Acrylic lens and production process thereof

Abstract

The acrylic lens comprises a lens substrate, an aspheric optical structure formed on at least one optical surface of the lens substrate, and a hard coating, a multi-layer antireflection film and an antifouling layer which are sequentially laminated and compounded on the surface of the aspheric optical structure, the lens matrix is formed by a copolymer of methyl methacrylate and a high-refractive-index aromatic monomer, inorganic nanoparticles with the surfaces modified by a silane coupling agent are uniformly dispersed in the copolymer, the particle size of the inorganic nanoparticles is 5-20 nm, and the content of the inorganic nanoparticles accounts for 1%-5% of the total mass of the lens matrix; and the hard coating is a diamond-like carbon-based film formed by a plasma enhanced chemical vapor deposition method. According to the acrylic lens, structures such as aromatic rings are introduced into a lens matrix, so that the intrinsic refractive index of a material is improved, the thicknesses of the center and the edge of the lens are reduced under the same diopter, and the thinness and the light weight of the lens are realized.

Description

Technical Field

[0001] This invention relates to the field of acrylic lens technology, and in particular to an acrylic lens. Background Technology

[0002] Acrylic lenses, which are optical lenses made primarily of polymethyl methacrylate (PMMA), are widely used in eyeglasses, optical instruments, lighting equipment, display panels, and various window protection applications due to their advantages such as low density, high light transmittance (up to 92% or more), excellent processing performance, and relatively low cost.

[0003] However, as optical products continue to develop towards high performance, lightweight, durability and visual comfort, the inherent limitations of traditional acrylic lenses in terms of material properties, optical design and surface functions are becoming increasingly prominent, making it difficult to meet the demanding requirements of high-end application scenarios. Existing technologies suffer from the following main problems: inherent defects in the overall performance of materials. Although traditional pure PMMA materials have good light transmittance, their hardness is low (pencil hardness is usually only around 2H) and their impact resistance is insufficient. They are easily scratched or even broken when subjected to friction, scratches, or accidental impacts, and their durability is far inferior to that of glass lenses. Optical aberrations and limited field of vision. Most traditional acrylic lenses use a single spherical design. When correcting vision, especially at medium to high refractive errors, spherical lenses will produce obvious spherical aberrations and astigmatism. Insufficient surface functional protection. To improve surface hardness, the industry generally uses spraying or dipping with UV-cured silicone hard coatings. The hardness improvement of such coatings is limited (usually not exceeding 3H), and the wear resistance is still not ideal. Moreover, the adhesion to the substrate may decrease after long-term use or thermal cycling. In terms of anti-reflection treatment, most are simple single-layer or double-layer coatings, which have limited reduction in reflectivity (residual reflectivity is often above 1.5%), cannot effectively eliminate glare, and have poor anti-reflection effect over a wide spectral range. Summary of the Invention

[0004] Therefore, it is necessary to provide an acrylic lens that addresses the shortcomings of existing acrylic lenses in terms of mechanical strength, optical performance, surface durability, and lightweighting.

[0005] An acrylic lens includes a lens substrate, an aspherical optical structure formed on at least one optical surface of the lens substrate, and a hard coating, a multilayer anti-reflective film, and an anti-fouling layer sequentially stacked on the surface of the aspherical optical structure; the lens substrate is formed of a copolymer of methyl methacrylate and a high-refractive-index aromatic monomer, wherein inorganic nanoparticles modified with a silane coupling agent are uniformly dispersed in the copolymer, the particle size of the inorganic nanoparticles is 5-20 nm, and the content of the inorganic nanoparticles accounts for 1%-5% of the total mass of the lens substrate; the hard coating is a diamond-like carbon-based thin film formed by plasma-enhanced chemical vapor deposition.

[0006] In one embodiment, the high-refractive-index aromatic monomer is at least one of styrene, methylstyrene, or naphthyl acrylate, and its mass percentage in the copolymer is 10%-30%.

[0007] In one embodiment, the inorganic nanoparticles are at least one of nano-silica, nano-zirconia, or nano-titanium oxide.

[0008] In one embodiment, the multilayer antireflective film is a seven-layer film structure composed of alternating silicon dioxide and titanium dioxide layers, with the outermost layer being a silicon dioxide layer.

