An antireflection film, a preparation method thereof, and an application thereof

Abstract

The present invention discloses an antireflection film, a preparation method thereof and an application thereof. The method comprises the following steps: S1, mixing a dispersion liquid containing inorganic oxide, a photocurable adhesive and a solvent to obtain a mixed liquid; S2, coating the mixed liquid on at least one side of a transparent substrate and performing a curing treatment to obtain a hardened film; S3, placing the hardened film on a metal substrate and performing oxygen plasma etching to obtain an antireflection film. The preparation method of the antireflection film provided by the present invention has a simple process, causes no pollution to the environment during the preparation process, and can effectively improve the light transmittance.

Description

Technical Field

[0001] The present invention relates to the technical field of optical thin films, and particularly relates to an antireflection film, a preparation method thereof, and an application thereof. Background Art

[0002] An antireflection film (AR), also called an AR film, is generally formed by stacking 1 - 4 layers of thin films on a substrate, and it uses the principle of destructive interference of multiple optical films to reduce the visible light reflectivity and thereby increase the light transmittance. Preparing an antireflection film on the surface of display glass or showcase glass is beneficial to reducing ambient light reflection and improving display clarity.

[0003] The methods for preparing antireflection films can be divided into two methods: vacuum magnetron sputtering and wet coating. Among them, wet coating has the advantages of low cost and continuous large - area production. According to the number of film layers, it can be divided into single - layer antireflection films and multi - layer antireflection films.

[0004] The design of a single - layer antireflection film layer is to design and control the refractive index and thickness of the film layer according to the conditions of optical destructive interference. Assuming the refractive index of air is n air is 1, and the refractive index of the substrate n 0 ≈1.5 (refractive index of glass), then the refractive index n of the single - layer film should be between 1 and 1.5, and the refractive index thickness is d = λ / 4n, where λ is the incident light wavelength. It is very difficult to obtain a low - refractive - index material with a refractive index of about 1.2 in wet coating.

[0005] Since the refractive index of air is 1.0, introducing pores into the material can effectively reduce its refractive index. One method is hollow silica nanoparticles, that is, a core - shell structure nanoparticle with a polymer inner layer and a silica outer layer is first prepared by the sol - gel method, and then the internal organic matter is removed by high - temperature calcination and other methods to obtain hollow silica nanoparticles. The film prepared by coating this material has a lower refractive index, can significantly reduce the light reflection on the substrate surface, and improve the visible light transmittance. The AR film prepared in this way is widely used in photovoltaic glass. However, a high - temperature calcination process of not less than 400 degrees is not applicable to the preparation of flexible film materials, and even removing the internal organic matter before coating is very challenging for the material preparation process.

[0006] Another way is porous silica material. Silica sol with a three - dimensional network structure prepared by the sol - gel method is coated on a substrate to prepare SiO 2A thin film is then heat-treated at a certain temperature to cure it into a thin film with a molecular or even nanoscale structure. Its porous morphology is the result of the aggregation of colloidal particles and thermal strain that make up the silica thin film. The heat treatment temperature is relatively low, about 180 degrees or so. However, it is still higher than the temperature that some flexible substrates can withstand.

[0007] In the related art, oxygen plasma is used to etch micro-nano structures on a PMMA substrate to increase the visible light transmittance to a maximum of about 92% or so. Oxygen is more environmentally friendly than CF 4 but its etching ability is relatively weak. The anti-reflection effect of the sample still needs to be improved by coating a layer of anti-reflection coating CaF on the surface to increase it to more than 94%.

[0008] Therefore, there is an urgent need to develop a preparation method with high light transmittance, which can be prepared on a large scale and is environmentally friendly. Summary of the Invention

[0009] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, a first aspect of the present invention proposes a method for preparing an anti-reflection film, which is environmentally friendly and can effectively improve the light transmittance.

[0010] A second aspect of the present invention also provides an anti-reflection film.

[0011] A third aspect of the present invention also provides an application of the anti-reflection film.

[0012] According to the method for preparing an anti-reflection film according to the first aspect embodiment of the present invention, the following steps are included:

[0013] S1. Mix a dispersion liquid containing inorganic oxides, a photocurable resin, and a solvent to obtain a mixed liquid;

[0014] S2. Coat the mixed liquid on at least one side of a transparent substrate and perform a curing treatment to obtain a hardened film;

[0015] S3. Place the hardened film on a substrate and perform oxygen plasma etching to obtain an anti-reflection film.

