Ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect and preparation method of ultra-wide-angle antireflection film

Abstract

The invention discloses an ultra-wide-angle antireflection film based on thin film interference and a sub-wavelength effect and a preparation method of the ultra-wide-angle antireflection film. The antireflection film comprises a transparent base material, a gradient refractive index structure layer, a micro-nano structure layer and a protective layer which are sequentially stacked. According to the invention, a micro-nano composite layered structure broadband wide-angle antireflection film with a laminated optical medium-three-dimensional periodic microstructure is prepared by using a roll-to-roll magnetron sputtering and nanoimprint technology, and compared with a single multi-layer medium antireflection film, the wide-angle antireflection film provided by the invention widens the visual angle; compared with an antireflection film with a single micro-nano structure, under the condition of ensuring antireflection of a large visual angle (0-60 degrees) and a wide wave band (380-1100 nm), the high aspect ratio characteristic of the micro-nano structure is reduced, the anti-damage effect can be improved, the micro-nano structure is not limited by the harsh requirement of the precision of a nanoscale micro-nano machining technology any more, and the anti-reflection film is more suitable for large-area and batch roll-to-roll type production.

Description

Technical Field

[0001] The present invention relates to the field of antireflection film materials, and particularly to an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect and a preparation method thereof. Background Art

[0002] As a carrier for human-computer interaction, the screen can bring an excellent visual experience. With the iterative upgrade of optical design, processing technology, and display technology, screen display technologies such as in-vehicle displays, smartphones, and tablets need to prepare antireflection films (AR films, Anti-Reflection) on the surface of the display window to improve display clarity, reduce reflection, increase color gamut, and enhance strong-light visibility. With the improvement of consumers' visual experience in different application scenarios, viewing angles, and colors in screen display technologies, conventional antireflection films can no longer meet the usage requirements.

[0003] Currently, antireflection films can be divided into two categories according to the antireflection structure: one is the antireflection based on isotropic uniform single-layer or simple multi-layer dielectric films. Its principle is to make the reflected light from the upper and lower interfaces interfere destructively by selecting or constructing thin films with appropriate optical parameters to achieve the purpose of antireflection and increased transmittance. This method has a simple principle. Through material design, artificial structures or materials with appropriate equivalent optical parameters can be screened out, but the low-refractive-index materials in nature are extremely limited. The refractive index of MgF2 in the visible light band is 1.38, which limits the design of AR films to a certain extent and it is difficult to achieve antireflection effects with a wide spectrum and wide angle. The other is the micro-nano structure antireflection based on the sub-wavelength effect. Its working principle is to construct a periodic micro-structure system with a gradient change in the structure scale along the light incident direction, forming a gradual transition of the refractive index from air to the substrate medium, reducing the Fresnel reflection caused by the sudden change in the refractive index. Compared with the antireflection of multi-layer dielectric films, it can achieve wide-band and omnidirectional antireflection. However, its micro-nano structure must have a certain aspect ratio characteristic, which poses a severe challenge to the form of the material and the process accuracy. In addition, the high-aspect-ratio structures are sparsely arranged on the substrate surface, and the anti-environmental damage performance decreases. Therefore, the research on antireflection films with omnidirectional antireflection, "one-piece black" effect, and anti-environmental damage performance has broad industrialization prospects. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect and a preparation method thereof in view of the above-mentioned deficiencies in the prior art.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is: in the first aspect of the present invention, an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect is provided, which includes a transparent substrate, a gradient refractive index structure layer, a micro-nano structure layer, and a protective layer stacked in sequence;

[0006] The gradient refractive index structure layer includes a first refractive index material layer, a second refractive index material layer, and a residual layer that are sequentially stacked from the side of the transparent substrate.

[0007] Preferably, the refractive indices of the material of the first refractive index material layer, the material of the second refractive index material layer, and the material of the residual layer at 550 nm are denoted as n1, n2, and n3 respectively, and satisfy: 1.45 ≤ n1 ≤ 1.8, 1.38 ≤ n2 ≤ 1.55, 1.3 ≤ n3 ≤ 1.5.

[0008] Preferably, the material of the first refractive index material layer is AL2O3, or a mixture of AL2O3 and SiO2, and the mass ratio of SiO2 is not more than 50%; the thickness of the first refractive index material layer is 60 - 100 nm.