[0009] In one embodiment, the antifouling layer is a thin film composed of perfluoropolyether or fluorosilane compounds, with a thickness of 5-15 nm, so that the water contact angle on the lens surface is greater than 110° and the oil contact angle is greater than 70°.

[0010] A manufacturing process for producing acrylic lenses includes the following sequential steps: S1: Material pretreatment and blending: The dried methyl methacrylate monomer, high refractive index aromatic monomer, surface-modified inorganic nanoparticles and initiator are uniformly mixed and prepolymerized to obtain the modified prepolymer. S2: Precision injection molding: The modified prepolymer is injected into a precision temperature-controlled injection mold, the mold cavity having a preset aspherical curved surface; injection molding is performed under the process conditions of barrel temperature 230-250℃, mold temperature 80-90℃, and injection pressure 80-120MPa, followed by pressure holding, cooling, and demolding to obtain a lens substrate blank with an aspherical optical structure; S3: Annealing treatment: The lens substrate blank is placed in a programmable temperature-controlled oven and subjected to stepped annealing to eliminate internal stress; S4: Surface coating: On the aspherical optical structure surface of the lens substrate after plasma cleaning, a hard coating is deposited sequentially by plasma-enhanced chemical vapor deposition, a multilayer antireflection film is deposited by magnetron sputtering, and an antifouling layer is deposited by vacuum evaporation.

[0011] In one embodiment, the core of the injection mold in step S2 is machined by a single-point diamond turning process, and its surface accuracy PV value is less than 0.2 micrometers and its surface roughness Ra is less than 10 nanometers.

[0012] In one embodiment, the specific process of the stepped annealing in step S3 is as follows: first, maintain a constant temperature of 80°C for 2 hours, then cool down to 60°C at a rate of 10°C per hour, maintain the constant temperature for 2 hours, and finally cool down to room temperature with the furnace.

[0013] In one embodiment, when depositing the hard coating in step S4, methane and hydrogen are used as the reaction gas source, and plasma-enhanced chemical vapor deposition is performed under the conditions of substrate bias voltage of -200V to -400V and chamber pressure of 10-50Pa.

[0014] In one embodiment, during the prepolymerization process in step S1, supercritical carbon dioxide fluid is introduced into the mixing system at a pressure of 8-15 MPa and a temperature of 40-60°C.

[0015] The aforementioned acrylic lenses improve the intrinsic refractive index of the material by introducing structures such as aromatic rings into the lens matrix. This allows for a reduction in the thickness of the lens at the center and edges while maintaining the same refractive power, resulting in thinner and lighter lenses. Nanoparticles, acting as a rigid reinforcing phase, effectively hinder the propagation of microcracks within the material. Silane coupling agent modification ensures a good interfacial bond between the nanoparticles and the polymer matrix, preventing agglomeration. Together, these factors significantly enhance the hardness, elastic modulus, and impact toughness of the lens matrix, solving the problem of high brittleness in pure PMMA. The addition of inorganic nanoparticles increases the material's heat distortion temperature and reduces the coefficient of thermal expansion, making the lens more dimensionally stable and shape-retaining under high-temperature conditions. Furthermore, strict control of the nanoparticle size and dispersion uniformity minimizes light scattering, thereby enhancing mechanical properties while maintaining high light transmittance of the matrix material. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an acrylic lens in one embodiment. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0020] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0022] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0023] Please see Figure 1 This invention discloses an acrylic lens comprising: a lens substrate 10, an aspherical optical structure 20 formed on at least one optical surface of the lens substrate 10, and a hard coating 30, a multilayer antireflective film 40, and an antifouling layer 50 sequentially stacked on the surface of the aspherical optical structure 20; the lens substrate 10 is formed of a copolymer of methyl methacrylate and a high-refractive-index aromatic monomer, wherein inorganic nanoparticles modified with a silane coupling agent are uniformly dispersed in the copolymer, the particle size of the inorganic nanoparticles is 5-20 nm, and the content of the inorganic nanoparticles accounts for 1%-5% of the total mass of the lens substrate 10; the hard coating 30 is a diamond-like carbon-based thin film formed by plasma-enhanced chemical vapor deposition. The lens substrate 10 uses copolymerized modified PMMA and composite nanoparticles, which fundamentally improves the mechanical properties of the material, including hardness, toughness and thermal stability, while ensuring high light transmittance, lightweight and high refractive index. The aspherical design optimizes optical performance and reduces aberrations. The superposition of the surface gradient functional layer, namely the hard coating 30, the multi-layer anti-reflective film 40 and the anti-fouling layer 50, provides comprehensive surface protection and significantly enhances the lens's abrasion resistance, optical transmittance and easy cleaning, forming a systematic performance improvement solution from substrate to surface.

