization reaction. After post-treatment, you will get contact lenses with moisturizing and anti-fouling effects.

[0030] In this invention, in step 1), the prepolymerization is photopolymerization, and the prepolymerization is carried out in an inert atmosphere.

[0031] In this invention, in step 2), the hydration temperature is 22~34℃, preferably 25~30℃; the settling time is 8~14h, preferably 10~12h.

[0032] In this invention, in step 3), the semi-cured silicone hydrogel substrate is immersed in a functional monomer mixture at a temperature of 2-5°C, preferably 3-4°C, for a time of 15-35 min, preferably 20 min.

[0033] In this invention, in step 3), the polymerization reaction is a two-stage polymerization, and the light intensity of the first stage polymerization is preferably 1~2 mW / cm². 2 The optimal time is 1-2 minutes; The light intensity for the second polymerization stage is 5~8 mW / cm². 2 The preferred value is 6~7 mW / cm 2 The optimal time is 5-10 minutes.

[0034] In this invention, a two-stage photopolymerization process is adopted. Low-intensity prepolymerization reduces internal stress and avoids phase separation, while high-intensity curing ensures complete polymerization. At the same time, it achieves a firm grafting of the functional layer and the substrate, ensuring the optical and structural stability of the lens.

[0035] In this invention, step 3) includes sequential multi-stage extraction, hydration treatment, stabilization treatment and sterilization treatment.

[0036] In this invention, the extractant for the multi-stage extraction includes one or more of ethanol, aqueous ethanol solution and deionized water, preferably ethanol, aqueous ethanol solution and deionized water are used sequentially for extraction.

[0037] In this invention, multi-stage extraction with gradient replacement can effectively avoid network collapse caused by sudden solvent changes.

[0038] In this invention, the hydration treatment is performed in PBS buffer for 24-36 hours, preferably 30 hours.

[0039] In this invention, hydration treatment ensures that the betaine chains are fully extended, forming a stable hydration layer.

[0040] In this invention, the stabilization treatment is carried out in a sodium chloride solution with a concentration of 0.9 wt%; the stabilization time is 48-60 h, preferably 50-55 h.

[0041] In this invention, the purpose of the stabilization process is to neutralize the charge.

[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] 38 parts of tris(trimethylsiloxy)propyl methacrylate, 18 parts of siloxane methacrylate, 15 parts of N,N-dimethylacrylamide, 1.5 parts of methacrylic acid, 0.5 parts of ethylene glycol dimethacrylate, 0.7 parts of Irgacure 1173 and 17.3 parts of tert-butanol were placed in a beaker, mixed evenly, and then injected into a contact lens mold. The mold was placed under a nitrogen atmosphere for photopolymerization prepolymerization. After prepolymerization was completed, the mold was demolded to obtain a semi-cured silicone hydrogel substrate.

[0045] Forty parts of polymethyl methacrylate carboxybetaine with a number-average molecular weight of 3500 g / mol and 0.5 parts of ethanol solution (water to ethanol volume ratio of 8:2) were placed in a beaker and stirred at 25°C until completely dissolved. After hydration for 3 hours, the mixture was allowed to stand for 10 hours. Then, 32 parts of sulfobetaine methacrylate and 22 parts of carboxybetaine methacrylate were added sequentially and stirred until fully mixed. Finally, 0.5 parts of Irgacure 1173 were added and the mixture was degassed under vacuum for 15 minutes to obtain the functional monomer mixture.

[0046] Under light-protected conditions and with the ambient temperature controlled at 3°C, the semi-cured silicone hydrogel substrate was immersed in a mixture of functional monomers for 20 minutes. After immersion, it was removed and subjected to two-stage photopolymerization. The light intensity for the first stage was set to 1 mW / cm². 2 The light intensity was set to 6 mW / cm² for the second segment, lasting for 1 minute. 2 The polymerization process was carried out for 8 minutes. After polymerization, the sample was sequentially extracted with ethanol, ethanol aqueous solution, and deionized water. Then, it was hydrated in PBS buffer for 30 hours and then stabilized in a 0.9 wt% sodium chloride solution for 50 hours. Finally, it was sterilized to obtain moisturizing and stain-resistant contact lenses.

[0047] Example 2

[0048] 40 parts of tris(trimethylsiloxy)propyl methacrylate, 20 parts of siloxane methacrylate, 15 parts of N,N-dimethylacrylamide, 1.5 parts of methacrylic acid, 0.5 parts of ethylene glycol dimethacrylate, 0.7 parts of Irgacure 2959 and 18.3 parts of tert-butanol were placed in a beaker, mixed evenly, and then injected into a contact lens mold. The mold was placed under a nitrogen inert atmosphere for photopolymerization prepolymerization. After prepolymerization was completed, the mold was demolded to obtain a semi-cured silicone hydrogel substrate.