[0009] Preferably, the material of the second refractive index film layer is one of SiO2, a mixture of AL2O3 and SiO2 (SiO2 accounts for ≥ 50%), and MgF2. When the material of the second refractive index film layer is a mixture of AL2O3 and SiO2, the mass ratio of SiO2 is not less than 50%; the thickness of the second refractive index film layer is 30 - 70 nm.

[0010] Preferably, the residual layer is an ultraviolet curable resin with a thickness of 50 - 90 nm.

[0011] Preferably, the micro-nano structure layer is composed of a quadrangular frustum micro-nano structure array. The material of the micro-nano structure layer is an ultraviolet curable resin, and the refractive index n4 at 550 nm satisfies: 1.3 ≤ n4 ≤ 1.5.

[0012] Preferably, the height of the quadrangular frustum micro-nano structure is H, the long side width of the bottom end is D, the long side width of the top end is d, and the periodic repetition of the quadrangular frustum micro-nano structure is P, and satisfies:

[0013] H:D = 1.5:1, H = 120 nm - 240 nm, D = 80 nm - 180 nm, d = 10 nm - 80 nm, P = 160 nm - 240 nm.

[0014] Preferably, the material of the protective layer is one of silicon dioxide, silicon nitride compound, and aluminum oxide, and the thickness is 1 - 20 nm.

[0015] In the second aspect of the present invention, a method for preparing an ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect as described above is provided, including the following steps:

[0016] S1. Perform plasma treatment on the transparent substrate;

[0017] S2. Prepare the first refractive index material layer on the transparent substrate after plasma treatment by using a roll-to-roll magnetron sputtering process;

[0018] S3. Prepare the second refractive index film layer on the first refractive index material layer by using a roll-to-roll magnetron sputtering process;

[0019] S4. Form a residual layer and a micro-nano structure layer on the second refractive index film layer through a roll-to-roll nanoimprinting process;

[0020] S5. Prepare a protective layer on the surface of the micro-nano structure layer by using a magnetron sputtering, electron beam evaporation or atomic layer deposition process, and finally obtain an ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect.

[0021] Preferably, the method for preparing the ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect includes the following steps:

[0022] S1. First, perform plasma treatment on the transparent substrate. The power of the plasma treatment is 200 - 500 W. Use a mixed gas of Ar and O2 as the gas source, with an Ar flow rate of 30 - 80 sccm, an O2 flow rate of 350 - 450 sccm, and a linear velocity of 0.3 - 1 m / min;

[0023] S2. Prepare the first refractive index material layer on the transparent substrate after plasma treatment by using a roll-to-roll magnetron sputtering process. Use a mixed gas of Ar and O2 for reactive sputtering. The power of the rotating target is 9000 - 13000 W, the Ar flow rate is 50 - 100 sccm, the O2 flow rate is 50 - 100 sccm, and the linear velocity is 0.3 - 1 m / min;

[0024] S3. Prepare the second refractive index film layer on the first refractive index material layer by using a roll-to-roll magnetron sputtering process. Use a mixed gas of Ar and O2 for reactive sputtering. The power of the rotating target is 8000 - 1000 W, the Ar flow rate is 50 - 100 sccm, the O2 flow rate is 50 - 100 sccm, and the linear velocity is 0.3 - 1 m / min;

[0025] S4. Form a residual layer and a micro-nano structure layer on the second refractive index film layer through a roll-to-roll nanoimprinting process:

[0026] Coat an ultraviolet-curable resin on the second refractive index material layer to form an imprinted ultraviolet-curable resin layer, and press an imprinting template containing a frustum micro-nano structure array pattern into the imprinted ultraviolet-curable resin layer; after ultraviolet curing and shaping, demold, and transfer the frustum micro-nano structure array pattern on the imprinting template to the imprinted ultraviolet-curable resin layer to form a micro-nano structure layer. The imprinted ultraviolet-curable resin layer between the micro-nano structure layer and the second refractive index material layer forms a residual layer. The process parameters of the imprinting process are: the imprinting pressure is 3-10 bar, the wavelength of the ultraviolet curing light source is 315-450 nm, the curing energy is 4-8 J / cm 2 , and the imprinting speed is 0.5-1.5 m / min;

[0027] S5. Prepare a protective layer on the surface of the micro-nano structure layer by using a roll-to-roll magnetron sputtering process. Reactively sputter using a mixed gas of Ar and O2. The coating power is 8000-10000 W, the Ar flow rate is 50-100 sccm, the O2 flow rate is 50-100 sccm, and the linear speed is 1-3 m / min; finally, obtain an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect.