[0024] Furthermore, the high-refractive-index aromatic monomer is at least one of styrene, methylstyrene, or naphthyl acrylate, and its mass percentage in the copolymer is 10%-30%. Monomers such as styrene can effectively increase the refractive index of the copolymer, thereby achieving thinner lenses; and the above-mentioned specified range of high-refractive-index aromatic monomer content in the copolymer has been weighed and optimized. If it is too low, the refractive index increase will be limited, and if it is too high, it may lead to increased material brittleness and excessive decrease in the dispersion coefficient, affecting color difference performance.

[0025] Furthermore, the inorganic nanoparticles are at least one of nano-silica, nano-zirconia, or nano-titanium oxide. Nano-silica is mainly used to improve hardness and reduce the coefficient of thermal expansion; nano-zirconia is more effective in improving hardness and refractive index; nano-titanium oxide has both the function of improving refractive index and ultraviolet shielding. Depending on the different performance focuses, they can be used alone or in combination.

[0026] The aspherical optical structure 20 satisfies the surface shape defined by the following aspherical equation:

[0027] Where c is the curvature, k is the conic coefficient, and the value of k ranges from -0.8 to -1.2, and α1, α2, and α3 are higher-order aspheric coefficients.

[0028] This aspherical equation is a general description of higher-order aspherical surfaces. Limiting the conic coefficient k to the range of -0.8 to -1.2 is a typical value optimized for negative refractive power. It can effectively correct spherical aberration and astigmatism, and while ensuring central optical quality, it minimizes the thickness of the lens edge, achieving a balance between aesthetics and optical performance.

[0029] Furthermore, the multilayer antireflective film 40 is a seven-layer film structure composed of alternating silicon dioxide and titanium dioxide layers, with the outermost layer being a silicon dioxide layer. This seven-layer film system is an optimized structure for broadband antireflection in the visible light band. and It is the most stable combination of high and low refractive index materials in optical coatings, and the outermost layer is designed to be It is beneficial for bonding with the subsequent antifouling layer 50, and at the same time, it has good chemical stability and is resistant to environmental erosion.

[0030] A manufacturing process for producing acrylic lenses includes the following sequential steps: S1: Material pretreatment and blending: The dried methyl methacrylate monomer, high refractive index aromatic monomer, surface-modified inorganic nanoparticles and initiator are uniformly mixed and prepolymerized to obtain the modified prepolymer. S2: Precision injection molding: The modified prepolymer is injected into a precision temperature-controlled injection mold, the mold cavity having a preset aspherical curved surface; injection molding is performed under the process conditions of barrel temperature 230-250℃, mold temperature 80-90℃, and injection pressure 80-120MPa, followed by pressure holding, cooling, and demolding to obtain a lens substrate 10 blank with an aspherical optical structure 20; S3: Annealing treatment: The lens substrate 10 blank is placed in a programmable temperature controlled oven and subjected to stepped annealing to eliminate internal stress; S4: Surface coating: On the surface of the aspherical optical structure 20 of the lens substrate 10 after plasma cleaning, a hard coating 30 is deposited sequentially by plasma-enhanced chemical vapor deposition, a multilayer antireflection film 40 is deposited by magnetron sputtering, and an antifouling layer 50 is deposited by vacuum evaporation.