[0016] According to the preparation method of the embodiment of the present invention, it has at least the following beneficial effects:

[0017] The method for preparing an anti-reflection film provided by the present invention has a simple process, is environmentally friendly during the preparation process, and can effectively improve the light transmittance. When performing oxygen plasma etching, the presence of a metal substrate enhances the oxygen plasma etching effect and can further improve the light transmittance.

[0018] According to some embodiments of the present invention, the transparent substrate refers to having an average transmittance greater than 90% in the range of 380 - 780 nm.

[0019] According to some embodiments of the present invention, the metal substrate is selected from at least one of iron, copper, aluminum, or stainless steel.

[0020] According to some embodiments of the present invention, the gas pressure of the oxygen plasma is 0.3 to 0.4 mbar.

[0021] According to some embodiments of the present invention, the dispersion liquid containing inorganic oxide is a silica dispersion liquid, and the solid content is 2.5 to 25 mg / mL.

[0022] According to some embodiments of the present invention, the average particle size of the silica is 0.015 to 15 μm.

[0023] According to some embodiments of the present invention, the average particle size of the silica is 15 to 200 nm. Thus, the light transmittance effect is better.

[0024] According to some embodiments of the present invention, the time of the oxygen plasma etching is 10 to 20 min.

[0025] According to some embodiments of the present invention, the power of the oxygen plasma etching is 100 to 200 W. Thus, the etching speed is fast, and the morphology is rough first and then smooth.

[0026] According to some embodiments of the present invention, the purity of oxygen in the oxygen plasma is 99.99%.

[0027] According to some embodiments of the present invention, the flow rate of oxygen is 0.5 to 1 NI / h (0.5 to 1 standard liter per hour, 20 °C, under one standard atmosphere).

[0028] According to some embodiments of the present invention, the volume ratio of the dispersion liquid, the photocurable adhesive, and the solvent is 50 to 400:100 to 350:500 to 1400.

[0029] According to some embodiments of the present invention, the coating method includes at least one of roll coating, blade coating, spraying, dipping, spraying, printing, or atomization.

[0030] According to some embodiments of the present invention, the photocurable adhesive includes a UV resin, a photoinitiator, ethyl acetate, and methyl isobutyl ketone.

[0031] According to some embodiments of the present invention, the UV resin includes an epoxy resin and / or a polyurethane resin.

[0032] According to some embodiments of the present invention, the solvent includes at least one of ethanol, ethyl acetate, or cyclohexanone.

[0033] According to some embodiments of the present invention, the transparent substrate is a flexible substrate or a glass substrate.

[0034] According to some embodiments of the present invention, the transparent substrate includes a cleaning step. Its function is to remove surface dirt and improve the spreadability of the coating solution on the substrate surface.

[0035] According to some embodiments of the present invention, the flexible substrate is selected from polyester films.

[0036] According to some embodiments of the present invention, the polyester film includes at least one of polyethylene terephthalate (PET) film, polycarbonate PC, transparent polyimide CPI, and polymethyl methacrylate PMMA.

[0037] According to some embodiments of the present invention, the glass substrate is selected from at least one of borosilicate glass, quartz glass, or soda-lime glass.

[0038] According to some embodiments of the present invention, the step of curing treatment is: irradiating the transparent substrate coated with the mixture in an ultraviolet lamp box.

[0039] According to the second aspect of the present invention, there is provided an antireflection film prepared by the above-described method.

[0040] The third aspect of the present invention provides an application of the above-described antireflection film or an antireflection film prepared by the above-described method in an in-vehicle display panel and a laptop computer.

[0041] Other features and advantages of the present invention will be described in the following specification, and in part, will become apparent from the specification, or will be understood by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0043] Figure 1 is a schematic flow chart of the method for preparing the antireflection film in Example 1;

[0044] Figure 2 is a schematic diagram of the hardened films prepared in Example 1 and Comparative Example 1 in the plasma chamber;

[0045] Figure 3 is a light transmittance diagram of the antireflection films of Example 1, Comparative Example 1, and Comparative Example 2;

[0046] Figure 4 is a SEM diagram of the antireflection films of Example 1 and Comparative Example 2;

[0047] Figure 5 is an elemental content diagram of the surfaces of the antireflection films of Example 1 and Comparative Example 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in combination with the embodiments. However, the present invention is not limited to these embodiments.