[0028] The beneficial effects of the present invention are:

[0029] The present invention provides an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect and a preparation method thereof. The present invention uses a roll-to-roll magnetron sputtering and nanoimprinting process to prepare a micro-nano composite layer structure wide-band wide-angle antireflection film with a "stacked optical medium-three-dimensional periodic micro-structure". Compared with a single multi-layer dielectric antireflection film, the present invention broadens the viewing angle; compared with a single micro-nano structure antireflection film, while ensuring antireflection in a large viewing angle (0°-60°) and a wide band (380-1100 nm), the present invention reduces the high aspect ratio characteristics of the micro-nano structure, can improve the anti-damage effect, and is no longer limited by the harsh requirements of the nano-level micro-nano processing technology precision, and is more suitable for large-area and batch roll-to-roll production; in addition, the present invention uses a roll-to-roll magnetron sputtering process to deposit a high-transmittance protective layer, which can further enhance the anti-damage effect. Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of the ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect of the present invention;

[0031] Figure 2 It is a schematic structural diagram of the frustum micro-nano structure of the present invention;

[0032] Figure 3 It is a reflection spectrum diagram of the wide-band wide-angle antireflection film prepared in Example 1 at different incident angles;

[0033] Figure 4Schematic structural diagram of the antireflection film of Comparative Example 1;

[0034] Figure 5 Reflectance spectra of the antireflection film of Comparative Example 1 at different incident angles. Specific embodiments

[0035] The following further describes the present invention in detail with reference to embodiments, so that those skilled in the art can implement it according to the description in the specification.

[0036] It should be understood that terms such as "having", "including", and "comprising" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0037] Unless otherwise specified, the test methods used in the following examples are all conventional methods. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified. For those not specifying specific conditions in the following examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be purchased commercially.

[0038] To overcome the restriction of high aspect ratio on micro-nano processing technology in sub-wavelength micro-nano structure surface technology and the limitation of antireflection performance by incident angle in optical antireflection thin film technology, the present invention proposes a micro-nano composite laminated antireflection film with a "laminated optical medium - three-dimensional periodic microstructure" and its preparation method. On the premise of achieving wide-band wide-angle near "zero" reflection and improving display color neutrality, it simultaneously realizes reducing the aspect ratio and increasing the anti-damage performance; making it no longer limited by the multi-layer structure design of multi-layer dielectric antireflection films, the refractive index of materials, and the stringent requirements of high-precision micro-nano processing technology.

[0039] Referring to Figure 1 , the present invention provides an ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect, including a transparent substrate, a gradient refractive index structure layer, a micro-nano structure layer, and a protective layer stacked in sequence;

[0040] The gradient refractive index structure layer includes a first refractive index material layer, a second refractive index material layer, and a residual layer stacked in sequence from the side of the transparent substrate.

[0041] The transparent substrate is made of a transparent material capable of transmitting light in the visible light region. Within the range that does not damage the effects of the present invention, a material with a light transmittance of 80% or more in the visible light wavelength region is used. The transparent substrate can be a sheet or a roll of one of the following materials: high molecular resin materials such as polyethylene naphthalate (PEN), polyethylene terephthalate (PET), triacetyl cellulose (TAC), cycloolefin copolymer (COP), cycloolefin polymer (COC), polycarbonate (PC), etc. The transparent substrate can also be an inorganic substrate, which can be a glass film. The transparent substrate can also be a film material imparted with optical and / or physical functions. For example, it can be a hardening film, an antiglare film, a polarizing plate, a retardation compensation film, an electromagnetic shielding film, a transparent conductive film, a brightness enhancement film, a barrier film, etc. It is preferably a roll of PET or TAC containing a hardening coating / antiglare hard coating. The thickness of the transparent substrate is not particularly limited, but is usually 25 - 200 μm, preferably 50 - 90 μm. The surface of the transparent substrate can be pre-treated by sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, solvent cleaning, ultrasonic cleaning, etc. The surface of the transparent substrate can be dust-removed and cleaned, and the adhesion of the gradient refractive index structure layer on the transparent substrate can be improved.