[0031] Step S1 ensures the uniform dispersion of modified materials and nanoparticles, which is a prerequisite for obtaining a homogeneous high-performance matrix. Step S2, through the combination of optimized precision injection molding parameters and aspherical molds, is the key to achieving high-precision optical surface profiles. Step S3, with its stepped annealing, effectively eliminates processing stress, ensuring optical stability and long-term dimensional stability. Step S4, with its multi-technology composite coating process, is the core of achieving a multifunctional protective layer on the surface. Each step is interconnected, jointly ensuring the controllability and reproducibility of the final product's performance.

[0032] Furthermore, the mold core of the injection mold described in step S2 is machined using a single-point diamond turning process, achieving a surface accuracy (PV) of less than 0.2 micrometers and a surface roughness (Ra) of less than 10 nanometers. Single-point diamond turning is one of the most precise methods for machining optical-grade aspherical metal molds. An accuracy of PV < 0.2 μm and Ra < 10 nm allows for the perfect replication of the mold's surface errors and textures onto the plastic lens, which is a fundamental prerequisite for ensuring the lens achieves diffraction-limited optical quality.

[0033] Furthermore, the specific process of the stepped annealing described in step S3 is as follows: first, maintain a constant temperature of 80°C for 2 hours, then cool to 60°C at a rate of 10°C per hour, maintain the constant temperature for another 2 hours, and finally cool to room temperature in the furnace. This slow, stepped cooling process allows sufficient time for the polymer chains to relax and rearrange, maximizing the release of internal molecular stresses frozen during injection molding. Compared to direct cooling or simple isothermal annealing, this method more effectively reduces lens birefringence, avoids optical distortion, and improves the long-term dimensional stability of the product.

[0034] Furthermore, in step S4, when depositing the hard coating 30, methane and hydrogen are used as the reaction gas sources, and plasma-enhanced chemical vapor deposition is performed under the conditions of a substrate bias voltage of -200V to -400V and a chamber pressure of 10-50Pa. Methane is the carbon source, and hydrogen helps to generate sp3 hybridized diamond-like carbon. The aforementioned bias voltage and pressure range is an optimized process window for forming a high-hardness, high-adhesion diamond-like carbon coating. Under these conditions, the deposited film exhibits excellent wear resistance (hardness ≥ 4H) and good optical transparency, and strong adhesion to the PMMA substrate.

[0035] Furthermore, during the prepolymerization process in step S1, supercritical carbon dioxide fluid is introduced into the mixing system. The supercritical carbon dioxide fluid has a pressure of 8-15 MPa and a temperature of 40-60°C. Supercritical carbon dioxide exhibits high diffusivity and low surface tension in polymer melts, and can be used as a physical foaming agent and viscosity modifier. Under these parameters, it can effectively reduce melt viscosity, improve the dispersion of nanoparticles, and potentially form microporous structures within the material. This helps reduce raw material usage (weight reduction) and may impart better thermal insulation or acoustic properties to the lenses, while the process is environmentally friendly and pollution-free.

[0036] Furthermore, the antifouling layer 50 is a thin film composed of perfluoropolyether or fluorosilane compounds, with a thickness of 5-15 nm, ensuring that the water contact angle on the lens surface is greater than 110° and the oil contact angle is greater than 70°. Perfluoropolyether or fluorosilane has extremely low surface energy; a thickness of 5-15 nm is sufficient to form a complete monomolecular film, ensuring effectiveness while avoiding excessive thickness that could affect optical performance; a water contact angle >110° and an oil contact angle >70° are typical characteristics of superhydrophobic and oleophobic surfaces, giving the lens excellent anti-fingerprint, anti-oil, and self-cleaning capabilities, making it easy to wipe and maintain.

[0037] In summary, the acrylic lens disclosed in this invention improves the intrinsic refractive index of the material by introducing structures such as aromatic rings into the lens matrix. This allows for a reduction in the center and edge thickness of the lens at the same refractive power, achieving thinner and lighter lenses. Nanoparticles, as a rigid reinforcing phase, effectively hinder the propagation of microcracks within the material. Silane coupling agent modification ensures good interfacial bonding between the nanoparticles and the polymer matrix, preventing agglomeration. The combined effect of these two factors significantly improves the hardness, elastic modulus, and impact toughness of the lens matrix, solving the problem of high brittleness in pure PMMA. The addition of inorganic nanoparticles increases the material's heat distortion temperature and reduces the coefficient of thermal expansion, resulting in stronger dimensional stability and shape retention of the lens under high-temperature conditions. Furthermore, strict control of the nanoparticle size and dispersion uniformity minimizes light scattering, thereby enhancing mechanical properties while maintaining high light transmittance of the matrix material.