[0049] The reagents, methods, and equipment used in the present invention are all conventional reagents, methods, and equipment in the technical field, unless otherwise specified.

[0050] Example 1

[0051] Example 1 provides a method for preparing an antireflection film, Figure 1 which is a schematic flow chart of the preparation method of Example 1 and includes the following steps:

[0052] Dispersion of inorganic oxide: SiO dispersion with a solid content of 15 mg / mL 2 The dispersion (SiO 2 has an average particle size of 25 nanometers and the solvent is isopropyl alcohol).

[0053] Photocurable adhesive: 8.3 g of UV resin, 0.38 g of photoinitiator, 6 mL of ethyl acetate, and 4 mL of methyl isobutyl ketone.

[0054] Solvent: Ethyl acetate: Methyl isobutyl ketone = 4:6 (volume ratio).

[0055] S1. Mix the dispersion containing inorganic oxide, the photocurable adhesive, and the solvent in a volume ratio of 50:700:500 to obtain a mixed solution;

[0056] S2. Remove the release films on both sides of an 180-micron-thick polyethylene terephthalate (PET) film, and coat the mixed solution on the PET film by electrospray; let it stand for 5 minutes to level naturally; dry it under vacuum for 30 min to volatilize the solvent; and place it in an ultraviolet lamp box and irradiate it for 5 minutes to obtain a hardened film;

[0057] S3. Place the hardened film on a metal substrate made of aluminum. As Figure 2 shown, set the air pressure at 0.3 - 0.4 mbar and perform oxygen plasma etching for 15 min (the power is 140 W and the oxygen flow rate is 0.5 NI / h (normal liter / hour, 20 °C, one standard atmospheric pressure). Among them, the middle part of the metal substrate made of aluminum is a hollowed-out area, the corresponding sample area is area A, and the part in contact with the metal substrate made of aluminum is area B.

[0058] Comparative Example 1

[0059] Comparative Example 1 provides a method for preparing an antireflection film, including the following steps:

[0060] Dispersion of inorganic oxide: SiO dispersion with a solid content of 2.5 - 25 mg / mL 2Dispersion liquid, (SiO 2 with an average particle size of 0.015 to 15 microns).

[0061] Photocurable adhesive: 8.3 g of UV resin, 0.38 g of photoinitiator, 6 mL of ethyl acetate, and 4 mL of methyl isobutyl ketone.

[0062] S1. Mix the dispersion liquid containing inorganic oxides, the photocurable adhesive, and the solvent in a volume ratio of 50:700:500 to obtain a mixed liquid;

[0063] S2. Remove the release films on both sides of a 180-micron-thick polyethylene terephthalate (PET) film, and coat the mixed liquid on the PET film by electrospray; let it stand for 5 minutes to level naturally; evacuate and dry for 10 min - 30 min to volatilize the solvent; and place it in an ultraviolet lamp box and irradiate for 5 minutes to obtain a hardened film;

[0064] S3. Place the hardened film on a glass substrate, as Figure 2 shown, set the air pressure at 0.3 to 0.4 mbar, and perform oxygen plasma etching for 15 min. Among them, there is no hollow area on the glass substrate.

[0065] Comparative Example 2

[0066] Comparative Example 2 provides a method for preparing an antireflection film, and its preparation method and the amount of raw materials used are basically the same as those in Example 1, the difference being that step S3 is missing.

[0067] Performance test

[0068] Perform a light transmittance test on the antireflection films prepared in Example 1 and Comparative Examples 1 - 2.

[0069] Light transmittance: Test the transmittance according to GB / T 2410 in the national standard, and the results are shown in Figure 3 and Table 1.

[0070] Figure 3 is the visible light transmittance diagram of Example 1, Comparative Example 1, and Comparative Example 2, and the specific values are shown in Table 1.