[0042] In a preferred embodiment, the refractive indices of the material of the first refractive index material layer, the material of the second refractive index material layer, and the material of the remaining layer at 550 nm are denoted as n1, n2, and n3 in sequence, satisfying: 1.45 ≤ n1 ≤ 1.8, 1.38 ≤ n2 ≤ 1.55, 1.3 ≤ n3 ≤ 1.5.

[0043] In a preferred embodiment, the material of the first refractive index material layer is AL2O3, or a mixture of AL2O3 and SiO2, and the mass ratio of SiO2 does not exceed 50%; the thickness of the first refractive index material layer is 60 - 100 nm.

[0044] In a preferred embodiment, the material of the second refractive index film layer is one of SiO2, a mixture of AL2O3 and SiO2 (SiO2 accounts for ≥ 50%), and MgF2. When the material of the second refractive index film layer is a mixture of AL2O3 and SiO2, the mass ratio of SiO2 is not less than 50%; the thickness of the second refractive index film layer is 30 - 70 nm.

[0045] In a preferred embodiment, the remaining layer is an ultraviolet curable resin, including but not limited to epoxy acrylate, polyurethane acrylate, polyester acrylate, polyether acrylate, amino acrylate, acrylate, and other acrylates, with a thickness of 50 - 90 nm.

[0046] In a preferred embodiment, the first refractive index material layer and the second refractive index material layer are formed on the transparent substrate by a magnetron sputtering process; the residual layer is formed on the second refractive index material layer by a nanoimprint process.

[0047] In a preferred embodiment, the micro-nano structure layer is composed of a quadrangular frustum micro-nano structure array, and the material of the micro-nano structure layer is an ultraviolet curable resin, including but not limited to epoxy acrylate, polyurethane acrylate, polyester acrylate, polyether acrylate, amino acrylate, acrylate and other acrylates; the refractive index n4 at 550 nm satisfies: 1.3 ≤ n4 ≤ 1.5.

[0048] In a preferred embodiment, referring to Figure 2 , for the quadrangular frustum micro-nano structure, the height is H, the long side width of the bottom end is D, the long side width of the top end is d, and the periodic repetition of the quadrangular frustum micro-nano structure is P, satisfying:

[0049] H:D = 1.5:1, H = 120 nm - 240 nm, D = 80 nm - 180 nm, d = 10 nm - 80 nm, P = 160 nm - 240 nm.

[0050] When the shapes of the bottom and top of the quadrangular frustum micro-nano structure are regular quadrilaterals, the widths of the sides at the bottom end are equal, all being D; the widths of the sides at the top end are equal, all being d. In the figure, γ represents the angle between the side and the bottom of the quadrangular frustum micro-nano structure, and θ represents the incident angle.

[0051] In a preferred embodiment, the micro-nano structure layer is prepared by a nanoimprint process.

[0052] The protective layer is located on the outermost surface of the micro-nano structure layer to protect against wear of the micro-nano structure layer. When applied to a touch panel, etc., the protective layer can effectively increase the damage resistance hardness of the micro-nano structure layer and improve the environmental adaptability of the micro-nano structure layer. In a preferred embodiment, the material of the protective layer is one of silicon dioxide, silicon nitride compound, and aluminum oxide, and the thickness is 1 - 20 nm.

[0053] In a preferred embodiment, the protective layer 4 can be prepared by processes such as magnetron sputtering, electron beam evaporation, or atomic layer deposition.

[0054] The present invention also provides a preparation method of the ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect as described above, including the following steps:

[0055] S1. Perform plasma treatment on the transparent substrate;

[0056] S2. Prepare the first refractive index material layer on the plasma-treated transparent substrate by a roll-to-roll magnetron sputtering process;

[0057] S3. Prepare the second refractive index film layer on the first refractive index material layer by using a roll-to-roll magnetron sputtering process;

[0058] S4. Form a residual layer and a micro-nano structure layer on the second refractive index film layer through a roll-to-roll nanoimprinting process;

[0059] S5. Prepare a protective layer on the surface of the micro-nano structure layer by using a magnetron sputtering, electron beam evaporation or atomic layer deposition process, and finally obtain an ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect.