[0038] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0039] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An acrylic lens, characterized in that, include: The lens substrate, an aspherical optical structure formed on at least one optical surface of the lens substrate, and a hard coating, a multilayer anti-reflective film and an anti-fouling layer sequentially stacked on the surface of the aspherical optical structure; The lens matrix is ​​formed by a copolymer of methyl methacrylate and a high-refractive-index aromatic monomer. The copolymer contains inorganic nanoparticles with a surface modified by a silane coupling agent. The particle size of the inorganic nanoparticles is 5-20 nm, and the content of the inorganic nanoparticles accounts for 1%-5% of the total mass of the lens matrix. The hard coating is a diamond-like carbon-based thin film formed by plasma-enhanced chemical vapor deposition.

2. The acrylic lens according to claim 1, characterized in that, The high-refractive-index aromatic monomer is at least one of styrene, methylstyrene, or naphthyl acrylate, and its mass percentage in the copolymer is 10%-30%.

3. The acrylic lens according to claim 1, characterized in that, The inorganic nanoparticles are at least one of nano-silica, nano-zirconia, or nano-titanium oxide.

4. The acrylic lens according to claim 1, characterized in that, The multilayer antireflective film is a seven-layer film structure composed of alternating silicon dioxide and titanium dioxide layers, with the outermost layer being a silicon dioxide layer.

5. The acrylic lens according to claim 1, characterized in that, The antifouling layer is a thin film composed of perfluoropolyether or fluorosilane compounds, with a thickness of 5-15nm, so that the water contact angle on the lens surface is greater than 110° and the oil contact angle is greater than 70°.

6. A manufacturing process for producing the acrylic lens according to any one of claims 1 to 5, comprising the following sequential steps: S1: Material pretreatment and blending: The dried methyl methacrylate monomer, high refractive index aromatic monomer, surface-modified inorganic nanoparticles and initiator are uniformly mixed and prepolymerized to obtain the modified prepolymer. S2: Precision injection molding: The modified prepolymer is injected into a precision temperature-controlled injection mold, the mold cavity having a preset aspherical curved surface; injection molding is performed under the process conditions of barrel temperature 230-250℃, mold temperature 80-90℃, and injection pressure 80-120MPa, followed by pressure holding, cooling, and demolding to obtain a lens substrate blank with an aspherical optical structure; S3: Annealing treatment: The lens substrate blank is placed in a programmable temperature-controlled oven and subjected to stepped annealing to eliminate internal stress; S4: Surface coating: On the aspherical optical structure surface of the lens substrate after plasma cleaning, a hard coating is deposited sequentially by plasma-enhanced chemical vapor deposition, a multilayer antireflection film is deposited by magnetron sputtering, and an antifouling layer is deposited by vacuum evaporation.

7. The acrylic lens according to claim 6, characterized in that, The core of the injection mold described in step S2 is machined by single-point diamond turning, and its surface accuracy PV value is less than 0.2 micrometers and its surface roughness Ra is less than 10 nanometers.

8. The acrylic lens according to claim 6, characterized in that, The specific process of the stepped annealing described in step S3 is as follows: first, maintain a constant temperature of 80°C for 2 hours, then cool down to 60°C at a rate of 10°C per hour, maintain the constant temperature for 2 hours, and finally cool down to room temperature with the furnace.

9. The acrylic lens according to claim 6, characterized in that, In step S4, when depositing the hard coating, methane and hydrogen are used as the reaction gas source, and plasma-enhanced chemical vapor deposition is performed under the conditions of substrate bias voltage of -200V to -400V and chamber pressure of 10-50Pa.

10. The acrylic lens according to claim 6, characterized in that, In the prepolymerization process of step S1, supercritical carbon dioxide fluid is introduced into the mixing system. The pressure of the supercritical carbon dioxide fluid is 8-15 MPa and the temperature is 40-60℃.

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