[0049] 35 parts of polymethyl methacrylate carboxybetaine with a number-average molecular weight of 4500 g / mol and 0.5 parts of ethanol solution (water to ethanol volume ratio of 8:2) were placed in a beaker and stirred at 28°C until completely dissolved. After hydration for 3 hours, the mixture was allowed to stand for 11 hours. Then, 35 parts of sulfobetaine methacrylate and 25 parts of carboxybetaine methacrylate were added sequentially and stirred until fully mixed. Finally, 0.5 parts of Irgacure 2959 were added and the mixture was degassed under vacuum for 15 minutes to obtain the functional monomer mixture.

[0050] Under light-protected conditions and with the ambient temperature controlled at 5°C, the semi-cured silicone hydrogel substrate was immersed in a mixture of functional monomers for 20 minutes. After immersion, it was removed and subjected to two-stage photopolymerization. The light intensity for the first stage was set to 1.5 mW / cm². 2 The light intensity was set to 6.5 mW / cm² for the second segment, lasting 1.5 minutes. 2 The polymerization process was carried out for 10 minutes. After polymerization, the sample was sequentially extracted with ethanol, ethanol aqueous solution, and deionized water. Then, it was hydrated in PBS buffer for 30 hours and then stabilized in a 0.9 wt% sodium chloride solution for 52 hours. Finally, it was sterilized to obtain moisturizing and stain-resistant contact lenses.

[0051] Example 3

[0052] 42 parts of tris(trimethylsiloxy)propyl methacrylate, 22 parts of siloxane methacrylate, 15 parts of N,N-dimethylacrylamide, 1.5 parts of methacrylic acid, 0.5 parts of ethylene glycol dimethacrylate, 0.7 parts of Irgacure 1173 and 19.3 parts of tert-butanol were placed in a beaker, mixed evenly, and then injected into a contact lens mold. The mold was placed under a nitrogen inert atmosphere for photopolymerization prepolymerization. After prepolymerization was completed, the mold was demolded to obtain a semi-cured silicone hydrogel substrate.

[0053] 30 parts of polymethyl methacrylate carboxybetaine with a number average molecular weight of 5500 g / mol and 0.5 parts of ethanol solution (water to ethanol volume ratio of 8:2) were placed in a beaker and stirred at 30°C until completely dissolved. After hydration for 3 hours, the mixture was allowed to stand for 12 hours. Then, 38 parts of sulfobetaine methacrylate and 28 parts of carboxybetaine methacrylate were added sequentially and stirred until fully mixed. Finally, 0.5 parts of Irgacure 1173 were added and the mixture was degassed under vacuum for 15 minutes to obtain the functional monomer mixture.

[0054] Under light-protected conditions and with the ambient temperature controlled at 4°C, the semi-cured silicone hydrogel substrate was immersed in a mixture of functional monomers for 20 minutes. After immersion, it was removed and subjected to two-stage photopolymerization. The light intensity for the first stage was set to 2 mW / cm². 2 The light intensity was set to 7mW / cm² for the second segment, lasting for 2 minutes. 2 The polymerization process was carried out for 5 minutes. After polymerization, the sample was sequentially extracted with ethanol, ethanol aqueous solution, and deionized water. Then, it was hydrated in PBS buffer for 30 hours and then stabilized in a 0.9 wt% sodium chloride solution for 55 hours. Finally, it was sterilized to obtain moisturizing and stain-resistant contact lenses.

[0055] Comparative Example 1

[0056] Unlike Example 1, in this comparative example, the raw material system of the silicone hydrogel substrate and the raw material system of the functional monomer mixture were blended, and then the light intensity was set to 6 mW / cm². 2 Photopolymerization is performed once every 9 minutes to obtain moisturizing and stain-resistant contact lenses.

[0057] Comparative Example 2

[0058] Unlike Example 1, in this comparative example, the addition of carboxybetaine methacrylate to the functional monomer mixture was omitted, resulting in a moisturizing and stain-resistant contact lens.

[0059] Performance testing

[0060] The moisturizing performance, anti-fouling performance, basic performance and long-term stability of Examples 1-3 and Comparative Examples 1-2 were verified. Table 1 shows the test data for each performance.

[0061] Table 1. Performance data of the samples obtained in Examples 1-3 and Comparative Examples 1-2 BAC method; Place the lens with 10 8CFU / mL bacterial suspension was co-cultured at 37℃ for 4 h, followed by ultrasonic desorption and plate counting, with the substrate adhesion amount calculated as 1×10⁻⁶. 6 CFU / cm 2 count; ISO 18369-3:2017; The MTT assay (ISO 10993-5) was used to culture L929 cells. After MTT staining, the absorbance at 570 nm was measured, and the cell viability was calculated.

[0062] As can be seen from the above embodiments, the present invention provides a moisturizing and anti-fouling contact lens and its preparation method. Table 1 shows that the sample obtained in Comparative Example 1 was prepared using a physical blending method, resulting in a lack of gradient structure. Due to the functional materials being dispersed throughout the lens body, the surface concentration was insufficient, leading to poor anti-fouling performance. The uniform distribution of hydrophilic materials hindered oxygen permeability. Comparative Example 2 omitted the addition of CBMA, resulting in the functional layer of the obtained sample losing the anchoring of carboxyl groups, insufficient bonding with the lens body, accelerated aging and loss of the functional layer, and a significant decrease in anti-fouling ability.