[0060] In a preferred embodiment, the method for preparing an ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect includes the following steps:

[0061] S1. First, perform plasma treatment on the transparent substrate. The power of the plasma treatment is 200 - 500W. Use a mixed gas of Ar and O2 as the gas source, with an Ar flow rate of 30 - 80 sccm, an O2 flow rate of 350 - 450 sccm, and a linear velocity of 0.3 - 1 m / min;

[0062] S2. Prepare the first refractive index material layer on the plasma-treated transparent substrate by using a roll-to-roll magnetron sputtering process. Perform reactive sputtering with a mixed gas of Ar and O2. The power of the rotating target is 9000 - 13000W, the Ar flow rate is 50 - 100 sccm, the O2 flow rate is 50 - 100 sccm, and the linear velocity is 0.3 - 1 m / min;

[0063] S3. Prepare the second refractive index film layer on the first refractive index material layer by using a roll-to-roll magnetron sputtering process. Perform reactive sputtering with a mixed gas of Ar and O2. The power of the rotating target is 8000 - 1000W, the Ar flow rate is 50 - 100 sccm, the O2 flow rate is 50 - 100 sccm, and the linear velocity is 0.3 - 1 m / min;

[0064] S4. Form a residual layer and a micro-nano structure layer on the second refractive index film layer through a roll-to-roll nanoimprinting process:

[0065] Coat and apply a UV-curable resin on the second refractive index material layer to form an imprinting UV-curable resin layer. Press an imprinting template containing a quadrangular pyramid micro-nano structure array pattern into the imprinting UV-curable resin layer; after UV curing and shaping, demold. The quadrangular pyramid micro-nano structure array pattern on the imprinting template is transferred to the imprinting UV-curable resin layer to form a micro-nano structure layer, and the imprinting UV-curable resin layer between the micro-nano structure layer and the second refractive index material layer forms a residual layer. The process parameters of the imprinting process are: the imprinting pressure is 3 - 10 bar, the wavelength of the UV-curing light source is 315 - 450 nm, the curing energy is 4 - 8 J / cm 2 , and the imprinting speed is 0.5 - 1.5 m / min;

[0066] S5. A protective layer is prepared on the surface of the micro-nano structure layer by using a roll-to-roll magnetron sputtering process. Reactive sputtering is carried out with a mixed gas of Ar and O2. The coating power is 8000 - 10000 W, the Ar flow rate is 50 - 100 sccm, the O2 flow rate is 50 - 100 sccm, and the linear velocity is 1 - 3 m / min; finally, an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect is obtained.

[0067] The present invention utilizes the precise regulation ability of stacked optical media and three-dimensional periodic microstructures for large-angle incident light and wide band, combines roll-to-roll magnetron sputtering and nanoimprinting technologies, and innovatively designs and prepares a wide-band wide-angle antireflection film, which can achieve ultra-low reflection and "one-piece black" display effect in the visible light and near-infrared bands within the range of 0° - 60°, and also has environmental damage resistance and bending resistance.

[0068] The above is the overall concept of the present invention. The following provides detailed examples and comparative examples on this basis to further illustrate the present invention.

[0069] Example 1

[0070] An ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect, comprising a transparent substrate, a gradient refractive index structure layer, a micro-nano structure layer, and a protective layer stacked in sequence;

[0071] The gradient refractive index structure layer includes a first refractive index material layer, a second refractive index material layer, and a residual layer stacked in sequence from the side of the transparent substrate.

[0072] The transparent substrate is a poly(ethylene terephthalate) (PET) coil with a thickness of 75 μm. The thicknesses of the first refractive index material layer, the second refractive index material layer, and the residual layer are 80 nm, 47 nm, and 70 nm in sequence; the thickness of the protective layer is 10 nm.

[0073] The height of the frustum micro-nano structure is H, the long side width of the bottom end is D, the long side width of the top end is d, and the periodic repetition of the frustum micro-nano structure is P, satisfying:

[0074] H:D = 1.5:1, H = 180 nm, D = 120 nm, d = 40 nm, P = 200 nm.