[0071] Table 1 Data of Example 1 and Comparative Examples 1 - 2

[0072]

[0073] Furthermore, perform SEM on the antireflection films prepared in Comparative Example 1 and Comparative Example 2, and the results are shown in Figure 4When plasma is applied to the surface of the substrate during vacuum plasma treatment, ion bombardment will roughen the surface and produce micro-nano structures that can achieve anti-reflection effects. This is also confirmed by SEM scanning electron microscopy. By scanning the upper and lower surface morphologies and elements of the samples of Example 1 and Comparative Example 2 by SEM, it is found that:

[0074] With no O 2 Compared with the plasma treated samples in Comparative Example 2, the upper and lower surfaces of the B area in Example 1 are coarsened, and micro-nano structures appear, and the etching degree of the lower surface is higher than that of the upper surface; Figure 5 It can be seen from the element content analysis chart (the element content is obtained by EDX testing): Compared with the sample of Comparative Example 2 without Plasma treatment, the proportion of oxygen atoms on the treated upper surface increases, the number of carbon atoms decreases, and the number of silicon atoms remains unchanged: This indicates that the oxygen treated by oxygen plasma on the upper surface reacts with organic matter such as carbon on the sample surface, and the first thing to be reduced is the organic components on the surface of the hardened film. At this time, the silicon dioxide in the hardened film is not etched away, and the abundant and pollution-free silicon dioxide particles act as a mask on the surface. Plasma etching occurs in the organic area around the silicon dioxide, forming a coarsened micro-nano structure. The silicon atom ratio of the treated lower surface is zero, and the oxygen content drops sharply. At this time, the silicon dioxide on the lower surface is completely etched away when the organic components are further reduced. Obviously, the etching degree of the lower surface is more severe than that of the upper surface.

[0075] In Example 1, the upper and lower surface environments of area B are different. The interference colors displayed by the lower surface of area B from the metal substrate area and area A have obvious color differences, and the visible light transmittance of area B is as high as 94.6%, while that of area A is only 93.7%. The color difference between the two areas can also be confirmed from the spectrum. This shows that the presence of the metal substrate enhances the plasma etching effect. In the area covered by the general mask, no etching occurs, but the enhanced etching rate of the metal substrate here plays the role of a reverse mask.

[0076] In Comparative Example 1, the transmittance of the sample on the entire glass substrate is only 92.4%, indicating that 2 Plasma etching occurred, but the blocking of the glass did not enhance the plasma etching of the metal substrate. Compared with the sample in area A with no shielding on both sides, the plasma etching effect was weakened.

[0077] In Comparative Example 2, the visible light transmittance of the sample without plasma etching treatment is only 91.6%.

[0078] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for preparing an antireflection film, characterized in that, it comprises the following steps: S1. Mix a dispersion containing inorganic oxide, a photocurable resin, and a solvent to obtain a mixed solution; S2. Coating the mixed solution on at least one side of a transparent substrate, and performing a curing treatment to obtain a hardened film; S3. Placing the hardened film on a metal substrate, and performing oxygen plasma etching to obtain an antireflection film; The dispersion containing inorganic oxide is a silica dispersion, and the solid content is 2.5 - 25 mg / mL.

2. The method for preparing an antireflection film according to claim 1, characterized in that, the average particle size of the silica is 0.015 - 15 μm.

3. The method for preparing an antireflection film according to claim 1, characterized in that, the volume ratio of the dispersion, the photocurable resin, and the solvent is 50 - 400:100 - 350:500 - 1400.

4. The method for preparing an antireflection film according to claim 1, characterized in that, the transparent substrate is a flexible substrate or a glass substrate.

5. The method for preparing an antireflection film according to claim 4, characterized in that, the flexible substrate is selected from polyester films.

6. The method for preparing an antireflection film according to claim 4, characterized in that, the glass substrate is selected from at least one of borosilicate glass, quartz glass, or soda-lime glass.

7. The method for preparing an antireflection film according to claim 1, characterized in that, the power of the oxygen plasma etching is 100 - 200 W.

8. An antireflection film, characterized in that, it is prepared by the method according to any one of claims 1 - 7.

9. The application of the antireflection film according to claim 8, or the antireflection film prepared by the method according to any one of claims 1 - 7 in an in-vehicle display panel and a laptop computer.

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