[0063] Examples 1-3, by adjusting the ratio of the silicone hydrogel substrate and the composition of the betaine functional layer, constructed moisturizing and anti-fouling contact lenses with a gradient structure, whose performance was superior to the comparative examples. This invention employs semi-cured substrate impregnation and two-stage photopolymerization to firmly graft the betaine functional layer onto the substrate, resulting in a high concentration and uniform distribution of surface functional groups. While ensuring the high oxygen permeability of the silicone hydrogel, it significantly improves the lens's hydrophilicity and its ability to resist protein adsorption and staining. With optimization of the siloxane component, betaine monomer content, and polymerization parameters, the lens's structural stability, moisturizing durability, and anti-fouling effect are further improved, resulting in excellent overall performance and making it more suitable for long-term wear.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A moisturizing and stain-resistant contact lens, characterized in that, Includes a silicone hydrogel substrate and a gradient betaine functional layer; The silicone hydrogel substrate is prepared from the following raw materials in parts by weight: 35-45 parts of tris(trimethylsiloxy)propyl methacrylate, 15-25 parts of siloxane methacrylate, 12-18 parts of N,N-dimethylacrylamide, 1-2 parts of methacrylic acid, 0.4-0.6 parts of ethylene glycol dimethacrylate, 0.5-0.8 parts of photoinitiator, and 15-22 parts of diluent; The gradient betaine functional layer is prepared from a mixture of functional monomers, which is prepared from raw materials comprising the following parts by mass: 30-40 parts of sulfobetaine methacrylate, 20-30 parts of carboxybetaine methacrylate, 30-40 parts of polymethyl methacrylate carboxybetaine, 0.4-0.6 parts of photoinitiator 2, and 0.2-3 parts of ethanol solution.

2. The moisturizing and stain-resistant contact lens according to claim 1, characterized in that, The photoinitiator 1 and photoinitiator 2 are independently Irgacure 1173 or Irgacure 2959; The diluent includes tert-butanol or ethylene glycol.

3. A moisturizing and stain-resistant contact lens according to claim 1 or 2, characterized in that, The number-average molecular weight of the polymethyl methacrylate carboxybetaine is 3000~6000 g / mol; In the ethanol solution, the volume ratio of water to ethanol is 7~9:1~3.

4. The method for preparing moisturizing and stain-resistant contact lenses according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1) Mix tris(trimethylsiloxy)propyl methacrylate, siloxane methacrylate, N,N-dimethylacrylamide, methacrylic acid, ethylene glycol dimethacrylate, photoinitiator 1 and diluent, then inject the mixture into a mold for prepolymerization, and obtain a semi-cured silicone hydrogel substrate after demolding. Step 2) Mix polymethyl methacrylate carboxy betaine and ethanol solution, stir, hydrate and stand in sequence, then add sulfobetaine methacrylate and carboxybetaine methacrylate in sequence until fully mixed, finally add photoinitiator 2, and degas under vacuum to obtain functional monomer mixture. Step 3) Under light-protected conditions, immerse the semi-cured silicone hydrogel substrate in a mixture of functional monomers, remove it, and carry out a polymerization reaction. After post-treatment, you will get contact lenses with moisturizing and anti-fouling effects.

5. The method for preparing moisturizing and stain-resistant contact lenses according to claim 4, characterized in that, In step 1), the prepolymerization is photopolymerization, and the prepolymerization is carried out in an inert atmosphere.

6. The method for preparing moisturizing and stain-resistant contact lenses according to claim 4 or 5, characterized in that, In step 2), the hydration temperature is 22~34℃, and the settling time is 8~14h.

7. The method for preparing moisturizing and stain-resistant contact lenses according to claim 6, characterized in that, In step 3), the semi-cured silicone hydrogel substrate is immersed in a functional monomer mixture at a temperature of 2-5°C for 15-35 minutes.

8. The method for preparing moisturizing and stain-resistant contact lenses according to claim 4 or 7, characterized in that, In step 3), the polymerization reaction is a two-stage polymerization, and the light intensity of the first stage polymerization is 1~2 mW / cm². 2 The time is 1-2 minutes, and the light intensity for the second polymerization stage is 5-8 mW / cm². 2 The time is 5-10 minutes.

9. The method for preparing moisturizing and stain-resistant contact lenses according to claim 8, characterized in that, In step 3), the post-processing includes sequential multi-stage extraction, hydration treatment, stabilization treatment and sterilization treatment.

10. The method for preparing moisturizing and stain-resistant contact lenses according to claim 9, characterized in that, The extractant for the multi-stage extraction includes one or more of ethanol, aqueous ethanol solution, and deionized water; The hydration treatment was performed in PBS buffer for 24-36 hours. The stabilization treatment was carried out in a sodium chloride solution for 48-60 hours.

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