[0075] The materials of the first refractive index material layer, the second refractive index material layer, and the residual layer are denoted as n1, n2, and n3 respectively at 550 nm, satisfying: 1.45 ≤ n1 ≤ 1.8, 1.38 ≤ n2 ≤ 1.55, 1.3 ≤ n3 ≤ 1.5. The material of the micro-nano structure layer is an ultraviolet curable resin, and the refractive index n4 at 550 nm satisfies: 1.3 ≤ n4 ≤ 1.5.

[0076] The preparation method of the ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect includes the following steps:

[0077] S1. First, perform plasma treatment on the transparent substrate. The power of the plasma treatment is 350W. Use a mixed gas of Ar and O2 as the gas source, with an Ar flow rate of 55 sccm, an O2 flow rate of 400 sccm, and a linear velocity of 0.6 m / min.

[0078] S2. Use the roll-to-roll magnetron sputtering process to prepare the first refractive index material layer on the plasma-treated transparent substrate. The material of the first refractive index material layer is a mixture of AL2O3 and SiO2 (the mass ratio of SiO2 ≤ 50%).

[0079] The sputtering process parameters are as follows: Use a SiAl rotating target, and the mass ratio of Si:Al in the SiAl target is 30:70. Use a mixed gas of Ar and O2 for reactive sputtering. The rotating target power is 11000W, the Ar flow rate is 75 sccm, the O2 flow rate is 75 sccm, and the linear velocity is 0.6 m / min.

[0080] S3. Use the roll-to-roll magnetron sputtering process to prepare the second refractive index film layer on the first refractive index material layer. The material of the second refractive index material layer is SiO2. The sputtering process parameters are as follows: Use a Si rotating target, use a mixed gas of Ar and O2 for reactive sputtering. The rotating target power is 9000W, the Ar flow rate is 75 sccm, the O2 flow rate is 75 sccm, and the linear velocity is 0.6 m / min.

[0081] S4. Form a residual layer and a micro-nano structure layer on the second refractive index film layer through the roll-to-roll nanoimprinting process:

[0082] Coat and apply a UV-curable resin (UV-curable resin of model MM1078 from Morphotonics) on the second refractive index material layer to form an imprinted UV-curable resin layer. Press an imprinting template containing a quadrangular pyramid micro-nano structure array pattern into the imprinted UV-curable resin layer. After UV curing and shaping, demold. The quadrangular pyramid micro-nano structure array pattern on the imprinting template is transferred to the imprinted UV-curable resin layer to form a micro-nano structure layer, and the imprinted UV-curable resin layer between the micro-nano structure layer and the second refractive index material layer forms a residual layer. The process parameters during the imprinting process are as follows: The imprinting pressure is 6.5 bar, the wavelength of the UV-curing light source is 380 nm, the curing energy is 6 J / cm 2 , and the imprinting speed is 1 m / min.

[0083] S5. A protective layer is prepared on the surface of the micro-nano structure layer by a roll-to-roll magnetron sputtering process. Reactive sputtering is carried out using a mixed gas of Ar and O2. The coating power is 9000 W, the Ar flow rate is 75 sccm, the O2 flow rate is 75 sccm, and the linear velocity is 2 m / min. The protective layer material is silicon dioxide (SiO2); finally, an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect is obtained.

[0084] Refer to Figure 3 , which is the reflection spectrum diagram of the wide-band wide-angle antireflection film prepared in Example 1 at different incident angles. In the wavelength range of 380 - 1100 nm, the average reflectivity at an incident angle of 8° is <0.4%, and the reflection color phase a* = 0 ± 2, b* = 0 ± 4; the average reflectivity at an incident angle of 30° is <0.6%, and the average reflectivity at an incident angle of 60° is <2.6%; the wide-band wide-angle antireflection film prepared in this example realizes near "zero" reflection and low color deviation display effects in the visible light and near-infrared bands within the range of 0 - 60°. The wear resistance test refers to the test standard GB / T 1768 - 2006, and a friction resistance tester (general equipment) is selected. The wide-band wide-angle antireflection film is subjected to cyclic friction detection with non-woven fabric (2 cm * 2 cm) under a loading force of 500 g. After 1000 times of friction, there is no optical discoloration on the surface of the film material, and the number of scratches is <5, indicating its excellent wear resistance. The bending test shows no cracks after 200K cycles.

[0085] Comparative Example 1

[0086] The difference between this example and Example 1 is only that: this example does not include the first refractive index material layer, the second refractive index material layer, and the protective layer. The preparation method of the antireflection film in this example includes the following steps:

[0087] S1. First, the transparent substrate is subjected to plasma treatment, which is the same as that in Example 1;

[0088] S2. A residual layer and a micro-nano structure layer are formed on the plasma-treated transparent substrate by a roll-to-roll nanoimprinting process:

[0089] An ultraviolet curable resin (ultraviolet curable resin of model MM1078 from Morphotonics company) is coated on the second refractive index material layer to form an imprint ultraviolet curable resin layer. An imprint template containing a quadrangular pyramid micro-nano structure array pattern is pressed into the imprint ultraviolet curable resin layer; after ultraviolet curing and shaping, the mold is removed, and the quadrangular pyramid micro-nano structure array pattern on the imprint template is transferred to the imprint ultraviolet curable resin layer to form a micro-nano structure layer, and the imprint ultraviolet curable resin layer between the micro-nano structure layer and the second refractive index material layer forms a residual layer. The process parameters of the imprinting process are: the imprinting pressure is 6.5 bar, the wavelength of the ultraviolet curing light source is 380 nm, and the curing energy is 6 J / cm 2, the imprinting speed is 1 m / min; an antireflection film is obtained.

[0090] Figure 5 FIG. 4 is a reflection spectrum diagram of the antireflection film of Comparative Example 1 at different incident angles. In the wavelength range of 380 - 1100 nm, the average reflectance at incident angles of 8°, 30°, and 60° is < 1.2%, < 1.4%, and < 3.8%, respectively. For the abrasion resistance test, referring to the test standard GB / T 1768 - 2006, a friction resistance testing machine (general equipment) is selected. The wide-band wide-angle antireflection film is subjected to cyclic friction detection with a non-woven fabric (2 cm * 2 cm) under a loading force of 500 g. After 1000 times of friction, there are > 5 scratches on the surface of the film material and the structure is damaged. For the bending test, there are no cracks after 200 K cycles. It can be seen that compared with Example 1, by removing the first refractive index material layer, the second refractive index material layer, and the protective layer in the graded refractive index structure layer, the wide-band wide-angle antireflection film formed by only imprinting the residual layer and the micro-nano structure layer on the transparent substrate through the nanoimprinting process has an increased reflectance at different incident angles and a decreased environmental damage resistance performance.

[0091] Although the embodiments of the present invention have been disclosed as above, they are not limited to only the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. An ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect, characterized in that It includes a transparent substrate, a gradient refractive index structure layer, a micro-nano structure layer, and a protective layer that are stacked in sequence. The gradient refractive index structure layer includes a first refractive index material layer, a second refractive index material layer, and a residual layer that are stacked in sequence from the side of the transparent substrate.

2. The ultra-wide-angle antireflection film based on thin-film interference and subwavelength effect according to claim 1, characterized in that, The refractive indices of the material of the first refractive index material layer, the material of the second refractive index material layer, and the material of the residual layer at 550 nm are denoted as n1, n2, and n3 respectively, and satisfy: 1.45 ≤ n1 ≤ 1.8, 1.38 ≤ n2 ≤ 1.55, 1.3 ≤ n3 ≤ 1.

5.

3. The ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect according to claim 2, characterized in that, The material of the first refractive index material layer is AL2O3, or a mixture of AL2O3 and SiO2, and the mass ratio of SiO2 is not more than 50%; the thickness of the first refractive index material layer is 60 - 100 nm.

4. The ultra-wide-angle antireflection film based on thin-film interference and subwavelength effect according to claim 2, wherein The material of the second refractive index film layer is one of SiO2, a mixture of AL2O3 and SiO2 (SiO2 accounts for ≥ 50%), and MgF2. When the material of the second refractive index film layer is a mixture of AL2O3 and SiO2, the mass ratio of SiO2 is not less than 50%; the thickness of the second refractive index film layer is 30 - 70 nm.

5. The ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect according to claim 2, characterized in that, The residual layer is an ultraviolet curable resin with a thickness of 50 - 90 nm.

6. The ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect according to claim 1, wherein The micro-nano structure layer is composed of a quadrangular frustum micro-nano structure array. The material of the micro-nano structure layer is an ultraviolet curable resin, and the refractive index n4 at 550 nm satisfies: 1.3 ≤ n4 ≤ 1.

5.

7. The ultra-wide-angle antireflection film based on thin-film interference and subwavelength effect according to claim 6, characterized in that, The height of the quadrangular frustum micro-nano structure is H, the long side width of the bottom end is D, the long side width of the top end is d, and the period repetition of the quadrangular frustum micro-nano structure is P, and satisfies: H:D = 1.5:1, H = 120 nm - 240 nm, D = 80 nm - 180 nm, d = 10 nm - 80 nm, P = 160 nm - 240 nm.

8. The ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect according to claim 1, wherein The material of the protective layer is one of silicon dioxide, silicon nitride compound, and aluminum oxide, and the thickness is 1 - 20 nm.

9. A method for preparing an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect according to any one of claims 1-8, characterized in that, It includes the following steps: S1. Perform plasma treatment on the transparent substrate; S2. Prepare the first refractive index material layer on the plasma-treated transparent substrate by a roll-to-roll magnetron sputtering process; S3. Prepare the second refractive index film layer on the first refractive index material layer by a roll-to-roll magnetron sputtering process; S4. Form the residual layer and the micro-nano structure layer on the second refractive index film layer by a roll-to-roll nanoimprinting process; S5. Prepare the protective layer on the surface of the micro-nano structure layer by a magnetron sputtering, electron beam evaporation, or atomic layer deposition process, and finally obtain an ultra-wide-angle antireflection film based on thin film interference and sub-wavelength effect.

10. The preparation method of the ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effect according to claim 9, characterized in that, It includes the following steps: S1. First, perform plasma treatment on the transparent substrate. The power of the plasma treatment is 200 - 500 W. Use a mixed gas of Ar and O2 as the gas source. The Ar flow rate is 30 - 80 sccm, the O2 flow rate is 350 - 450 sccm, and the linear velocity is 0.3 - 1 m / min. S2. Prepare the first refractive index material layer on the plasma-treated transparent substrate by using a roll-to-roll magnetron sputtering process. Use a mixed gas of Ar and O2 for reactive sputtering, with a rotational target power of 9000 - 13000 W, an Ar flow rate of 50 - 100 sccm, an O2 flow rate of 50 - 100 sccm, and a linear velocity of 0.3 - 1 m / min; S3. Prepare the second refractive index film layer on the first refractive index material layer by using a roll-to-roll magnetron sputtering process. Use a mixed gas of Ar and O2 for reactive sputtering, with a rotational target power of 8000 - 1000 W, an Ar flow rate of 50 - 100 sccm, an O2 flow rate of 50 - 100 sccm, and a linear velocity of 0.3 - 1 m / min; S4. Form a residual layer and a micro-nano structure layer on the second refractive index film layer through a roll-to-roll nanoimprinting process: Coat an ultraviolet (UV) curable resin on the second refractive index material layer to form an imprinted UV curable resin layer, and press an imprinting template containing a quadrangular frustum micro-nano structure array pattern into the imprinted UV curable resin layer; after UV curing and shaping, demold, and transfer the quadrangular frustum micro-nano structure array pattern on the imprinting template to the imprinted UV curable resin layer to form a micro-nano structure layer, and the imprinted UV curable resin layer between the micro-nano structure layer and the second refractive index material layer forms a residual layer. The process parameters of the imprinting process are: the imprinting pressure is 3-10 bar, the wavelength of the UV curing light source is 315-450 nm, and the curing energy is 4-8 J / cm 2 , and the imprinting speed is 0.5-1.5 m / min; S5. Prepare a protective layer on the surface of the micro-nano structure layer by using a roll-to-roll magnetron sputtering process. Use a mixed gas of Ar and O2 for reactive sputtering, with a coating power of 8000 - 10000 W, an Ar flow rate of 50 - 100 sccm, an O2 flow rate of 50 - 100 sccm, and a linear velocity of 1 - 3 m / min; Finally, obtain an ultra-wide-angle antireflection film based on thin-film interference and sub-wavelength effects.

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